Publication date: 21 August 2024
Source: Joule, Volume 8, Issue 8
Author(s): Sheng Fu, Nannan Sun, Yeming Xian, Lei Chen, You Li, Chongwen Li, Abasi Abudulimu, Prabodika N. Kaluarachchi, Zixu Huang, Xiaoming Wang, Kshitiz Dolia, David S. Ginger, Michael J. Heben, Randy J. Ellingson, Bin Chen, Edward H. Sargent, Zhaoning Song, Yanfa Yan
The review article aims to explore future research directions for perovskite solar cells (PSCs), focusing on realizing the full commercial potential. Specifically, large-area fabrication methods and the degradation mechanism of both PSCs and perovskite solar modules (PSMs) are explored in more depth, aiming to achieve high-efficiency and stable devices for commercialization.
Organometal halide perovskite photovoltaic (PV) cells have achieved power conversion efficiencies (PCEs) comparable to the leading crystalline silicon (c-Si) PV technology. However, despite their exceptional performance, these perovskite solar cells (PSCs) face technological challenges such as large-area fabrication complexities and outdoor stability concerns. These challenges need to be addressed to pave the way for the commercialization of PSCs. The key to commercializing PSCs lies in developing stable, large-area solar modules that offer both high efficiency and reliability. Overcoming the hurdles of large-area module design and fabrication is a crucial step, and researchers are exploring innovative solutions to tackle these challenges. This review article primarily focuses on the development of large-area PSCs, recent advancements in this field, and the obstacles related to scaling up this technology. It delves into the techniques used to fabricate perovskite films, with a special emphasis on large-area and large-scale PSC manufacturing methods. Moreover, the review highlights stability concerns that perovskite solar modules (PSMs) face and reports on recent progress in addressing these issues. The article concludes by summarizing potential future research directions aimed at realizing the full commercial potential of this innovative and promising solar cell technology.
The O-capped and NH2-capped MXene quantum dots are prepared to develop efficient O-MQD hole transfer layer (HTL) and E-MQD electron transfer layer (ETL) for organic solar cells. The power conversion efficiencies of the device based on O-MQD HTL and E-MQD ETL are 18.62% and 18.15%, respectively.
The interfacial layers of organic optoelectronic devices generally suffer from the problems of difficulty in regulating the work function (WF) and low mobility, which are prone to mismatch of interfacial energy levels and loss of carrier transport energy. Herein, O-terminated and NH2-terminated Ti3C2T x MXenes quantum dots (MQDs) are synthesized to develop efficient O-MQD hole transfer layer (HTL) and E-MQD electron transfer layer (ETL) for organic optoelectronic devices of organic solar cells (OSCs) and organic photodetectors (OPDs). It is found that the strong electronic coupling interaction between the surface terminations and matrices enables O-MQD and E-MQD with tunable WF and satisfactory conductivity. Consequently, in a binary D18:L8-BO system, the power conversion efficiencies of the OSC device based on O-MQD HTL and E-MQD ETL are 18.62% and 18.15%, respectively. Moreover, the OPDs with O-MQD HTL and E-MQD ETL exhibit higher shot-noise-limited detectivity (D shot*) of 1.24 × 1013 and 1.10 × 1013 Jones, respectively, compared to the devices using classic interlayers. These findings provide some insights into the design of advanced dual-function interlayers for organic optoelectronic devices.
A novel approach using 1D metal-free perovskites, specifically DABCO-NH4Cl3, is proposed to facilitate the crystallization process of 3D FAPbI3 perovskites, while simultaneously addressing surface defects. Benefiting from the better crystallization and defect passivation, the final device reaches an efficiency of 24.72% and maintains more than 90% of its initial efficiency after 120 h of MPPT testing.
The performance of perovskite cells closely relies on the quality of films, leading to a special focus on crystallization manipulation and defect control. In this study, a novel approach using 1D metal-free perovskites, specifically DABCO-NH4Cl3, is proposed to facilitate the crystallization process of 3D FAPbI3 perovskites, while simultaneously addressing surface defects. Analysis of crystallization kinetics reveals that the introduction of 1D metal-free perovskites provides numerous nucleation sites, effectively slowing down crystal growth rates and resulting in the formation of uniform, large-grain perovskite films. Furthermore, the organic groups present in 1D perovskites play a crucial role in passivating defects within the perovskite structure. The synergistic impact of these factors enables the perovskite to achieve an efficiency of 24.72% while demonstrating exceptional stability. This research offers a promising approach for controlling perovskite crystallization, leading to the development of high-efficiency and stable perovskite materials.
