JIALINGBO

Phosphorylcholine chloride and Me-4PACz are used to form Co-SAM on the NiO _x surface to optimize the buried interface in PSCs. Co-SAM can promote the growth of perovskite crystals, passivate buried defects, optimize the energy band alignment, and relieve the residual stress of the perovskite film, leading to power conversion efficiencies as high as 25.09% and excellent device stability.

Abstract

[4-(3,6-dimethyl-9H-carbazol-9yl)butyl]phosphonic acid (Me-4PACz) self-assembled molecules (SAM) are an effective method to solve the problem of the buried interface of NiO _x in inverted perovskite solar cells (PSCs). However, the Me-4PACz end group (carbazole core) cannot forcefully passivate defects at the bottom of the perovskite film. Here, a Co-SAM strategy is employed to modify the buried interface of PSCs. Me-4PACz is doped with phosphorylcholine chloride (PC) to form a Co-SAM to improve the monolayer coverage and reduce leakage current. The phosphate group and chloride ions (Cl⁻) in PC can inhibit NiO _x surface defects. Meantime, the quaternary ammonium ions and Cl⁻ in PC can fill organic cations and halogen vacancies in the perovskite film to enable defects passivation. Moreover, Co-SAM can promote the growth of perovskite crystals, collaboratively solve the problem of buried defects, suppress nonradiative recombination, accelerate carrier transmission, and relieve the residual stress of the perovskite film. Consequently, the Co-SAM modified devices show power conversion efficiencies as high as 25.09% as well as excellent device stability with 93% initial efficiency after 1000 h of operation under one-sun illumination. This work demonstrates the novel approach for enhancing the performance and stability of PSCs by modifying Co-SAM on NiO _x .

Publication date: April 2024

Source: Nano Energy, Volume 122

Author(s): Li-Rong Zeng, Bin Ding, Gao Zhang, Yan Liu, Xin Zhang, Guan-Jun Yang, Bo Chen

PSCs are prepared by doping choline chloride (CC), acetylcholine chloride (AC), phosphocholine chloride sodium salt (PCSS) into SnO₂ dispersion. These dopants can act as bridge through synergistic effects to form uniform ETL morphology, enhance the interface contact, and passivate defects. Ultimately, the device with SnO₂-PCSS ETL achieves a champion PCE of 23.06% and an ideal voltage of 1.2 V.

Abstract

The interfacial carrier non-radiative recombination caused by buried defects in electron transport layer (ETL) material and the energy barrier severely hinders further improvement in efficiency and stability of perovskite solar cells (PSCs). In this study, the effect of the SnO₂ ETL doped with choline chloride (CC), acetylcholine chloride (AC), and phosphocholine chloride sodium salt (PCSS) are investigated. These dopants modify the interface between SnO₂ ETL and perovskite layer, acting as a bridge through synergistic effects to form uniform ETL films, enhance the interface contact, and passivate defects. Ultimately, compared with CC (which with ─OH) and AC (which with C═O), the PCSS with P═O and sodium ions groups is more beneficial for improving performance. The device based on PCSS-doped SnO₂ ETL achieves an efficiency of 23.06% with a high V_OC of 1.2 V, which is considerably higher than the control device (20.55%). Moreover, after aging for 500 h at a temperature of 25 °C and relative humidity (RH) of 30–40%, the unsealed device based on SnO₂-PCSS ETL maintains 94% of its initial efficiency, while the control device only 80%. This study provides a meaningful reference for the design and selection of ideal pre-buried additive molecules.

As a pivotal component within solar devices, the electrode has a profound impact on the device performance. Herein, device configuration based on the physically and chemically stable molybdenum electrode is engineered to fundamentally tackle the instability factors introduced by electrodes in perovskite solar cells. A titanium seed layer is further introduced to optimize the electrode interfacial contact.

