Chen Weijie

This study introduces BO-AM-4F, a novel non-fullerene acceptor using an asymmetric strategy to incorporate amide alkyl chains. This design enhances molecular packing and crystallinity. Combined with PBDB-TF and eco-friendly processing, BO-AM-4F-based organic photovoltaics achieve 18.0% efficiency, demonstrating excellent light and thermal stability, advancing sustainable photovoltaic technology.

Abstract

Recent advancements in organic photovoltaic (OPV) cells have resulted in power conversion efficiencies (PCEs) surpassing 20%. However, the use of halogen solvents in the fabrication of OPV cells raises concerns due to their potential environmental and health impacts. In this work, a novel non-fullerene small molecule acceptor BO-AM-4F, featuring an asymmetric alkyl chain design that includes a 2-butyloctyl and a unique 6-(hexylamino)-6-oxohexyl chain is synthesized. This design significantly improves molecular packing, crystallinity, and electrostatic potential distribution compared to the controlled acceptor DBO-4F, which possesses symmetric 2-butyloctyl chains. When combined with the polymer donor PBDB-TF and processed using the non-halogen solvent o-xylene, the BO-AM-4F-based OPV cell achieves an impressive PCE of 18.0%, surpassing the 16.6% PCE observed in the PBDB-TF:DBO-4F device. Furthermore, the PBDB-TF:BO-AM-4F system demonstrates enhanced photostability and thermal stability compared to its DBO-4F counterpart. These findings emphasize asymmetric alkyl chain engineering as an effective strategy for developing high-performance, environmentally friendly OPV materials. This represents a significant step towards sustainable OPV technology.

A novel tert-butyl-functionalized phosphonic acid carbazole SAM (tBu-4PACz) improves hole extraction in inverted perovskite solar cells (PSCs), reducing aggregation and enhancing layer uniformity. This mixed SAM system achieves a power conversion efficiency (PCE) of 26.25% with over 86% fill factors, maintaining 94.7% efficiency after 500 hours of continuous testing under simulated sunlight.

Abstract

Self-assembled monolayers (SAMs) are employed as hole-selective contacts in inverted perovskite solar cells (PSCs) and have achieved record power conversion efficiency (PCE) over 26%. However, the tendency of extensively employed SAM [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid to aggregate leads to its uneven coverage to the transparent conducting oxide substrate, which subsequently compromises the photovoltaic performance. Herein, a novel tert-butyl functionalized phosphonic acid carbazole SAM is developed, i.e., (4-(3,6-di-tert-butyl-9H-carbazol-9-yl)butyl)phosphonic acid (tBu-4PACz), and introduced to a mixed SAM system as the hole-extraction layer in inverted PSCs. The stereo-hindrance of the bulky tert-butyl group prevents undesired aggregation and leads to better conformality, which facilitates more efficient hole-extraction and suppresses interfacial recombination losses. The tBu-4PACz SAM-based inverted PSC has achieved record level PCE of 26.25% (26.21%, certificated) with outstanding fill factors over 86%. Moreover, the mixed SAM based inverted PSC devices maintained over 94.7% of their initial efficiency after 500 h continuous maximum power-point tracking under simulation 1-sun irradiation.

Publication date: 19 February 2025

Source: Joule, Volume 9, Issue 2

Author(s): Biao Li, Yuxin Yao, Chenxia Kan, Pengjie Hang, Jiangsheng Xie, Qixin Yin, Daoyong Zhang, Xuegong Yu, Deren Yang

Publication date: 15 January 2025

Source: Joule, Volume 9, Issue 1

Author(s): Yun Seop Shin, Ji Won Song, Dong Gyu Lee, Jaehwi Lee, Jongdeuk Seo, Jina Roe, Gwang Yong Shin, Dongshin Kim, Jiwoo Yeop, Dongmin Lee, Minjin Kim, Yimhyun Jo, Hyungsu Jang, Jung Geon Son, Woojin Lee, Jeongmin Son, Sujung Park, Shinuk Cho, Tae Joo Shin, Gi-Hwan Kim

Phase-pure dopant-free α-FAPbI₃ perovskite films are being prepared by hot-press assisted annealing at 300 °C. Higher temperature can promote the transformation of δ-FAPbI₃ to α-FAPbI₃, induce recrystallization to relieve strain. The applied pressure creates a confined space that effectively prevents the volatilization of organic components in perovskite. The result solar cell achieves a PCE of 24.06% and demonstrates ultra-high damp-heat stability.

