Suppressing Phase Segregation in Triple Junction Perovskite Solar Cells

A pin-type tandem photovoltaic structure with improved stability under illumination, comprising a perovskite-based upper photovoltaic cell and a lower photovoltaic cell. The upper cell includes a buffer layer made of aluminum oxide with a thickness of 1-5 nm, deposited at a temperature of 25-150°C. The lower cell can be made from silicon, perovskite, or Cu(In,Ga)(S,Se)2. The buffer layer is produced by atomic layer deposition (ALD) at a temperature of 25-150°C.

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Multiple cation-doped perovskite compound for solar cells with improved stability and efficiency compared to conventional perovskite. The compound has a unique composition formula that allows avoiding segregation and phase separation when illuminated. It contains multiple cations like cesium (Cs), formamidinium (FA), and lead halide (PbX3) with a specific ratio. The Cs and FA doping balances the lattice strain and prevents segregation. The absence of methylammonium (MA) improves thermal stability. This compound provides a stable and efficient perovskite solar cell material.

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A method for preparing high-quality perovskite layers for solar cells, comprising incorporating a third component with a molecular size greater than a threshold value into the perovskite crystal structure. The third component, which can be an organic molecule or a substituted alkyl group, is located on the surface and/or grain boundary of the perovskite crystal and enhances passivation of defects and interfaces. The perovskite layer is then formed through a solution-based method, followed by annealing to remove solvent and crystallize the perovskite structure.

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Perovskite solar cells with high power conversion efficiency and long-term stability to ambient humidity and heat. The cells feature a 3D/2D perovskite heterojunction where the 2D perovskite layer is anchored to the 3D perovskite layer with oleylammonium-iodide molecules. This heterojunction is formed at the electron-selective interface, enabling efficient top-contact passivation and suppressing ion migration. The cells demonstrate a power conversion efficiency of 24.3% and retain >95% of their initial value after >1000 hours of damp-heat testing, meeting industry stability standards for photovoltaic modules.

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A solar cell with an energy-selective contact layer that enables hot carrier transport through a single material, eliminating the need for quantum dots or complex deposition processes. The energy-selective contact layer is formed from a low-dimensional perovskite material that selectively transports electrons or holes, enabling efficient hot carrier extraction and conversion.

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The rapid success achieved from perovskite solar cell has drawn great expectations for commercialization of next-generation photovoltaics. Among the various perovskite materials, the inorganic perovskite derivatives have been of particular interest, ascribed to its superior thermal and chemical stability, which is a crucial criterion for reliable long-term operation. Nonetheless, the development of the efficient inorganic perovskite solar cells has been lagged from its organicinorganic hybrid counterparts owing to the notorious phase-stability challenges associated with the formation of non-photoactive phases. The early progress of the inorganic perovskite solar cells has been centered on the stable perovskite phase-preparation and leads to the effective bulk management through intermediate engineering and compositional engineering strategies. Yet, challenges remain in securing the as-formed perovskite phase throughout the long-term operation. Accordingly, recent studies find interfacial modification strategies successful by constricting the phase-transformation channels in various ... Read More

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A method for preparing a solar cell with improved efficiency and stability, comprising forming a perovskite absorption layer with monocrystal perovskite particles arranged in a bonding matrix, where at least some particles have convex surfaces protruding from both sides of the matrix. The method further includes forming functional layers on the particle surfaces and carrier transport layers on the absorption layer surfaces to enhance carrier transport and reduce recombination.

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A perovskite solar cell with improved efficiency and stability, comprising a perovskite material with reduced crystal defects, achieved through the use of specific ionic compounds containing a five-membered heterocyclic ring as a passivation layer or additive. The compounds, represented by formulas (3) to (5), are designed to suppress and repair defects in the perovskite material, resulting in enhanced photovoltaic performance and stability.

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Perovskite solar cells with optimized grain boundary grooves (GBGs) that enhance opto-electronic properties through controlled void formation. The GBG structure, characterized by a specific side-angle between adjacent grains, is engineered to create a stable heterointerface between the perovskite layer and the substrate. This GBG architecture addresses the conventional issue of GB-induced delamination and void formation, while maintaining carrier injection and transport efficiency. The GBG side-angle range of 5-30 degrees is optimized for perovskite performance while minimizing GB-related degradation.