Abstract

Metal halide perovskite solar cells (PSCs) have garnered much attention in recent years. Despite the remarkable advancements in PSCs utilizing traditional metal electrodes, challenges such as stability concerns and elevated costs have necessitated the exploration of innovative electrode designs to facilitate industrial commercialization. Herein, a physically and chemically stable molybdenum (Mo) electrode is developed to fundamentally tackle the instability factors introduced by electrodes. The combined spatially resolved element analyses and theoretical study demonstrate the high diffusion barrier of Mo ions within the device. Structural and morphology characterization also reveals the negligible plastic deformation and halide-metal reaction during aging when Mo is in contact with perovskite (PVSK). The electrode/underlayer junction is further stabilized by a thin seed layer of titanium (Ti) to improve Mo film's uniformity and adhesion. Based on a corresponding p–i–n PSCs (ITO/PTAA/PVSK/C₆₀/SnO₂/ITO/Ti/Mo), the champion sample could deliver an efficiency of 22.25%, which is among the highest value for PSCs based on Mo electrodes. Meanwhile, the device shows negligible performance decay after 2000 h operation, and retains 91% of the initial value after 1300 h at 50–60 °C. In summary, the multilayer Mo electrode opens an effective avenue to all-round stable electrode design in high-performance PSCs.

Nature, Published online: 17 January 2024; doi:10.1038/s41586-023-06892-x

A novel constructing charge bridge path strategy is proposed to enhance charge extraction and interface contact at the interface of perovskite layer and electron transport layer in response to the severe current loss problem in tin-based photovoltaics. After the post-treatment of 3-AMBTh, the current density of the device is further improved, thereby increasing the efficiency of tin-based photovoltaics to 14.53%, which is also one of the best-performing devices in tin-based perovskite field.

Abstract

Tin-based perovskite solar cells (TPSCs) have attracted significant research interest due to their exceptional optoelectronic properties and environmentally friendly characteristics. However, TPSCs with ideal bandgap suffer from substantial current losses, necessitating the development of innovative interface engineering strategies to enhance device performance. In this study, an unprecedented approach constructing charge transfer path is presented by a simple post-growth treatment of 3-Aminomethylbenzo[b]thiophene (3-AMBTh) on the perovskite film. The selective reaction of 3-AMBTh with exposed FA+ on the perovskite surface suppresses the formation of iodine vacancy defects, leading to a reduction in trap density. Additionally, the residual aromatic rings on the surface form an effective π–π stacking interaction system with subsequently deposited ICBA, facilitating enhanced charge transfer at the interface. By harnessing the potential of the charge transfer path, the TPSCs exhibit remarkable device efficiency of up to 14.53%, positioning them among the top-performing TPSCs reported to date.

A benzothiophene-based SAM HSLMeO-BTBT is developed. Compared to the carbazole-based MeO-2PACz SAM, MeO-BTBT shows stronger intermolecular interactions, a passivation effect at the buried interface, and better photo-stability, enabling a robust HSL and stable perovskite bottom interface morphology. The devices with the MeO-BTBT HSL achieves a PCE of 24.53% with excellent long-term device stability under illumination and thermal stress.

Abstract

Effective passivation of defects at the buried interface between the perovskite absorber and hole-selective layer (HSL) is crucial for achieving high performance in inverted perovskite solar cells (PSCs). Additionally, the HSL needs to possess compact molecular packing and intrinsic photo- and thermo-stability to ensure long-term operation of the devices. In this study, a novel MeO-BTBT-based self-assembled monolayer (SAM) is reported to serve as an efficient HSL in inverted PSCs. Compared to the well-established carbazole-containing SAM MeO-2PACz, MeO-BTBT has flat and more extended conjugation with large atomic radius of the sulfur atom. These induce stronger intermolecular interactions to enable more ordered and compact SAM to be formed on indium–tin oxide (ITO) substrates. Meanwhile, the sulfur atoms in MeO-BTBT can coordinate with Pb²⁺ ions to passivate the defects at the buried interface of perovskite absorber. The derived perovskite films show both high photoluminescence (PL) quantum yield (13.2%) and a long lifetime (7.2 µs). The PSCs based on MeO-BTBT show a PCE of 24.53% with an impressive fill factor of 85.3%. The PCEs of MeO-BTBT-based devices can maintain ≈95% of their initial values after being aged at 65 °C for more than 1000 h or continuous operation under 1-sun illumination.