Abstract

High temperatures facilitate the formation of stable, high-crystallinity α-FAPbI₃ films but can lead to the volatilization of organic components in perovskites. Here, a 300 °C hot-press-assisted recrystallization strategy is reported to grow stable phase-pure α-FAPbI₃ film without any dopants. High temperature can promote the transformation of δ-FAPbI₃ to α-FAPbI₃, and induces recrystallization to relieve strain. The applied pressure creates a confined space that effectively prevents the volatilization of organic components in perovskite. The α-FAPbI₃ film prepared by hot-press at 300 °C achieves an average grain size of ≈3 µm (with grains up to 10 µm) and demonstrates excellent damp-heat stability, showing no significant change after 20 s in deionized water. The result solar cell delivers a power conversion efficiency as high as 24.06% and retains >70% of their initial efficiency value after 1000 h at 85 °C and 85% relative humidity.

Here, through the effective passivation of thick film defects in perovskite by employing the RbX addition strategy, the crystalline quality, enhances the device performance of bifacial perovskite solar cells (PSCs), positioning them at the forefront of current research in this field. The front photovoltaic conversion efficiency reaches 21.04%, with a bifaciality of ≈80%, achieving an power generation density (PGD) of 24.36 mW cm^{− 2} at a albedo of 0.2.

Abstract

Bifacial perovskite solar cells (PSCs) possess a dual light-absorbing structure, which enables higher power output at lower additional costs. However, the replacement of metal electrodes with transparent ones leads to serious light loss, necessitating a thicker perovskite layer to compensate for this drawback. In this study, the impact of different rubidium halide (RbCl, RbBr, and RbI) additives is systematically investigated on precursor solubility and the quality of micron-sized perovskite thick films prepared using a two-step method. It is observed that RbCl exhibited the strongest interactions with PbI₂, enhancing its solubility and leading to the formation of multihole PbI₂ films that promote subsequent crystallization of thick perovskite film. Additionally, the RbCl-based perovskite film demonstrates a narrowed bandgap attributed to the formation of a-FAPbI₃. Consequently, the short-circuit current density (J_sc ) and open-circuit voltage (V_oc ) in the RbCl-based bifacial PSCs are simultaneously enhanced, and a record efficiency of 20.86% (21.04% certified) is also obtained among n-i-p bifacial PSCs, exhibiting an ≈80% bifaciality and a power generation density (PGD) exceeding 24 mW cm⁻² with a reflectivity value of 0.2. More importantly, the optimized device does not show any performance degradation after continuous illumination under 1sun for 1000 h.

A novel approach, called “protonation-induced localized transformation of 2D perovskites”, is proposed to convert disordered, randomly oriented layered 2D perovskites into more favorable vertically oriented ones at grain boundaries. This method addresses the challenges of poor carrier mobility and conductivity at 2D/3D heterojunctions, simultaneously enhancing both the efficiency and stability of photovoltaic devices.

Abstract

Dimensional engineering is promising for achieving a high power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). However, insulated organic spacers in 2D perovskites often severely hinder carrier transport between the internal layers of devices. Herein, the “protonation-induced localized transformation of 2D perovskites” is proposed to overcome the low carrier transport and conductivity of 2D/3D perovskite heterojunctions. Metformin, with its multiple amine groups and a substantial difference between its pKa value and perovskites, is protonated in an acidic environment or directly converted into the hydrochloride salt for the surface passivation of methylammonium lead iodide. This leads to the transformation of disorderedly oriented layered 2D perovskite into vertically oriented ones at grain boundaries. Consequently, the PCE of a carbon-based PSC treated by protonated metformin increased considerably, reaching an optimal level of 14.13%. Additionally, applying this passivation strategy to a planar device (ITO/4PADCP/perovskite/PCBM/BCP/Ag) increased PCE from 20.82% to 22.09%, confirming the applicability of the strategy. To demonstrate the practical stability, an integrated PSC–supercapacitor device is assembled, which shows good cycling stability. This article introduces a novel method to improve carrier transport in 2D/3D perovskite heterojunctions, promoting the extensive utilization of dimensional engineering.