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All-perovskite tandem solar cells have exhibited greater potential in achieving power conversion efficiencies that are higher than those of single-junction devices. However, commonly used I/Br mixed wide-bandgap (WBG) perovskites, as an important component in the tandem device, always show a photoinduced halide phase segregation, which results in a large open-circuit voltage deficit and low photostability of the final all-perovskite tandem solar cells. In this work, we successfully stabilized the phase of the WBG perovskite by constructing a 2D wrapped 3D structure via introducing larger organic cation 2-(4-fluorophenyl)ethylamine hydroiodide, which has a high activation energy of ion migration to suppress the halide phase segregation. The phase-stable WBG perovskite solar cells achieved a high open-circuit voltage of 1.35 V with a power conversion efficiency of 19.4% and retain 92.1% of their initial value after 500 h of AM1.5G illumination. Finally, the constructed all-perovskite tandem solar cells achieved a high efficiency of 27%.

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The phase segregation of wide-bandgap perovskite is detrimental to a devices performance. We find that Sodium Benzenesulfonate (SBS) can improve the interface passivation of PTAA, thus addressing the poor wettability issue of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine](PTAA). This improvement helps mitigate interface defects caused by poor contact between the perovskite and PTAA, reducing non-radiative recombination. Additionally, enhanced interface contact improves the crystallinity of the perovskite, leading to higher-quality perovskite films. By synergistically controlling the crystallization and trap passivation to reduce the phase segregation, SBS-modified perovskite solar cells (PSCs) achieved a power conversion efficiency (PCE) of 20.27%, with an open-circuit voltage (Voc) of 1.18 V, short-circuit current density (Jsc) of 20.93 mA cm2, and fill factor (FF) of 82.31%.

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With the rapid progress in a power conversion efficiency reaching up to 26.1%, which is among the highest efficiency for single-junction solar cells, organicinorganic hybrid perovskite solar cells have become a research focus in photovoltaic technology all over the world, while the instability of these perovskite solar cells, due to the decomposition of its unstable organic components, has restricted the development of all-inorganic perovskite solar cells. In recent years, Br-mixed halogen all-inorganic perovskites (CsPbI3xBrx) have aroused great interests due to their ability to balance the band gap and phase stability of pure CsPbX3. However, the photoinduced phase segregation in lead mixed halide perovskites is still a big burden on their practical industrial production and commercialization. Here, we demonstrate inhibited photoinduced phase segregation all-inorganic CsPbI1.2Br1.8 films and their corresponding perovskite solar cells by incorporating a 1-butyl-1-methylpiperidinium tetrafluoroborate ([BMP]+[BF4]) compound into the CsPbI1.2Br1.8 films. Then, its effect on the pero... Read More

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Solar battery with improved thermal durability, comprising a perovskite compound photoelectric conversion layer, an intermediate layer containing a heterocyclic compound with a six-membered ring having lone pairs at the 1- and 4-positions, and a second electrode. The heterocyclic compound terminates X-site vacancies in the perovskite compound, forming strong bonds between the lone pairs and B ions that stabilize the perovskite structure and enhance thermal resistance.

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Perovskite solar cells (PSCs) that incorporate both two-dimensional (2D) and three-dimensional (3D) phases possess the potential to combine the high stability of 2D PSCs with the superior efficiency of 3D PSCs. Here, we demonstrated in situ phase reconstruction of 2D/3D perovskites using a 2D perovskite single-crystal-assisted method. A gradient phase distribution of 2D RP perovskites was formed after spin-coating a solution of the 2D RuddlesdenPopper (RP) perovskite single crystal, (DFP)2PbI4, onto the 3D perovskite surface, followed by thermal annealing. The resulting film exhibits much reduced trap density, increased carrier mobility, and superior water resistance. As a result, the optimized 2D/3D PSCs achieved a champion efficiency of 24.87% with a high open-circuit voltage (VOC) of 1.185 V. This performance surpasses the control 3D perovskite device, which achieved an efficiency of 22.43% and a VOC of 1.129 V. Importantly, the unencapsulated device demonstrates significantly enhanced operational stability, preserving over 97% of its original efficiency after continuous light ir... Read More

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Tandem photovoltaic device comprising a silicon-based sub-cell and a perovskite-based sub-cell, where the perovskite sub-cell includes a N-type layer formed from metal oxide nanoparticles with controlled carbon content, achieved through a low-temperature process involving dispersion deposition and carbon elimination treatment. The N-type layer is characterized by a reduced carbon content of less than 20% and a roughness average value of 3-10 nm. The device exhibits improved photovoltaic conversion efficiency compared to conventional tandem devices.