The different textures of a polymer and self-assembled monolayer hole transport layers strongly impact the vertical compositional stratification in the perovskite active layer. Specifically, triple cation perovskite layers deposited on the smooth texture of polymers such as PTAA result in a MAPbI3-like composition at the buried interface, leading to enhanced ion migration and thus, poor device stability.
Despite the striking increase in the power conversion efficiency (PCE) of lead-based perovskite solar cells (PSCs), their poor operational stability impedes their commercialization. Among the various factors that influence device stability, ion migration has been identified as a key driver of degradation. In this work, the focus is on studying ion migration-induced degradation in inverted architecture PSCs, which employ either a thin polymer layer or a self-assembled monolayer (SAM) for hole extraction. It is demonstrated that the difference in texture imposed by the use of these hole transport layers (HTL) is an important and thus far inconspicuous factor that impacts ion migration, and consequently device stability. By investigating the buried interface in detail, it is revealed that its texture has a strong impact on the vertical compositional stratification in the perovskite active layer. By monitoring bias-induced ion migration in devices with different hole extraction layers, it is demonstrated that the smooth polymer-based HTL results in a higher degree of ion migration than the rough SAM HTL, corresponding to a stronger degradation in the former. These results further indicate that the use of SAMs for hole extraction is a promising strategy to suppress ion migration and improve device efficiency.
This review summarizes the development of tin-lead perovskites and their applications in single-junction and all-perovskite tandem solar cells. The fundamental structural and optoelectronic properties of tin-lead perovskites and the recent advances with various approaches covering additives, solvents, interfaces, perovskite growth, and charge transport materials are discussed. The challenges and strategies for further development are also provided.
Organic–inorganic metal-halide perovskites have received great attention for photovoltaic (PV) applications owing to their superior optoelectronic properties and the unprecedented performance development. For single-junction PV devices, although lead (Pb)-based perovskite solar cells have achieved 26.1% efficiency, the mixed tin-lead (Sn-Pb) perovskites offer more ideal bandgap tuning capability to enable an even higher performance. The Sn-Pb perovskite (with a bandgap tuned to ≈1.2 eV) is also attractive as the bottom subcell for a tandem configuration to further surpass the Shockley–Queisser radiative limit for the single-junction devices. The performance of the all-perovskite tandem solar cells has gained rapid development and achieved a certified efficiency up to 29.1%. In this article, the properties and recent development of state-of-the-art mixed Sn-Pb perovskites and their application in single-junction and all-perovskite tandem solar cells are reviewed. Recent advances in various approaches covering additives, solvents, interfaces, and perovskite growth are highlighted. The authors also provide the perspective and outlook on the challenges and strategies for further development of mixed Sn-Pb perovskites in both efficiency and stability for PV applications.
A new 2D material MBene is introduced into the buried interface of perovskite solar cells, it can strongly interact with both SnO2 and perovskite layer at the same time, forming a bridge at the buried interface, improving the charge transfer, and regulating the energy level structure, resulting in an enhanced power conversion efficiency of 24.32 % and better stability.
The interface of perovskite solar cells (PSCs) plays an important role in transferring and collecting charges. Interface defects are important factors affecting the efficiency and stability of PSCs. Here, the buried interface between SnO2 and the perovskite layer is bridged by two-dimensional (2D) MBene, which improves charge transfer. MBene can deposit additional electrons on the surface of SnO2, passivate its surface defects and facilitate the charge collection. Moreover, the dipole moment formed at the interface increases the electron transfer ability in the PSCs. MBene also regulates the growth of perovskite crystals, improves the quality of perovskite films, and reduces its grain boundary defects. As a result, PSCs based on FA0.2MA0.8PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 get the enhanced efficiencies of 22.34 % and 24.32 % with negligible hysteresis. Furthermore, the optimized device exhibits better stability. This work opens up the application of MBene materials in PSCs, reveals a deeper understanding of the mechanism behind using 2D materials as an interface modification layer, and shows opportunities for using MBene as potential material in photoelectric devices.