A series of self-assembled molecules, namely t-Bu-3PACz, Ph-3PACz, and Bz-3PACz, are synthesized and investigated in organic solar cells (OSCs). Among them, the twisted phenyl groups ensure excellent solubility and sufficient intermolecular interaction to fine-tune the self-assembled behavior. Therefore, the device based on Ph-3PACz exhibits a superior power conversion efficiency (PCE) of 19.2% in PM6:eC9-based binary OSCs.

Abstract

P-type carbazole-derived self-assembled monolayers (SAMs) have garnered significant attention as promising hole transport layers (HTLs) in the development of highly efficient organic solar cells (OSCs). However, it still lacks the effective navigation to modulate the terminal functional groups of SAMs to achieve a compromise between the highest occupied molecular orbital (HOMO) energy levels and self-aggregation behavior. Herein, the terminal functional groups are adjusted and three SAMs are synthesized, namely, t-Bu-3PACz, Ph-3PACz, and Bz-3PACz to comprehensively investigate their intrinsic properties and influence on photovoltaic performance. Among them, Ph-3PACz featuring an exceptionally suitable conjugated region and steric hindrance exhibits the best compatibility with the active layer, superior electrical conductivity, HOMO energy level aligning with polymer donor, and ordered film packing. As a result, the photovoltaic devices based on Ph-3PACz exhibit an open-circuit voltage (V_OC ) of 0.850 V, a short-circuit current density (J_SC ) of 28.7 mA cm^−2, and a fill factor (FF) of 78.5%, thus resulting in a remarkable power conversion efficiency (PCE) of 19.2%. This work provides an effective and easily navigable method to modulate the molecular packing and energy levels of SAMs, thereby achieving highly efficient OSCs.

The PTFE is introduced as an effective internal encapsulation layer between the perovskite film and the electron transport layer in the inverted PSCs. As a result, the optimized PTFE-based device achieved an impressive champion PCE of 25.49%. Additionally, the internally encapsulated perovskite device effectively prevents ion migration and water erosion, demonstrating excellent long-term stability even without external encapsulation.

Abstract

Perovskite solar cells (PSCs) have made significant strides in efficiency, but their long-term stability remains a challenge. While external encapsulation mitigates extrinsic degradation and lead leakage, it does not fully address performance decline due to ion migration within the perovskite devices. Therefore, an internal encapsulation layer that can selectively transport charge carriers and suppress ion migration across the interface is of great significance for achieving long-term stability in these devices. Here, polytetrafluoroethylene (PTFE) can serve as an effective internal encapsulation layer between the perovskite film and the electron transport layer in the inverted PSCs is demonstrated. The PTFE layer can selectively transport electrons and suppress ion diffusion, resulting in a higher power conversion efficiency (PCE) of 25.49% compared to 24.74% of the control devices and much better long-term stability. Even after 1500 h of air exposure, the internal encapsulated perovskite devices can maintain 92.6% of their original PCE, outperforming the control devices at 80.4%. This approach offers a novel solution for addressing ion migration-induced instability in perovskite devices.

Two well-compatible dimeric acceptors, DC9-HD and DYSe-3, are utilized to fabricate ternary organic solar cells. The incorporation of red-shifted DYSe-3 into the PM6:DC9-HD binary blend optimize the morphologies and suppressed charge recombination. This, combined with their long exciton diffusion length and low voltage loss, contributes to an impressive efficiency of 19.4% for PM6:DC9-HD:DYSe-3 ternary devices.