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The recent tremendous progress in monolithic perovskite-based double-junction solar cells is just the start of a new era of ultra-high-efficiency multi-junction photovoltaics. We report on triple-junction perovskiteperovskitesilicon solar cells with...

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Abstract Widebandgap metal halide perovskites have demonstrated promise in multijunction photovoltaic (PV) cells. However, photoinduced phase segregation and the resultant low opencircuit voltage ( V oc ) have greatly limited the PV performance of perovskitebased multijunction devices. Here, a alloying strategy is reported to achieve uniform distribution of triple cations and halides in widebandgap perovskites by doping Rb + and Cl with small ionic radii, which effectively suppresses halide phase segregation while promoting the homogenization of surface potential. Based on this strategy, a V oc of 1.33 V is obtained from singlejunction perovskite solar cells, and a V OC approaching 3.0 V and a power conversion efficiency of 25.0% (obtained from reverse scan direction, certified efficiency: 24.19%) on an 1.04 cm 2 photoactive area can be achieved in a perovskite/perovskite/cSi triplejunction tandem cell, where the certification efficiency is by far the greatest performance of perovskitebased triplejunction tandem solar cells. This work overcomes the performance deadlock of ... Read More

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Wide-bandgap (WB) mixed-halide perovskite solar cells (PSCs) play a crucial role in perovskite-based tandem solar cells (TSCs), enabling them to exceed the Shockley-Queisser limits of single-junction solar cells. Nonetheless, the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs, thus impeding the commercialization of perovskite-based TSCs. Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained. In this review, we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices. The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized. Beyond that, the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed. Finally, the prospects for developing highly efficient and stable WB PSCs in tandem application are also ... Read More

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Abstract Mixedhalide perovskites show promising applications in tandem solar cells owing to their adjustable bandgap. One major obstacle to their commercialization is halide phase segregation, which results in large opencircuit voltage deficiency and J V hysteresis. However, the ambiguous interplay between structural origin and phase segregation often results in aimless and unspecific optimization strategies for the device's performance and stability. An atomic scale is directly figured out the abundant RuddlesdenPopper antiphase boundaries (RPAPBs) within a CsPbIBr 2 polycrystalline film and revealed that phase segregation predominantly occurs at RPAPBenriched interfaces due to the defectmediated lattice strain. By compensating their structural lead halide, such RPAPBs are eliminated, and the decreasing of strain can be observed, resulting in the suppression of halide phase segregation. The present work provides the deciphering to precisely regulate the perovskite atomic structure for achieving photostable mixed halide widebandgap perovskites of highefficiency tandem s... Read More

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Perovskitebased triplejunction solar cells have recently gained significant attention and are rapidly developing, thanks to the insights gained from the advancement in its dualjunction counterparts. However, employing perovskite materials in multijunction solar cells with more than two junctions brings new challenges that have not yet been addressed. One aspect is the possibility of reverse bias breakdown of perovskite subcells during operation of the triplejunction device. This is more relevant for triplejunction solar cells because a higher reverse voltage might drop at perovskite subcells compared to the case of dualjunction solar cells. Herein, the breakdown voltages of the two perovskite subcells in perovskite/perovskite/silicon triplejunction solar cells are determined by progressively increasing the reverse bias applied to the subcells in a singlejunction architecture during currentvoltage measurements and monitoring the appearance of shunts using illuminated lockin thermography measurements. Furthermore, to analyze the effect on the final triplejunction solar cell,... Read More

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As the demand for sustainable energy sources increases, the multi-junction solar cell is an attractive approach to achieve high-energy density, overcoming the efficiency limit of single-junction solar cells. Halide perovskites...