Efficient doping of hybrid perovskites holds the potential to further advance solar cell efficiency. This study presents a generic strategy for perovskite doping by constructing ultra-shallow near-edge states. These states can effectively prolong electron-hole recombination through efficient trap and de-trap processes, resulting in over 25% efficiency in inverted perovskite solar cells with superior long-term operational stability.

Abstract

Electronic band structure engineering of metal-halide perovskites (MHP) lies at the core of fundamental materials research and photovoltaic applications. However, reconfiguring the band structures in MHP for optimized electronic properties remains challenging. This article reports a generic strategy for constructing near-edge states to improve carrier properties, leading to enhanced device performances. The near-edge states are designed around the valence band edge using theoretical prediction and constructed through tailored material engineering. These states are experimentally revealed with activation energies of around 23 milli-electron volts by temperature-dependent time-resolved spectroscopy. Such small activation energies enable prolonged carrier lifetime with efficient carrier transition dynamics and low non-radiative recombination losses, as corroborated by the millisecond lifetimes of microwave conductivity. By constructing near-edge states in positive-intrinsic-negative inverted cells, a champion efficiency of 25.4% (25.0% certified) for a 0.07-cm² cell and 23.6% (22.7% certified) for a 1-cm² cell is achieved. The most stable encapsulated cell retains 90% of its initial efficiency after 1100 h of maximum power point tracking under one sun illumination (100 mW cm⁻²) at 65 °C in ambient air.

An ion-alloying strategy is reported to inhibit phase segregation in wide-bandgap perovskites by doping RbCl. Based on this strategy, a high steady-state power conversion efficiency (PCE) of 24.48% from perovskite/perovskite/c-Si triple-junction tandem is achieved, a giant leap from the previous PCE record and the highest certified efficiency among all types of perovskite-based triple-junction tandem solar cells.

Abstract

Wide-bandgap metal halide perovskites have demonstrated promise in multijunction photovoltaic (PV) cells. However, photoinduced phase segregation and the resultant low open-circuit voltage (V _oc) have greatly limited the PV performance of perovskite-based multijunction devices. Here, a alloying strategy is reported to achieve uniform distribution of triple cations and halides in wide-bandgap 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 single-junction 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 cm² photoactive area can be achieved in a perovskite/perovskite/c-Si triple-junction tandem cell, where the certification efficiency is by far the greatest performance of perovskite-based triple-junction tandem solar cells. This work overcomes the performance deadlock of perovskite-based triple-junction tandem cells by setting a materials-by-design paradigm.

Here, Ph-4PACz is designed and synthesized to achieve a stronger interface dipole layer and suitable energy level alignment, meanwhile, aluminum oxide nanoparticles (Al₂O₃-NPs) are introduced to enhance the substrate flatness and self-assembled monolayer (SAM) coverage, resulting in a conformal perovskite film with minimal gaps and energy loss at the buried interface. Hence, excellent performance is obtained in large-area devices.

Abstract

The efficiency loss caused by area scaling is one of the key factors hindering the industrial development of perovskite solar cells. The energy loss and contact issues in the buried interface are the main reasons. Here, a new self-assembled monolayer (SAM), Ph-4PACz, with a large dipole moment (2.32 D) is obtained . It is found that Ph-4PACz with high polarity can improve the band alignment and minimize the energy loss , resulting in an open-circuit voltage (V _oc) as high as 1.2 V for 1.55 eV perovskite. However, when applied to large-area devices, the fill factor (FF) still suffered from significant attenuation. Therefore, alumina nanoparticles (Al₂O₃-NPs) are introduced to the interface between Ph-4PACz and rough FTO substrate to further improve the flatness , resulting in a conformal perovskite film with almost no voids in the buried interface, thus promoting low exciton binding energy, fast hot-carrier extraction and low non-radiative recombination. The final devices achieved a small-area power conversion efficiency (PCE) of 25.60% and a large-area (1 cm²) PCE of 24.61% (certified at 24.48%), which represents one of the highest PCE for single device ≥ 1 cm² area. Additionally, mini-modules and stability testing are also carried out to demonstrate the feasibility of commercialization.