Abstract

To enhance the performance of dimeric acceptors (DMAs) based organic solar cells (OSCs), two new DMAs, designated as DC9-HD and DYSe-3, are rationally developed and employed to fabricate ternary OSCs. The substitution of the sulfur atom on the outer ring of the fused-ring core of DC9-HD with a selenium atom resultes in the red-shifted DYSe-3. Despite these minor differences, DC9-HD and DYSe-3 possess nearly identical conjugated skeletons, which contribute to their similar packing motifs and crystallinities, ultimately enabling a high degree of miscibility between two DMAs. Upon incorporating DYSe-3 into the host PM6:DC9-HD binary blend, fibril-like morphologies featured with diameters of ≈16.9 nm and reduced charge recombination are observed in the PM6:DC9-HD:DYSe-3 ternary blend. More importantly, owing to their long exciton diffusion lengths and low voltage losses, a remarkable power conversion efficiency of 19.4% is achieved for the ternary OSCs, alongside a delicate balance between open-circuit voltage and short-circuit current density. This super result is comparable to the best performance of oligomer acceptor based OSCs reported to date. Furthermore, the proposed ternary strategy, which combines one polymer donor and two well-compatible DMAs, not only retains the advantages of DMAs but also offers a streamlined approach for fabricating high-performance ternary OSCs.

Polymeric charge transporters hold immense potential for inverted perovskite solar cells due to their tunable structures, high conductivity, and inherent flexibility. This review comprehensively explores recent advancements in these polymeric materials, while also delving into the remaining challenges and proposing practical design strategies for their future optimization.

Abstract

Inverted perovskite solar cells (PSCs) hold exceptional promise as next-generation photovoltaic technology, where both perovskite absorbers and charge-transporting materials (CTMs) play critical roles in cell performance. In recent years, polymeric CTMs have played an important role in developing efficient, stable, and large-area inverted PSCs due to their unique properties of high conductivity, tunable structures, and mechanical flexibility. This review provides a comprehensive overview of polymeric CTMs used in inverted PSCs, encompassing polymeric hole transport materials (HTMs) and electron transport materials (ETMs). the relationship between their molecular structures, modification strategies are systematically summarized and analyzed for adjusting energy levels, and improving charge extraction, enabling a deep understanding of these widely used materials. The review also explores effective strategies for designing even more efficient polymeric CTMs. Finally, an outlook is proposed on the exciting research of novel polymeric CTMs, paving the way for their commercialized applications in PSCs.

Stepwise melting-polymerizing molecule (SMPM) additive enables grain-scale encapsulated perovskite, achieving highly water-resistant perovskite solar cells (PSCs) with 25.21% efficiency and over 2000h T₉₅ stability under 85% relative humidity. Unencapsulated SMPM-PSCs even operate underwater and show effectively suppressed Pb-leakage, potentially solving stability and environmental concerns for PSC commercialization.

Abstract

Despite the ongoing increase in the efficiency of perovskite solar cells, the stability issues of perovskite have been a significant hindrance to its commercialization. In response to this challenge, a stepwise melting-polymerizing molecule (SMPM) is designed as an additive into FAPbI₃ perovskite. SMPM undergoes a three-stage phase transition during the perovskite annealing process: initially melting from solid to liquid state, followed by overflowing grain boundaries, and finally self-polymerizing to form a hydrophobic grain-scale encapsulation in perovskite solar cells, providing protection against humidity-induced degradation. With this unique property, coupled with the advantages of improved crystallization, diminished non-radiative recombination, and energy level alignment, FAPbI₃-based perovskite solar cells with a 25.21% (small-area) and 22.94% (1 cm²) power conversion efficiency and over 2000 h T95% stability under 85% relative humidity is achieved. Furthermore, the SMPM-based perovskite solar cells without external encapsulations sustain impressive stability during underwater operation, in which the black FAPbI₃ phase is maintained and Pb-leakage is also effectively suppressed. Therefore, the SMPM strategy can offer a sustainable settlement in both stability and environmental issues for the commercialization of perovskite solar cells.