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Abstract Integrating perovskite solar cells with crystalline silicon bottom cells in a monolithic twoterminal tandem configuration enables power conversion efficiency (PCE) surpassing the theoretical limits of singlejunction cells. However, wide bandgap (WBG) perovskite films face challenges related to phase stability and open circuit voltage ( V OC ) deficit, particularly due to severe nonradiative recombination at the perovskite/C 60 interface. Here, the interfacial defects are passivated by incorporating a reactive passivator that reacts with lead halides to form lowdimensional phases. The target product obtained by optimizing the reaction temperature not only suppresses recombination across the interface, but also facilitates the transfer of charge carriers. More importantly, this product can suppress phase segregation of WBG perovskite films under exposure to light illumination and moisture. This strategy enables a high V OC of 1.25 V for WBG perovskite device based on polymer hole transport layer and a certified stabilized PCE of 30.52% for a monolithic perovskite/silicon t... Read More

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Perovskitebased triplejunction solar cells offer the potential for highly efficient and costeffective photovoltaic energy conversion. This article aims to provide a roadmap for the optical properties of perovskite/perovskite/silicon triplejunction cells. A comprehensive optoelectrical model for the perovskite/perovskite/silicon structure is developed in Sentaurus TCAD. The optical part of the model is validated by measurements of a triplejunction solar cell. As the electrical characterization is an ongoing process, the electrical properties are assumed to be nonlimiting, which enables us to translate the optical improvement steps into efficiency potentials. A first improvement step lies in adjusting the thicknesses of the perovskite layers to achieve current matching between both perovskite subcells. Using perovskites with bandgaps optimized for planar surfaces, it would be possible to increase the photocurrent density to 13.3 mA cm 2 and the efficiency to 41.9%. It is shown that by implementing a fully textured structure and using the best available materials, a shortcircuit ... Read More

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Abstract Widebandgap (WBG) perovskite solar cells (PSCs) are recognized as promising candidates for diversified photovoltaics (PVs), such as tandem devices, indoor PVs, and semitransparent buildingintegrated PVs. However, these WBG perovskites made from a mixedhalides strategy suffer from severe phase segregation under continuous illumination, leading to exacerbated nonradiative recombination, and consequently decreased opencircuit voltage and efficiency. In this review, the generation and reversal processes of phase segregation in WBG perovskites are meticulously introduced. Additionally, the major characterization techniques for phase segregation are presented. A detailed summary of recent progress in enhancing photostability of WBG PSCs through various strategies is provided. These strategies primarily concentrate on composition regulation, crystallization modulation, inhibition of ion migration, and strain regulation. Finally, perspectives and potential directions are carefully discussed to promote the further development of highefficiency and photostable WBG PSCs.

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Abstract Developing efficient widebandgap perovskites is critical to exploit the benefits of a multiabsorber solar cell and engineering commercially attractive tandem solar cells. Here, a robust, additivefree, methylammoniumfree triple halide composition for the fabrication of closetoideal widebandgap perovskites (1.64 eV) is reported. The introduction of low percentages of chloride into the perovskite layer avoided photoinduced halide segregation and lead to an evident improvement in the crystallization process, reaching enhanced opencircuit voltages as high as 1.23 V. A perovskite of these characteristics is introduced for the first time in a pin singlejunction configuration using a selfassembled monolayer, with devices achieving photoconversion efficiencies of up to 22.6% with ultrahigh stability, retaining 80% of their initial efficiency after >1000 h of continuous operation unencapsulated in a nitrogen atmosphere at 85 C. This result paves the way toward highly efficient multijunction tandem solar cells, bringing perovskite technology closer to commercializati... Read More

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The efficiency of perovskite/silicon tandem solar cells has exceeded the previous record for III-V-based dual-junction solar cells. This shows the high potential of perovskite solar cells in multi-junction applications. Perovskite/perovskite/silicon triple-junction solar cells are now the next step to achieve efficient and low-cost multi-junction solar cells with an efficiency potential even higher than that for dual-junction solar cells. Here we present a perovskite/perovskite/silicon triple-junction solar cell with an open circuit voltage of >2.8 V, which is the record value reported for this structure so far. This is achieved through employing a gas quenching method for deposition of the top perovskite layer as well as optimization of interlayers between perovskite subcells. Moreover, for the measurement of our triple-junction solar cells, precise measurement procedures are implemented to ensure the reliability and accuracy of the reported values.

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Reducing the structural, chemical, and/or electronic properties of a surface layer. The reduction includes a method for creating an improved quality 2D materials, including a perovskite, a second layer, and a perovskite-like material.