A porous insulating layer (PIL) made of self-assembled diphenylphosphinic acid (DPPA) is fabricated atop a perovskite film to address the challenge of balancing defect passivation and charge transport. Entire surface of perovskite film is well-passivated and energy level is modulated with DPPA treatment, and surplus DPPA forms PIL with submicrometer-scale openings, providing efficient charge transport pathways. The methylammonium-free perovskite devices with PIL structures exhibit enhanced efficiency and operational stability.

Abstract

In recent years, the surface modification of perovskite by wide band-gap insulating materials has been one of the main strategies to achieve efficient and stable perovskite solar cells (PSCs). Unfortunately, a significant hurdle in this approach is the dilemma surrounding the quality of passivation and the transport of charges. Here, this trade-off is overcome by introducing self-assembled diphenylphosphinic acid (DPPA) porous layer. Applying highly concentrated DPPA solution on the perovskite surface not only provides excellent passivation of entire surface, but also the excess DPPA will form a self-assembled porous insulating layer (PIL), which forms random submicron-sized openings at the interface of the insulating layer for accelerated charge transport. In addition, the energy level of the perovskite surface can be modulated by this insulating material to facilitate carrier transport. As a result, an impressive power conversion efficiency (PCE) over 24% has been achieved in methylammonium-free p-i-n devices with an ultrahigh fill factor (FF) of 84.7%. The unencapsulated devices exhibit excellent thermal and operational stability. This work paves a way for establishment of an effective passivation and facilitated transport simultaneously.

A conjugated phosphonic acid is developed to modify Spiro-OMeTAD benchmark HTL, leading to superior charge conductivity, reinforced ion immobilization, and remarkable device stability.

Abstract

High efficiency and long-term stability are the prerequisites for the commercialization of perovskite solar cells (PSCs). However, inadequate and non-uniform doping of hole transport layers (HTLs) still limits the efficiency improvements, while the intrinsic instability of HTLs caused by ion migration and accumulation is difficult to be addressed by external encapsulation. Here it is shown that the addition of a conjugated phosphonic acid (CPA) to the Spiro-OMeTAD benchmark HTL can greatly enhance the device efficiency and intrinsic stability. Featuring an optimal diprotic-acid structure, indolo(3,2-b)carbazole-5,11-diylbis(butane-4,1-diyl) bis(phosphonic acid) (BCZ) is developed to promote morphological uniformity and mitigate ion migration across both perovskite/HTL and HTL/Ag interfaces, leading to superior charge conductivity, reinforced ion immobilization, and remarkable film stability. The dramatically improved interfacial charge collection endows BCZ-based n-i-p PSCs with a champion power conversion efficiency of 24.51%. More encouragingly, the BCZ-based devices demonstrate remarkable stability under harsh environmental conditions by retaining 90% of initial efficiency after 3000 h in air storage. This work paves the way for further developing robust organic HTLs for optoelectronic devices.

This study examines the extensive metal halide perovskite device data compiled in the Perovskite Database, comprising more than 40,000 devices. The collective efforts of over a decade of perovskite research enable the identification of overarching trends in higher bandgap devices. Increasing efficiency loss with bandgap is attributed to mismatched transport materials, compositional inhomogeneity, and suboptimal optoelectronic absorber quality.

Abstract

Metal halide perovskites (MHPs) have become a widely studied class of semiconductors for various optoelectronic devices. The possibility to tune their bandgap (E _g) over a broad spectral range from 1.2 eV to 3 eV by compositional engineering makes them particularly attractive for light emitting devices and multi-junction solar cells. In this metadata study, data from Peer-reviewed publications available in the Perovskite Database (www.perovskitedatabase.com) is used to evaluate the current state of E _g tuning in wide E _g MHP semiconductors. Recent literature on wide E _g MHP semiconductors is examined and the data is extracted and uploaded onto the Perovskite Database. Beyond describing recent highlights and scientific breakthroughs, general trends are drawn from 45,000 individual experimental datasets of MHP solar cell devices. The historical evolution of MHP solar cells is recapitulated, and general conclusions are drawn about the current limits of device performance. Three dominant causes are identified and discussed for the degradation of performance relative to the Shockley-Queisser (SQ) model's theoretical limit for single-junction solar cells: 1) energetically mismatched selective transport materials for wide Eg MHPs, 2) lower optoelectronic quality of wide E _g MHP absorbers, and 3) dynamically evolving compositional heterogeneity due to light-induced phase segregation phenomena.