Halogenated polycyclic aromatic hydrocarbon has a dipole moment, useful for treating hole selective layer to provide interface modification and passivation for high bandgap p–i–n perovskite solar cells. First demonstrations utilizing such technique of 1.78 eV bandgap perovskite and perovskite-OPV tandem solar cells produce record fill factors.

Abstract

Perovskite whentandemed with organic photovoltaics (OPV) for double-junctions have efficiencypotentials over 40%. However, there is still room for improvement suchas better current matching, higher fill factor, as well as lower voltage and fill factor losses in the top perovskite cell. Here weaddress the issue associated with the top perovskite cell by utilising anovel halogenated polycyclic aromatic hydrocarbon compound, 1-naphthylammoniumchloride (NA─Cl) playing dual roles of surface modification for the hole selectivelayer (HSL) and passivation of HSL/perovskiteinterface. Results of X-ray photoelectron spectroscopy and density functionaltheory calculations reveal that NA─Cl retains self-assembly property for the HSLwhile demonstrating high dipole moment and polarizability. This induces asurface dipole at the HSL/perovskite interface reducing the energetic barrierfor hole extraction by 210 meV thereby enhancing voltage output and fill factorof the device. Such scheme when implemented in a high bandgap (1.78 eV)perovskite solar cell, results in a respectable efficiency of 19.7% and thehighest fill factor of 85.4% amongst those of 1.78 eV perovskite cells reported.We have also achieved 23% cell efficient monolithic perovskite-OPV tandem withan impressive fill factor of 84%, which is the highest for perovskite-OPVtandem cells reported to-date.

In this work, a completely fused non-fullerene acceptor, GS-20 is synthesized, with strong aggregation properties. GS-20 can be utilized as a third component to accelerate aggregation process and modulate aggregation structure. Consequently, the ternary OPV cell achieves a maximum PCE of 19.0% without any post-treatments, which is also feasible for the fabrication of postprocessing-free OPV modules.

Abstract

The photovoltaic performance of organic photovoltaic (OPV) cells can be significantly improved by regulating the aggregation structure and film formation kinetics of the constituent materials. However, many regulation strategies, including the use of additives and annealing, require complex fabrication processes and additional investments, which poses challenges for the industrialization of OPV cells. In this work, a completely fused non-fullerene acceptor, GS-20 is designed and synthesized, with strong aggregation properties. The incorporation of GS-20 as a third component into the PBQx-TF:eC9-2Cl-based cell accelerates aggregation of eC9-2Cl and improves molecular stacking by promoting film deposition. The as-cast ternary OPV cells fabricated without any post-treatments exhibited a high V _OC of 0.890 V and a maximum PCE of 19.0%. Moreover, a postprocessing-free OPV module is fabricated using the blade coating method and obtains a satisfactory PCE of 13.5%, indicating excellent feasibility for large-scale preparation. This work realizes an efficient postprocessing-free OPV cell through molecular design and ternary strategy, facilitating the industrialization of OPV technology.

Two donor–acceptor covalent organic frameworks are developed to control the perovskite energy level and defects at the buried interface of inverted devices. The power conversion efficiency is improved to 25.68% for conventional bandgap devices and 22.92% for wide-bandgap devices. Additionally, these cells demonstrated excellent stability, establishing a solid foundation for the commercialization of perovskite/silicon tandem solar cells.

Abstract

Simultaneously controlling defects and film morphology at the buried interface is a promising approach to improve the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs). Here, two new donor‒acceptor type semiconductive covalent organic frameworks (COFs) are developed, COF_TPA and COF_ICZ. The carefully designed COFs structure not only effectively regulates the morphology and defects of the buried interface film, but also realizes the alignment with the energy level of the perovskite film and enhances the extraction and transmission of the interface charge. Among them, COF_ICZ-treated inverted PSCs achieved a maxmum PCE of 25.68% (certified 25.14%), the inverted PCE reached a minimum PCE of 22.92% for 1 cm² device. The efficiency of inverted PSCs with a 1.68 eV wide bandgap reached 22.92%, which is the highest datum of the reported 1.68 eV wide bandgap PSC. This lays the groundwork for the commercialization of perovskite/silicon tandem solar cells. Additionally, the unencapsulated devices demonstrated a high degree of stability during operational use and when subjected to conditions of high humidity and temperature.