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The 2D/3D perovskite heterostructures have been widely investigated to enhance the efficiency and stability of perovskite solar cells (PSCs). However, rational manipulation of phase distribution and energy level alignment in such 2D/3D perovskite hybrids are still of great challenge. Herein, we successfully achieved spontaneous phase alignment of 2D/3D perovskite heterostructures by concurrently introducing both 2D perovskite component and organic halide additive. The graded phase distribution of 2D perovskites with different n values and 3D perovskites induced favorable energy band alignment across the perovskite film and boosted the charge transfer at the relevant heterointerfaces. Moreover, the 2D perovskite component also acted as a "band-aid" to simultaneously passivate the defects and release the residual tensile stress of perovskite films. Encouragingly, the blade-coated PSCs based on only 2 s in-situ fast annealed 2D/3D perovskite films with favorable energy funnels and toughened heterointerfaces achieved promising efficiencies of 22.5 %, accompanied by extended lifespan. To... Read More

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A perovskite photoelectric device with improved durability, comprising a hole transport layer, a perovskite layer, and a graded wall formed between the two layers. The graded wall suppresses anion movement from the perovskite layer, preventing degradation and extending the device's lifespan. The graded wall can be formed by spray coating a second perovskite compound onto the hole transport layer, with a thickness of 0.5 nm to 100 μm. The device can be fabricated using a method that includes forming the graded wall, followed by deposition of the perovskite layer and electron transport layer.

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Improved stability and efficiency of two-terminal monolithic perovskite-silicon tandem solar cells will require reductions in recombination losses. By combining a triple-halide perovskite (1.68 electron volt bandgap) with a piperazinium iodide interfacial modification, we improved the band alignment, reduced nonradiative recombination losses, and enhanced charge extraction at the electron-selective contact. Solar cells showed open-circuit voltages of up to 1.28 volts in p-i-n single junctions and 2.00 volts in perovskite-silicon tandem solar cells. The tandem cells achieve certified power conversion efficiencies of up to 32.5%.

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A method for preparing a perovskite material layer for solar cells that enhances charge transport and efficiency. The method involves adding N-type or P-type nano-conductive particles to the perovskite precursor solution, which are then enriched at grain boundaries during crystallization to form channels. A barrier layer is also applied to prevent charge recombination and passivate surface defects. The resulting perovskite material layer exhibits improved charge extraction and transmission, leading to enhanced solar cell performance.

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A method for improving the performance of Sn-Pb perovskite solar cells by incorporating a quasi-2D perovskite-like phase into the 3D perovskite structure. The quasi-2D phase is formed by combining phenethylammonium iodide (PEAI) and guanidinium thiocyanate (GASCN) in the perovskite precursor solution, which significantly reduces defects and improves the optoelectronic properties of the Sn-Pb perovskite layer. The resulting composition enables the synthesis of narrow-bandgap Sn-Pb perovskite cells with efficiencies up to 22.1% and tandem devices with efficiencies up to 25.5%.

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A method of forming a perovskite solar cell with improved stability and efficiency, comprising forming a hole transport layer comprising an organosulphur additive, such as 1-DDT, which reduces crystalline domain formation, pinhole size, and moisture sensitivity while maintaining optimal energy level alignment and carrier extraction efficiency. The additive enables a one-step oxidation process, eliminating the need for additional chemical doping, and enhances long-term stability under ambient conditions.

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Solar cell with improved efficiency through enhanced carrier transport in tandem structures. The cell features a photovoltaic part with a perovskite compound layer and a separate semiconductor layer with different crystal structure, while maintaining the same semiconductor material. The perovskite layer enables efficient charge transport, and the separate semiconductor layer ensures precise control over the photovoltaic performance. The tandem structure enables carrier movement through the perovskite layer while maintaining passivation characteristics through a thin intermediate film. The cell achieves enhanced efficiency through optimized carrier transport and reduced barrier effects.