Nature Materials, Published online: 04 June 2024; doi:10.1038/s41563-024-01879-z
Photolysis and ion migration under electrical bias cause intrinsic instability in halide perovskite solar cells. By harnessing materials that both capture and confine iodide and polyiodide ions at the perovskite surface, the stability of devices under ultraviolet irradiation, thermal–light conditions or reverse bias can be greatly increased.
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This work develops a new dimerized acceptor with a bithiophene as a linker. Benefiting from the optimized planarity and decreased energy loss, a synergistical enhancement of V OC and light absorption is achieved. Finally, the corresponding device exhibits a superior efficiency of 18.06% and favorable stability with T85 lifetime of over 1300 h under light soaking.
The highly planar molecular structure is conducive to electron delocalization, thus facilitating efficient charge transport. A new thiophene terminal-linked dimerized small-molecular acceptor (DSMA), DTY-2Cl, is synthesized, which achieves high planarity with a bithiophene linkage. The results of theoretical calculation and single crystal analysis of regional configuration demonstrate that the twisting angle between the bithiophene binding unit of DTY-2Cl is almost zero. Devices based on DTY-2Cl:D18 show an outstanding photoelectric performance with a power conversion efficiency (PCE) of 18.06% and excellent device stability. It is worth noting that DTY-2Cl exhibits a redshifted absorption of up to 840 nm, which is rare among DSMAs, and DTY-2Cl-based devices obtain a V OC of 0.913 V, thus achieving a win-win situation of redshifted absorption and high V OC. These results indicate that using bithiophene instead of biphenyl to optimize the planarity of oligomer acceptors is an effective strategy and provide a new idea for the improvement of subsequent materials.
A novel organic multifunctional additive, 2-(furan-3-yl)ethanamine hydrochloride (FFEACl), is introduced in this study, which plays a pivotal role in promoting the oriented crystallization of the α-phase FAPbI3 and reducing defect density in the resulting perovskite film. Consequently, the top-performing PSC exhibits an impressive power conversion efficiency of 25.41%, along with enhanced operational stability.
Efficient manipulation of crystallization and control over defects are crucial for optimizing the performance and durability of perovskite solar cells (PSCs). In this study, a novel organic multifunctional additive, 2-(furan-3-yl)ethanamine hydrochloride (FFEACl), is introduced which plays a pivotal role in regulating the crystallization process of FAPbI3. Incorporating FFEACl into the perovskite precursor solution effectively suppresses the formation of undesirable non-perovskite phase impurities while promoting the oriented crystallization of the α-phase FAPbI3. Moreover, the addition of FFEACl leads to a more uniform surface potential and reduced defect density in the resulting FAPbI3 film. Consequently, the top-performing PSC exhibits an impressive power conversion efficiency (PCE) of 25.41%, along with enhanced operational stability. Notably, the fabricated PSCs maintain over 80% of their initial PCE even after 1000 h of continuous operation under one-sun illumination. The findings present a facile and effective strategy for fabricating perovskite photovoltaic devices with exceptional performance and long-term reliability.
Benefiting from favorable interaction via coordination and hydrogen bonds, an organic potassium perfluorobutyl sulfonate achieves the target passivation of surface defects of FAPbI3 perovskite films and improved interfacial charge transfer. With such effective defect engineering, champion efficiencies of 25.11%, 24.17%, and 20.18% are demonstrated for small-sized and centimeter-sized solar cells and 5 cm × 5 cm solar mini-modules, as well as good stability.