We synthesized poly(ionic liquid)s to craft a hydrophobic hydrogen-bonded polymer network that passivates the wide-band gap perovskite/electron transport layer interface and inhibits ion migration. The optimized devices achieve impressive efficiencies with outstanding thermostability and humidity resistance. The textured perovskite/Si tandem cell also reaches a remarkable champion efficiency maintaining exceptional operational stability.

Abstract

The pursuit of highly efficient and stable wide-band gap (WBG) perovskite solar cells (PSCs), especially for monolithic perovskite/silicon tandem devices, is a key focus in achieving the commercialization of perovskite photovoltaics. In this study, we initially designed poly(ionic liquid)s (PILs) with varying alkyl chain lengths based on density functional theory calculations. Results pinpoint that PILs with longer alkyl chain lengths tend to exhibit more robust binding energy with the perovskite structure. Then we synthesized the PILs to craft a hydrophobic hydrogen-bonded polymer network (HHPN) that passivates the WBG perovskite/electron transport layer interface, inhibits ion migration and serves as a barrier layer against water and oxygen ingression. Accordingly, the HHPN effectively curbs nonradiative recombination losses while facilitating efficient carrier transport, resulting in substantially enhanced open-circuit voltage (V _oc) and fill factor. As a result, the optimized single-junction WBG PSC achieves an impressive efficiency of 23.18 %, with V _oc as high as 1.25 V, which is the highest reported for WBG (over 1.67 eV) PSCs. These devices also demonstrate outstanding thermostability and humidity resistance. Notably, this versatile strategy can be extended to textured perovskite/silicon tandem cells, reaching a remarkable efficiency of 28.24 % while maintaining exceptional operational stability.

Recent advancements in scalable coating methods for perovskite solar modules (PSMs) are reviewed. The report explores the fundamental aspects of scalable deposition techniques, detailing the merits and demerits of each method. It encompasses the ongoing progress in the performance and operational stability of PSMs. The review aims to offer insights into large-area perovskite coatings for stable and efficient PSMs.

The technological requirements are changing, and there is a push for more effective energy production and conversion technologies as a result of a social desire for sustainable and renewable energy sources. Solar energy conversion, particularly photovoltaic cells, offers a potentially helpful solution in this situation. Power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been reported to have increased significantly from 3% to 26.1%. The transition from laboratory PSCs to their commercialization needs scalable deposition techniques, high efficiency at a scalable level, and perovskite photovoltaic with minimal loss in PCE. In this review article, the scalable fabrication processes for perovskite solar modules (PSMs) and their fabrication challenges, as well as latest developments in PSM stability, are focused on. Finally, the future prospectus and challenges for PSMs are presented. This review will give us an overall understanding of the thin film coating inside the PSM and good insight into the future direction of development.

A hybrid intermediate layer using polymethyl methacrylate (PMMA) functionalized with ionic liquid (IL) is introduced into perovskite/C₆₀ interface where PMMA reduces nonradiative recombination loss, and the introduction of IL additionally alleviates charge accumulation at the PMMA/perovskite interface by enhancing carrier extraction. Overall, as a result of the modification, the efficiency and stability of perovskite/silicon tandem solar cells are improved simultaneously.