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${\mathrm{CsPbI}}_{3}$ is an inorganic perovskite solar cell material with a band gap appropriate for solar cell applications and photo conversion efficiency greater than 18%. However, this material is also known to undergo many phase transformations within the perovskite structure, starting from a high-temperature cubic phase to a tetragonal phase, leading to a room-temperature orthorhombic phase, with each phase having a different photovoltaic response. The tetragonal phase has been shown to have the highest photoconversion efficiency (18.4%), followed by the cubic phase (17%) and the orthorhombic phase (12.5%). In this work, we use the newly formulated first-principles--based effective Hamiltonian for ${\mathrm{CsPbI}}_{3}$ to investigate the phase transformation sequence in ${\mathrm{CsPbI}}_{3}$ thin films. We investigate the effect of film thickness and substrate strain on the phase transformations and the room-temperature phase. The effect of screening is also investigated. The three perovskite phases previously found in bulk by experiments and by computations were also found ... Read More

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Combining the superior photovoltaic performance of three-dimensional perovskites and the intrinsic durability of two-dimensional perovskites, the construction of 3D/2D perovskite bilayer heterojunctions is a promising strategy to realize efficient and stable perovskite solar cells, but it is still a challenge to control the phase purity, film thickness, orientation, and crystal structure of 2D perovskites. Now, a solution-processing strategy has overcome this challenge by directly coating a tailored single-crystal 2D perovskite ink on as-prepared 3D perovskite films, resulting in effective, ultra-stable and phase-pure 3D/2D perovskite bilayer heterojunctions.

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A multifunctional molecule at interface was explored to inhibit phase separation and passivate defects, producing perovskite solar cells with efficiencies of 21.82% (0.05 cm 2 ) and 18.05% (1.92 cm 2 ) at 1.67 eV bandgap with excellent stability.

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Widebandgap perovskites have attracted much attention due to their potential application in perovskitebased tandem solar cells, which can surpass the theoretical efficiency uplimit of singlejunction solar cells. However, photoinduced phase segregation remains one of the most intractable impediments that deteriorate the operational stability of widebandgap perovskites solar cells. Herein, the effect of a series of alkali halides additives on the photoinduced phase segregation of widebandgap perovskites with the composition of FA 0.8 Cs 0.2 Pb(I 0.7 Br 0.3 ) 3 (FA is formamidinium) is systematically studied. By coupling in situ timedependent photoluminescence technique, potassium chloride (KCl) is demonstrated to be the best in suppressing the photoinduced phase segregation. The reduced iodine vacancy defects owing to supplemented chloride ions and the coupling of potassium ions with the accumulated iodide ions at the grain boundaries lead to effective suppression phase segregation. As a consequence, the KClmodified widebandgap perovskite solar cells present a champion efficie... Read More

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A wide-bandgap (WBG) perovskite top component cell is vital for all perovskite-based tandem solar cells. However, such WBG perovskite solar cell (PSC) suffers from inferior crystallinity, huge voltage loss and poor photostability. Herein, we report a amino-acid-type alkylamine, 5-aminolevulinic acid hydrochloride (ALH) additive to address these issues to enhance the performance of WBG PSCs. It is found that the ALH effectively modulates the perovskite crystallization via chemical complexation between the ALH and PbI2, and enhances the crystallinity of the perovskite film. Moreover, the amino acid ALH not only passivates negatively charged deep-level IFA and IPb anti-site defects via NH3+ terminals to reduce voltage loss, but also suppresses photo-induced phase segregation via the coordination between COO groups and halide vacancies. With these merits, the ALH-based PSC delivers an excellent power-conversion efficiency (PCE) of 21.13%, one of the highest values for inverted WBG PSCs. In addition, the air and thermal stability are also significantly improved. Our findings provide a ... Read More

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Phase segregation has been described as a significant factor that limits solar cell efficiency and long-term stability in mixed organicinorganic halide perovskite materials.

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Mixed halide perovskites could be used to fabricate the high-efficient single junction perovskite solar cells (PSCs) and also be assembled into the tandem solar cells. However, those perovskites always suffered from microstrain and phase segregation issues, which tend to bring in extra non-radiative recombinations and aggravate the energy losses and degradation of PSCs. Here, we developed a dual chloride additive strategy to overcome these issues. Compared with the pristine and single additive films, the perovskite films with dual chloride additive possessed the lowest microstrain and the least defects, and thus the activation energy related to phase segregation of those films was improved from 40.21 kJ mol1 to 59.08 kJ mol1. Density functional theory revealed that the iodide ion migration also had been inhibited by the dual chloride additive as the energy barrier increased from 0.41 eV to 0.57 eV. PSCs with dual chloride additive showed a efficiency of 22.94%, higher than that of the pristine PSCs (20.62%) and the single additive PSCs. Moreover, the unencapsulated PSCs with dual c... Read More