Passivating surface defects on perovskite films with tailored functional materials has emerged as one of the most effective strategies for achieving high-performance perovskite solar cells (PSCs). Among existing material selections, potassium salts stand out for their effective passivation of defects surrounding perovskite grain boundaries. However, the widely used potassium salts are inorganic and only soluble in highly polar solvents, which limits their practical application for surface passivation. Herein, a novel organic potassium salt (KCFSO), with multiple organic functional groups and good solubility in low polar isopropanol, is reported to function as a post-treatment agent for perovskite. Combined with experimental results and theoretical calculations, the formed multiple intermolecular interactions between KCFSO and perovskite are revealed to play a vital role in determining the defect passivation effect. Thus, the KCFSO-modified film shows a more uniform surface potential distribution, dramatically decreased defect density, and improved charge transfer, leading to a champion power conversion efficiency (PCE) of 25.11%, and good stability for the derived PSCs. As a demonstration of scalability, the centimeter-sized PSCs and 5 cm × 5 cm mini-modules also demonstrate impressive PCEs of 24.17% and 20.18%, respectively. These findings provide insights into passivator design principles to achieve efficient and stable perovskite photovoltaics.
The radical-regulated electron-phonon coupling is studied by embedding two types of r-NG• onto the buried surface of the PVSK layer in inverted PSCs. This strategy significantly accelerates hot-hole injection by augmenting the relaxation channel and promoting the rotation of cation in PVSK. The resultant radical-decorated PSCs delivered an efficiency of 24.20%, along with better thermal and operating stability.
Extracting hot-carriers before they relax back to the band edge will reduce thermal dissipation above the bandgap, which is one of the primary sources of efficiency loss in perovskite solar cells (PSCs). It requires slow cooling of hot-carriers together with the efficient extraction of hot-carriers. Here, a novel interface engineering is demonstrated by embedding radical-containing nanographene (r-NG●) between perovskite and poly[bis(4-phenyl)(2,4-dimethoxyphenyl)-amine] (PTOAA) to harvest this excess energy. This strategy accelerates the extraction rate of the hot-hole (3 times that of control at 400 K) by augmenting the relaxation channel, which is related to the “quasi-SOMO” energy state of r-NG●. Nonadiabatic molecular dynamics calculation further revealed that radical character promotes the rotation of the cation in perovskite, which contributes to generating strong nonadiabatic couplings and multiple phonon modes. In addition, the band bending effect of buried perovskite and improved conductivity of PTOAA also facilitate exciton dissociation and hole collection efficiency (97.5%). Consequently, the resultant r-NG● decorated PSCs delivered an impressive efficiency of 24.20%, along with better thermal and humidity stability. Moreover, it can maintain 93% of its initial efficiency after 300 hours of illumination.
Publication date: September 2024
Source: Nano Energy, Volume 128, Part A
Author(s): Chao Zhou, Fei Wang, Xinbo Ai, Yujun Liu, Yonglei Han, Ling Han, Junsheng Wu, Kang Zhou, Hanlin Hu, Shiyu Wang, Wang-Ting Lu, Zhuo Zhao, Yongfei Wang, Haoran Lin
Al2O3 deposited via atomic layer deposition improves power conversion efficiency, moisture resistance, and long-term stability of formamidinium-cesium perovskite solar cells. 1 nm-thick passivation layer improves fill factor and open-circuit voltage, while 30 nm-thick capping layer acts as an efficient moisture barrier layer. Results from more than 300 devices show significantly improved maximum power point stability, especially under cyclic illumination.
Improving the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) remain the two most important goals of perovskite research. Herein, the effects of Al2O3 interlayer on the performance of formamidinium-cesiums and “triple cation” PSCs by depositing a thin Al2O3 layer via atomic layer deposition on different interfaces are analyzed. It is found that it can efficiently serve as a passivation layer of perovskite absorber, as a seed layer for the compact growth of the subsequent SnO2 layer, or as a capping layer to the whole cell in the superstrate configuration to prevent moisture ingress. The optimized devices utilizing Al2O3 have on average more than 1% absolute higher PCE, with reduced penetration of moisture inside the device. Especially, the capping layer has shown the greatest benefit, extending the stability of the devices by more than two times and allowing long-term operation without encapsulation. In the best case, a T80 time of almost 900 h under day/night-cycling illumination is obtained. The observed trends are based on data from a large number of devices (more than 300 devices were tested in the maximum power point), which give statistical relevance to the promising results.