A quasi-2D/3D heterojunction-based WBG perovskite is constructed to repair the surface defects and weaken the quantum-well confinement effect. These advances reduce interfacial carrier transport loss, contributing to balanced carrier recombination in the interconnecting layer. The resulting perovskite/organic tandems exhibit record power conversion efficiencies of 25.92% (0.0628 cm²) and 24.63% (1.004 cm²), as well as robust operational stability.

Abstract

Wide-bandgap (WBG) perovskites are continuously in the limelight owing to their applicability in tandem solar cells. The main bottlenecks of WBG perovskites are interfacial non-radiative recombination and carrier transport loss caused by interfacial defects and large energy-level offsets, which induce additional energy losses when WBG perovskites are stacked with organic solar cells in series because of unbalanced carrier recombination in interconnecting layer (ICL). To solve these issues, 1,3-propanediammonium iodide (PDADI) is incorporated to form Dion–Jacobson -phase quasi-2D perovskites with mixed high-n-values in WBG perovskites. PDADI simultaneously repairs the shallow/deep defects and establishes a Type-II energy-level alignment between quasi-2D/3D and 3D perovskites for rapid carrier extraction. More importantly, the short-chain diammonium cation in quasi-2D perovskite with high n-values results in a short Pb–I inorganic layer spacing, which enhances the interlayer electronic coupling and weakens the quantum-well confinement effect that restricts carrier transport. The suppressed transport loss increases the electron concentration in the ICL for balanced carrier recombination. The 0.0628 and 1.004 cm² perovskite/organic tandems achieve remarkable efficiencies of 25.92% and 24.63%, respectively. The quasi-2D capping layer can inhibit ion migration, allowing perovskite/organic tandems to show excellent operational stability (T ₈₅ > 1000 h).

Publication date: March 2025

Source: Journal of Energy Chemistry, Volume 102

Author(s): Shuai Zeng, Hui Wang, Xiangyang Li, Hailin Guo, Linfeng Dong, Chuanhang Guo, Zhenghong Chen, Jinpeng Zhou, Yuandong Sun, Wei Sun, Liyan Yang, Wei Li, Dan Liu, Tao Wang

This work demonstrates the use of 1,4-bis(aminomethyl)benzene (PDMA) to enhance the efficiency and stability of wide-bandgap perovskite solar cells. By simultaneously forming a grooved perovskite surface to increase the contact area with electron transport layer and passivating the defects, the PDMA treatment achieves a power conversion efficiency of 21.23% owing to improved charge transfer and reduced nonradiative recombination.

Wide-bandgap perovskite solar cells (WBG-PSCs) are pivotal in achieving high-performance tandem solar cells. However, their power conversion efficiency (PCE) is limited by the losses from the interfacial charge transfer barrier and nonradiative recombination. In this investigation, 1,4-bis(aminomethyl)benzene (PDMA) is employed as a defect passivator for fabricating methylammonium (MA)-free perovskite solar cells (PSCs), thus effectively mitigating nonradiative recombination losses of charge carriers. Meanwhile, PDMA molecules chemically rinse the perovskite film to create a grooved surface, leading to the increase of contact area between the perovskite and electron transport layer to further improve the interfacial charge transfer. As a result, the PSCs based on these surface-passivated and chemically cleaned perovskite films present a champion PCE of 21.23% (E _g = 1.68 eV) compared to the control devices with a PCE of 18.23%, while maintaining over 80% efficiency after 800 h storage in ambient air. This study presents a highly effective approach for one-step passivation and chemical cleaning of wide-bandgap perovskite for efficient and stable solar cells, offering valuable insights for future research in this field.

By delicately rebuilding peripheral F, Cl, Br footprints, the central brominated acceptor of CH−B afforded the first-class efficiency of 19.78 % for binary organic solar cells, also achieved the best performance when further increasing active layer thickness to ~300 nm.