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Mixedhalide perovskites with widebandgap (WBG) have been widely applied for tandem solar cells. Nevertheless, WBG perovskite solar cells (PSCs) easily suffer from photoinduced phase segregation, deteriorating their device efficiency and stability. It is a desirable way that the suppression of phase segregation from the strain relaxation in mixedhalide WBG perovskite films. Herein, ptoluene sulfonate (pTS) can effectively release the residual strain in WBG perovskite films by occupying the empty orbitals of the uncoordinated Pb 2+ and halide ion vacancies, as well as improving the crystallinity and passivating the defect states. The outcomes of this strain relaxation are observed to be highly effective in inhibiting phase segregation in WBG perovskite films. Based on the WBG perovskite with pTS, the significantly improved power conversion efficiency (PCE) of 21.12% is accomplished with the lowest opencircuit voltage deficits (410 mV) for the nip PSCs with an optical bandgap of 1.66 eV. And satisfactory stability of PSC has been gained; the encapsulated device maintains effic... Read More

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<h2>Summary</h2> Perovskite/perovskite/silicon triple-junction solar cells hold promise for surpassing their two-junction counterparts in performance. Achieving this requires monolithic integration of a 2.0 eV band-gap perovskite subcell, characterized by a high bromide:iodide ratio (>7:3), and with low-temperature processability and high optoelectronic quality. However, light-induced phase segregation in such perovskites remains a challenge. To address this, we propose modifying the wide-band-gap perovskite with potassium thiocyanate (KSCN) and methylammonium iodide (MAI) co-additives, where SCN increases the perovskite grain size, reducing the grain boundary defect density; K⁺ immobilizes the halide, preventing the formation of halide vacancies; and MA⁺ eliminates the residual light-destabilizing SCN in the perovskite films via double displacement reactions. Our co-additive strategy enables enhanced photostability, whereas individual usage of MAI and KSCN would result in adverse effects. Triple-junction tandem solar cells, incorporatin... Read More

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Tunable bandgap and excellent optoelectronic properties can make perovskite solar cells (PSC) achieve high power conversion efficiencies in single junction as well as tandem architecture. In this work, 3 types of perovskite solar cell architectures i.e., single-junction, all-perovskite tandem and all-perovskite triple-junction, are modeled in SunSolve. The optimized layer thickness, reflection/parasitic absorptions, quantum efficiency, IV characteristics and power conversion efficiencies (PCE) of each cell are analyzed in detail. The single-junction solar cell of CH3NH3PbI3 with bandgap of 1.55 eV produces the PCE of 21.4%. The all-perovskite tandem solar cell of (CH3NH3)0.9Cs0.1Pb(I0.6Br0.4)3 (1.82 eV) as top sub-cell and CH3NH3Pb0.5Sn0.5I3 (1.22 eV) as bottom sub-cell exhibits a PCE of 26.06%. While the all-perovskite triple-junction solar cell of FA0.83Cs0.17Pb(I0.7Br0.3)3 (1.94 eV) as top sub-cell, CH3NH3PbI3 (1.55 eV) as middle sub-cell and CH3NH3Pb0.5Sn0.5I3 (1.22 eV) as bottom sub-cell has the remarkable PCE potential of 28.38%. This work guides towards multi-junction solar ce... Read More

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Wide-bandgap perovskites formed by tuning the iodine/bromine ratio can be combined with narrow-bandgap silicon materials to construct tandem solar cells, thus overcoming the Shockley-Queissel limit. However, light-induced halide ion migration causes poor perovskite film quality and detrimental halide phase segregation in it. Herein, a facile co-doping strategy for wide-bandgap (FA0.65MA0.2Cs0.15)Pb(I08Br0.2)3 film is demonstrated, that is, Pb(SCN)2 and PEACl are synergistically incorporated into perovskite film to break through this hurdle. The proposed strategy not only enables high-quality perovskite films with larger grains, fewer grain boundaries, and high crystallinity, but also the two-dimensional (2D) perovskite formed at grain boundaries effectively suppresses halide phase separation and improves the hydrophobicity of the films. As a result, we achieved a power conversion efficiency (PCE) of 19.92% for the small-area (0.07 cm2) perovskite solar cells (PSCs) and 17.70% for modules with an active area of 10.00 cm2. And, the operational and long-term storage stability of the mo... Read More