Abstract

Monolithic perovskite/silicon tandem solar cells have been attracted much attention in recent years. Despite their high performances, the stability issue of perovskite-based devices is recognized as one of the key challenges to realize industrial application. When comes to the perovskite top subcell, the interface between perovskite and electron transporting layers (usually C₆₀) significantly affects the device efficiency as well as the stability due to their poor adhesion. Here, different from the conventional interfacial passivation using metal fluorides, a hybrid intermediate layer is proposed—PMMA functionalized with ionic liquid (IL)—is introduced at the perovskite/C₆₀ interface. The application of PMMA essentially improves the interfacial stability due to its strong hydrophobicity, while adding IL relieves the charge accumulation between PMMA and the perovskite. Thus, an optimal wide-bandgap perovskite solar cells achieves power conversion efficiency of 20.62%. These cells are further integrated as top subcells with silicon bottom cells in a monolithic tandem structure, presenting an optimized PCE up to 27.51%. More importantly, such monolithic perovskite/silicon cells exhibit superior stability by maintaining 90% of initial efficiency after 1200 h under continuous illumination.

Publication date: March 2024

Source: Nano Energy, Volume 121

Author(s): Ming Luo, Sanlong Wang, Zhao Zhu, Biao Shi, Pengyang Wang, Guofu Hou, Qian Huang, Ying Zhao, Xiaodan Zhang

Publication date: March 2024

Source: Nano Energy, Volume 121

Author(s): Mengmeng Yuan, Hongru Ma, Qingshun Dong, Xiuyun Wang, Linghui Zhang, Yanfeng Yin, Zhehan Ying, Jingya Guo, Wenzhe Shang, Jie Zhang, Yantao Shi

Ionic coupling potassium sorbate with perovskite controls the formation of N-methyl formamidinium ions, which passivate defects and freeze halide segregation in perovskite films under intense light. Target single-junction wide-bandgap perovskite solar cells achieved a record efficiency of 22.00% with photostability of less than 2% decay over 2000 h of operation. Perovskite/TOPCon silicon tandem solar cells achieved an efficiency of 30.72%.

Abstract

Photo-induced halide segregation in wide-bandgap (WBG) perovskite leads to poor stability and limits its application in high-efficiency tandem solar cells. Here, a simple solution strategy to achieve photostable WBG perovskite solar cells (PSCs) with bandgap of ≈1.67 eV by ionic coupling potassium sorbate with defects at the buried perovskite interface is reported. Moreover, the ionic coupled potassium sorbate (ICPS) enables to control the formation of N-methyl formamidinium ions that can selectively passivate the perovskite defects at grain boundaries. As a result, the photo-induced halide segregation in the target perovskite films is frozen under intense light. The target single-junction WBG PSC achieves a record efficiency of 22.00% with an open-circuit voltage (V _OC) of 1.272 V and photostability of less than 2% decay over 2000 h of operation. Perovskite/Silicon tandem solar cells are also fabricated that achieve an efficiency of 30.72% (certified 30.09% @1.087 cm²), which is the highest efficiency reported to date with a tunneling oxide passivating contact (TOPCon) c-Si substrate. The encapsulated tandem device can maintain 97% of its initial efficiency after 1000 h of operation.

A multifunctional polymer additive PMA-AA is developed that enhances quasi-Fermi level splitting (QFLS) through bulk defect passivation and interface energy level alignment, thereby effectively increasing the open-circuit voltage (V _OC) of the perovskite solar cells (PSCs). More importantly, the efficiency of 25.04% and 21.95% is achieved with this strategy for devices and modules, respectively.

Abstract

Perovskite solar cells (PSCs) have attracted extensive attention due to their higher power conversion efficiency (PCE) and simple fabrication process. However, the open-circuit voltage (V _OC) loss remains a significant impediment to enhance device performance. Here, a facile strategy to boost the V _OC to 95.5% of the Shockley-Queisser (S-Q) limit through the introduction of a universal multifunctional polymer additive is demonstrated. This additive effectively passivates the cation and anion defects simultaneously, thereby leading to the transformation from the strong n-type to weak n-type of perovskite films. Benefitting from the energy level alignment and the suppression of bulk non-radiative recombination, the quasi-Fermi level splitting (QFLS) is enhanced.  Consequently, the champion devices with 1.59 eV-based perovskite reach the highest V _OC value of 1.24 V and a PCE of 23.86%. Furthermore, this strategy boosts the V _OC by at least 0.07 V across five different perovskite systems, a PCE of 25.04% is achieved for 1.57 eV-based PSCs, and the corresponding module (14 cm²) also obtained a high PCE of 21.95%. This work provides an effective and universal strategy to promote the V _OC approach to the detailed balance theoretical limit.