Abstract

Given homomorphic fluorine (F), chlorine (Cl) and bromine (Br) atoms are featured with gradually enlarged polarizability/atomic radius but decreased electronegativity, the rational screen of halogen species and locations on small molecular acceptors (SMAs) is quite essential for acquiring desirable molecular packing to boost efficiency of organic solar cells (OSCs). Herein, three isomeric SMAs (CH−F, CH−C and CH−B) are constructed by delicately rebuilding peripheral F, Cl, Br footprints on both central and end units. Such a re-permutation of peripheral halogens could not only maintain the structural symmetry of SMAs to the maximum, but also acquire extra asymmetric benefits of enhanced dipole moment and intramolecular charge transfer, etc. Moreover, central brominating enhances molecular crystallinity of CH−B without introducing undesirable steric hindrance on end groups, thus rendering a better balance between high crystallization and domain size control in PM6:CH−B blend. Further benefitting from the large dielectric constant, small exciton binding energy, optimized molecular packing and great electron transfer integral, CH−B affords the first class binary OSC efficiency of 19.78 %, moreover, the highest efficiency of 18.35 % thus far when increasing active layer thickness to ~300 nm. Our successful screening in rebuilding peripheral halogen footprints provides the valuable insight into further rational design of SMAs for record-breaking OSCs.

N-type Semiconductors can optimize the top interface of inverted perovskite solar cells (i-PSCs) and modules (i-PSMs) without negatively affecting the underlying perovskite layer, effectively enhancing the device efficiency and stability. Consequently, a remarkable efficiency of 25.82% was obtained for Y7-BO-based i-PSCs, and record efficiencies of 23.06%, 22.32%, 21.10% were achieved from Y7-BO-based i-PSMs with 50 cm², 400 cm², 1160 cm² areas, respectively, along with superior stability.

Abstract

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i-PPVs). Herein, non-fullerene acceptors (NFAs), known as Y6-BO and Y7-BO, were utilized to modify the perovskite/ETL interface in i-PPVs. Non-polar solvent-soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved phenyl-C61-butyric acid methyl ester (PCBM) ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6-BO and Y7-BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i-PSC) modified with Y7-BO reaches 25.82 %. Moreover, the adoption of non-polar solvents and the superior semiconductor properties of Y7-BO molecules also enable perovskite solar modules (i-PSM) with effective areas of 50 cm², 400 cm², and 1160 cm² to achieve record efficiencies of 23.05 %, 22.32 %, and 21.1 % (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7-BO maintained 94.4 % of the initial efficiency after 1522 hours of maximum power point aging.

In this work, the surface energy state of the SnO₂ buried interface was modulated by proton precompensation treatment, which can inhibit the proton transfer behavior guided by proton affinity and enhance the stability of perovskite crystal, achieving efficient perovskite solar cells with significantly improved photothermal stability.

Abstract

The chemical property of the buried interface plays a crucial role in improving the performance and stability of perovskite solar cells (PSCs). The SnO₂/perovskite interface prepared from SnO₂ alkaline hydrogel with high proton affinity triggers directional migration and irreversible reactions of protons, exacerbating the disintegration of perovskite crystal. In this study, we proposed proton precompensation strategy to suppress the deprotonation effect of the buried interface and improve the durability of the devices. By modulating the chemical environment and surface energy state of the buried interface, the domain-limiting and spontaneous compensation of protons in formamidinium (FA⁺) under coulomb force were achieved, thereby stabilizing the perovskite crystal structure. The stability of target perovskite films under UV illumination and heating at 85 °C was significantly enhanced. As a result, the devices can retain around 90 % of their initial power conversion efficiency (PCE) after 1000 h of continuous irradiation at the maximum power point (MPP). Moreover, due to the reduction of defect content at the buried interface and the improvement of conductivity and carrier mobility by the precompensation treatment, the interfacial energy loss and non-radiative recombination were substantially diminished. The target PSC devices exhibited much higher PCE of 25.55 % than the control devices (23.03 %).

Nature Energy, Published online: 12 November 2024; doi:10.1038/s41560-024-01667-8