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Abstract Widebandgap (WBG) perovskite solar cells have attracted considerable interest for their potential applications in tandem solar cells. However, the predominant obstacles impeding their widespread adoption are substantial opencircuit voltage ( V OC ) deficit and severe photoinduced halide segregation. To tackle these challenges, a crystal orientation regulation strategy by introducing dodecylbenzenesulfonicacid as an additive in perovskite precursors is proposed. This method significantly promotes the desired crystal orientation, passivates defects, and mitigates photoinduced halide phase segregation in perovskite films, leading to substantially reduced nonradiative recombination, minimized V OC deficits, and enhanced operational stability of the devices. The resulting 1.66 eV bandgap methylaminefree perovskite solar cells achieve a remarkable power conversion efficiency (PCE) of 22.40% (certified at 21.97%), with the smallest V OC deficit recorded at 0.39 V. Furthermore, the fabricated semitransparent WBG devices exhibit a competitive PCE of 20.13%. Consequently, four... Read More

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Perovskite Solar Cells In article number 2300020, Congcong Wu, Haijin Li, and co-workers present a contiguous contact of perovskite/carbon interface achieved by in situ formation of 2D perovskite through a solid phase reaction when fabricating a carbon electrode. The 2D perovskite interlayer not only passivates surface defects but also enables a seamless contact at the perovskite/carbon interface and promotes carrier transport, thereby improving power conversion efficiency and stability of hole-transport-layer-free perovskite solar cells simultaneously.

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Abstract Widebandgap (WBG) perovskite solar cells (PSCs) with high performance and stability are in considerable demand to boost tandem solar cell efficiencies. Perovskite bandgap broadening results in a high barrier for enhancing the efficiency of PSCs and phase segregation in perovskite. In this study, it is shown that the residual strain is the key factor affecting the WBG perovskite device efficiency and stability. The dimethyl sulfoxide addition helps lead halide with opening the layer spacing to form intermediate phases that provide more nucleation sites to eliminate lattice mismatch with organic components, which dominates the strain effects on the WBG perovskite growth in a sequential deposition. By minimizing the strain, 1.67 and 1.77 eV nip devices with record efficiencies of 22.28% and 20.45%, respectively, can be achieved. The greatly suppressed phase segregation enables the devices with retained 9095% of initial efficiency over 4000 h of damp stability and 8090% of initial efficiency over 700 h of maximumpowerpoint (MPP) stability. Besides, the 1.67 eV pin devices c... Read More

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Abstract Inorganic metal halide perovskites such as CsPbI 3 are promising for highperformance, reproducible, and robust solar cells. However, inorganic perovskites are sensitive to humidity, which causes the transformation from the black phase to the yellow , nonperovskite phase. Such phase instability has been a significant challenge to longterm operational stability. Here, a surface dimensionality reduction strategy is reported, using 2(4aminophenyl)ethylamine cation to construct a DionJacobson 2D phase that covers the surface of the 3D inorganic perovskite structure. The DionJacobson layer mainly grows at the grain boundaries of the perovskite, effectively passivating surface defects and providing favourable interfacial charge transfer. The resulting inorganic perovskite films exhibit excellent humidity resistance when submerged in an aqueous solution (isopropanol:water = 4:1 v/v) and exposed to a 50% humidity air atmosphere. The DionJacobson 2D/3D inorganic perovskite solar cell (PSC) achieves a power conversion efficiency (PCE) of 19.5% with a V oc of 1.197 eV. It retai... Read More

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The undesired segregation of inactive secondary phase that randomly distributed across the perovskite film is detrimental to charge-carrier transport dynamics and light stability. However, in-depth studies for understanding the underlying chemical reaction mechanism and the relationship between phase structural configuration and physical properties are still lacking. Herein, the segregation behavior of the inactive secondary phase and the underlying microcosmic mechanism regarding ionic chemical replacement reaction and lattice reconfiguration process are systematically elaborated. A high-quality perovskite-PbI2 heterojunction film is constructed via converting the three-dimensional PbI2 photoactive phase into a two-dimensional inactive phase, alleviating the energetic disorder of carrier dynamics and photochemical dissociation. The resultant perovskite solar cells achieve an efficiency of 24.23% with excellent light-resistance. The dissociation energetics of phase dimensional structure is theoretically analyzed. This work provides new insights into crystal structure design for const... Read More

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