Publication date: 17 July 2024
Source: Joule, Volume 8, Issue 7
Author(s): Geping Qu, Siyuan Cai, Ying Qiao, Deng Wang, Shaokuan Gong, Danish Khan, Yu Wang, Kui Jiang, Qian Chen, Letian Zhang, Yang-Gang Wang, Xihan Chen, Alex K.-Y Jen, Zong-Xiang Xu
High efficient and stable rigid and flexible n-i-p perovskite solar cells are developed through incorporating 2,5-Furandicarboxylic acid multifunctional intermediate layer between SnO2 layer and perovskite layer to modify the SnO2 surface and passivate the buried interface of perovskite, which achieved high PCE of 24.5% (rigid) and 22.1% (flexible) with excellent ambient and mechanical stability.
Flexible perovskite solar cells (PSCs) have received great attention due to their low weight, high power ratio, and potential applications in wearable electronic products. The efficiency and stability of flexible PSCs are directly affected by the carrier extraction and transport capabilities of electron transport layer. Herein, efficient flexible PSCs are prepared through incorporating 2,5-Furandicarboxylic acid (FDCA) multifunctional intermediate layer between tin oxide (SnO2) and perovskite, which can effectively eliminate defects at the interfacial to increase the electron mobility of the SnO2 layer, modify the surface of SnO2 to shift the conduction band upward to improve interface charge extraction, passivate the buried interface of perovskite to induce larger perovskite crystal growth, and establish a bridge between SnO2 and perovskite to improve charge collection efficiency. As a result, the rigid PSCs with FDCA display a champion power conversion efficiency (PCE) of 24.53% with a high open circuit voltage (V OC) of 1.204 V. Furthermore, the flexible device with FDCA achieves a high PCE of 22.10%, and preserve 90% of its initial PCE after aging for 500 h at ambient condition without encapsulation, and maintain 81% of its original PCE after 10,000 bending cycles.
This work introduces aqueous ammonia (NH3·H2O) to treat SnO2 ETL at 80 °C to reduce the carrier scattering, effectively removing electric double-layer residues of solvated ions tightly bound to the SnO2 grain boundaries. This strategy promotes further oriented attachment growth with better crystallinity, thereby decreasing grain boundaries to reduce carrier scattering. The NR-ETL-based f-PSCs achieved a high PCE of 23.71%, as well as better operational stability and mechanical reliability.
The sol–gel method is efficient and cost-effective for synthesizing SnO2 sol, wherein SnO2 nanocrystallites (NCs) are stabilized by electric double-layer of solvated ions tightly bound to their surface. However, this strong binding makes the removal of electric double-layer residues from the SnO2 electron transport layer (ETL) to be difficult at low temperatures. This hinders both the close contact and subsequent growth among adjacent SnO2 NCs, leading to severe carriers scattering at grain boundary, adversely affecting the electrical properties of SnO2 ETL. Herein, SnO2 sol is synthesized via an ethanol-based sol–gel method and aqueous ammonia (NH3·H2O) is introduced to effectively clean stubborn electric double-layer residues within the SnO2 ETL at a low temperature (80 °C). Removing residues reduces the gap among adjacent SnO2 NCs and promotes further reconstructed growth through oriented attachment (OA), thereby reducing the number of grain boundaries. Hence, the energy barriers for electron transport decrease within the SnO2 ETL. Furthermore, MHP prepared on the treated ETL has fine-tuned energy level alignment, improving the electron extraction capacity. Consequently, flexible perovskite solar cells (f-PSCs) incorporating this ETL achieved a notable increase in power conversion efficiency, rising from 19.16% to 23.71%, as well as superior mechanical stability.
A multi-functional perovskite interface passivation strategy based on guanidinium iodide is proposed. The guanidinium iodide, with its ammonium group, unsaturated nitrogen atoms, and iodide ions, synergistically repairs the perovskite interface defects through various pathways, passivates the grain boundaries, effectively suppresses non-radiative recombination, and significantly improves the photovoltaic performance of the device.
Perovskite solar cells have become a leading contender in next-generation photovoltaic technologies due to their high efficiency and low-cost potential. Managing the deep defects present effectively in the crystal lattice and at the interfaces is essential for enhancing the performance and longevity of perovskite solar cells. Here, perovskite's crystallization modulation and interfacial defect passivation are achieved by developing a guanidinium iodide (GAI)-based surface passivation strategy. The integration of GAI passivates the grain boundaries, leading to a perovskite thin film with a smoother and more uniform grain distribution, facilitating charge carrier transport. Notably, the ammonium group, unsaturated nitrogen atoms, and iodide ions in GAI can collectively repair the surface defects of perovskite through various pathways, effectively suppressing non-radiative recombination, thereby enhancing the photovoltaic performance of the device. Ultimately, the champion device treated with GAI achieves a power conversion efficiency (PCE) of 23.02% and demonstrates similar ambient stability under unencapsulated conditions. These findings underscore the effectiveness of GAI passivation as a strategy to balance the improvement of the performance and stability of perovskite solar cells.
2D n-type SnS is introduced into the PM6:Y6 BHJ organic solar cells. SnS promotes Y6 crystallization and renders the face-on orientation of Y6 molecules dominant. The improved active layer morphology suppresses carrier recombination and boosts electron transport, leading to more balanced hole-electron mobility. With improved V OC, J SC and FF, an optimized PCE of 18.50% is achieved.
The unbalanced electron-hole mobility is the major bottleneck for boosting the photovoltaic performance of organic solar cells. In this study, 2D n-type inorganic semiconductor material tin sulfide (SnS) is prepared and introduced into the PM6:Y6 bulk heterojunction organic solar cells to improve photovoltaic performance. The incorporation of SnS promotes Y6 crystallization, and renders the face-on orientation of Y6 molecules dominant. The improved active layer morphology suppresses carrier recombination and strengthens the electron transport. The electron mobility increases significantly from 4.71 × 10−4 cm2 V−1 s−1 to 7.61 × 10−4 cm2 V−1 s−1 with the hole/electron mobilities (µ h/µ e) value reducing from 1.67 to 1.11. With enhanced and balanced carrier mobility, the open-circuit voltage, short-circuit current density and fill factor of the SnS-doped PM6:Y6 organic solar cells are improved simultaneously, and the power conversion efficiency is boosted from 16.66 to 18.50%. Additionally, the SnS doped devices exhibit better thermal and storage stability. The improved photovoltaic performance is further verified in PM6:L8-BO and D18:Y6 based organic solar cells. This work demonstrates that n-type SnS dopant is an efficient and universal method to improve photovoltaic performance of non-fullerene organic solar cells.
This review summarizes recent advances in buried interface engineering and emphasize the importance of corresponding characterization techniques. The various functions of buried interface engineering are carefully discussed, including crystallization modulation, defect passivation, energy level alignment, chemical reaction inhibition, chemical bridge, dipole cancellation, and novel buried interfacial techniques. Finally, current challenges and prospects are put forwarded that should be addressed to further improve device performance of inverted PSCs.
Interface engineering is known for effectively improving interfacial contact and passivating defects to enhance device performance of inverted perovskite solar cells (PSCs). Currently, most of works focus on surface passivation, while the buried interface is equally important. The film quality of perovskite layer greatly relies on the buried interface, leaving a pronounced impact on overall device performance. In addition, resolving defects and energy level mismatch at buried interface remains challenging. Optimizing the buried interface becomes a promising approach for high-efficiency inverted PSCs. This review summarizes recent advances in buried interface engineering and emphasize the importance of corresponding characterization techniques. The various functions of buried interface engineering are carefully discussed, including crystallization modulation, defect passivation, energy level alignment, chemical reaction inhibition, chemical bridge, dipole cancellation and novel buried interfacial techniques. Finally, current challenges and prospects are put forward that should be addressed to further improve device performance of inverted PSCs.
The molecular encapsulation structure is form colloidal particles and glycerol monostearate in perovskite precursor inks ensuring their consistent response to shear forces. The uniform size of colloidal particles ensures consistent solute deposition during the printing process. The flexible perovskite solar cells achieve a stabilized power conversion efficiency of 24.45% (1.01 cm2) and 15.87% (100 cm2) with minor efficiency discrepancy.
The non-uniform distribution of colloidal particles in perovskite precursor results in an imbalanced response to the shear force during flexible printing process. Herein, it is observed that the continuous disordered migration occurring in perovskite inks significantly contributes to the enlargement of colloidal particles size and diminishes the crystallization activity of the inks. Therefore, a molecular encapsulation architecture by glycerol monostearate to mitigate colloidal particles collisions in the precursor ink, while simultaneously homogenizing the size distribution of perovskite colloids to minimize their diffusion disparities, is devised. The utilization of colloidal particles with a molecular encapsulation structure enables the achievement of uniform deposition during the printing process, thereby effectively balancing the crystallization rate and phase transition in the film and facilitating homogeneous crystallization of perovskite films. The large-area flexible perovskite device (1.01 cm2 and 100 cm2) fabricated through printing processes, achieves an efficiency of 24.45% and 15.87%, respectively, and manifests superior environmental stability, maintaining an initial efficiency of 91% after being stored in atmospheric ambiences for 150 days (unencapsulated). This work demonstrates that the dynamic evolution process of colloidal particles in both the precursor ink and printing process represents a crucial stride toward achieving uniform crystallization of perovskite films.
Nature Energy, Published online: 30 May 2024; doi:10.1038/s41560-024-01551-5
A detailed understanding of defects in kesterite solar cells is still lacking. Shi et al. identify a key defect and its formation mechanism and use alloying to suppress it, achieving solar cells with 14.2% certified efficiency.
All-air-processed perovskite solar cells with efficiency of 24.45% are realized by incorporating an amphoteric Lewis acid–base (cephalothin) into PbI2 films, which induced PbI2 films with highly oriented layered plane. The highly layer-oriented PbI2 films enabled forming a high-quality perovskite film with moderate amount of residual PbI2 in air condition.
The two-step sequential deposition method exhibits favorable operability for processing perovskite films. Due to the growth of the perovskite films largely depends on the pre-deposited PbI2 films, the porous and rough PbI2 films are expected to facilitate the penetration of the organic amine salts. However, in air conditions, the porous and rough PbI2 films also facilitate the penetration of the water molecules, thus leading to diminished crystallinity. Despite substantial efforts aimed at inhibiting the decomposition of perovskite films, the performance of air-processed perovskite solar cells (PSCs) remains unsatisfactory. Herein, the study presents that the PbI2 films with high exposure of layered planes and vanished of non-layered planes have more effective to resist water erosion and promote the crystallization process of perovskite films. An amphoteric Lewis acid-base molecule (cephalothin, a type of antibiotic) is added in PbI2 precursor solution to induce this highly layer-oriented PbI2 film. Consequently, the perovskite films can be processed under humidity condition and yield the champion PSC with an outstanding power conversion efficiency of 24.45%. In addition, the unencapsulated devices maintain 80% of their initial power conversion efficiency after 1000 h storage in air and exhibit high thermal stability after 100 cycles at 25–70 °C.
Pb-S bond is successfully incorporated into CsPbI3 surface with zwitterionic organosulfide perovskite of [CYS][PbCl2]. [CYS][PbCl2] owns a larger bandgap and shallower fermi level, constructing a type-II interfacial heterojunction with CsPbI3. Besides, the robust Pb-S covalency in [CYS][PbCl2] will stabilize CsPbI3 beneath. Resulting inverted PSCs exhibit high Voc of over 1.20 V and efficiency of 20.38% with good moisture or operational stability.
Here robust Pb-S covalency is successfully incorporated into CsPbI3 heterojunction by introducing a new zwitterionic organosulfide-halide perovskite on top of CsPbI3. Cysteamine (CYS: +NH3(CH2)2S−) will react with PbCl2 and form a new 3D perovskite with much shallower fermi level on CsPbI3 surface, constructing an efficient CsPbI3/[CYS][PbCl2] heterojunction. As a result, interfacial energy loss can be significantly inhibited and device open-circuit voltage (Voc) is increased to over 1.20 V with champion efficiency of 20.38% in inverted CsPbI3 perovskite solar cells (PSCs). Besides, the intrinsic moisture and phase stability of [CYS][PbCl2] perovskite will effectively stabilize the CsPbI3 beneath owing to its robust Pb-S covalency. PSCs with [CYS][PbCl2] exhibit significantly improved stability, whether in moist air or under continuous maximum power point (MPP) tracking.