The performance of perovskite solar cells (PSCs) is enhanced through the utilization of sputtered NiO _x as a hole-transport layer. The inverted PSCs exhibit a remarkable power conversion efficiency of 20.54%, marking the highest reported performance among sputtered NiO _x -based PSCs. In the results, the adaptability of NiO _x is underscored to diverse perovskite compositions and structural variations, while maintaining stability.

Perovskite solar cells (PSCs) are now approaching their theoretical limits and the optimization of the auxiliary layers is crucial for fully exploiting the potential of perovskite materials. In this study, NiO _x as a hole-transport layer (HTL) for inverted p–i–n PSCs is focused on. Sputtered NiO _x is an attractive p-type HTL owing to its facile processing, wide energy bandgap that prevents electron transfer, high transparency, stability, and effective hole extraction. Despite substantial research on sputtered NiO _x , the relationship between the carrier concentration and work function is still unclear. In this study, the use of sputtered NiO _x as a widely compatible HTL and the effect of its thickness on PSC device performance are investigated. Inverted PSCs with the optimal 10 nm thick NiO _x achieve a remarkable power conversion efficiency of 20.54%, which is the highest reported to date for sputtered NiO _x -based PSCs. Furthermore, PSCs with various NiO _x thicknesses demonstrate similar performances, demonstrating the excellent versatility of NiO _x for use with different perovskite absorbers. The devices exhibit excellent thermal and photostability, retaining 97% of their initial power conversion efficiency at 65 °C and 1 sun illumination for 350 h. Sputtered NiO _x HTLs have great potential for use with diverse perovskite compositions and PSC structures.

In this work, ortho-, meta-, and para-isomers of phenylenediamine (PDA) spacer are introduced. Compared with p-PDA and m-PDA, o-PDA not only reduces the exciton binding energy and facilitates the effective separation of excitons, but also weakens the quantum confinement effect and realizes effective carrier transport. Importantly, 2D DJ (o-PDA)FA₃Sn₄I₁₃ solar cell shows a record power conversion efficiency of 7.18% and enhanced stability.

Abstract

2D Dion–Jacobson (DJ) tin halide perovskite shows impressive stability by introducing diamine organic spacer. However, due to the dielectric confinement and uncontrollable crystallization process, 2D DJ perovskite usually exhibits large exciton binding energy and poor film quality, resulting in unfavorable charge dissociation, carrier transport and device performance. Here, the ortho-, meta-, and para-isomers of phenylenediamine (PDA) are designed for 2D DJ tin halide perovskites. Theoretical simulation and experimental characterizations demonstrate that compared with p-PDA and m-PDA, o-PDA shows larger dipole moment, which further reduces the exciton binding energy for the 2D perovskites. Besides, there is a strong hydrogen bond interaction between o-PDA cation and inorganic octahedron, which not only improves the structural stability, but also induces larger aggregates in the precursor to form dense and uniform high-quality films, and strengthens the antioxidant barrier. More interestingly, femtosecond transient absorption further proves that o-PDA organic spacers can reduce unfavorable small n-phases, resulting in sufficient and effective charge transfer between different n-value. As a result, the 2D DJ (o-PDA)FA₃Sn₄I₁₃ solar cells achieve a record power conversion efficiency of 7.18%. The study furnishes an effective method to optimize the carrier transport and device performance by tailoring the chemical structure of organic spacers.

Single crystal is incorporated into the perovskite precursor solution and 4,6-dimethyl-2-mercaptopyrimidine is introduced to achieve a champion power conversion efficiency of 20.24% on an effective area of 1.012 cm² and a power-to-weight ratio of more than 3000 W kg⁻¹ on ultra-thin stainless-steel substrate.

Ultra-thin stainless-steel substrates with excellent water-oxygen barrier properties and high thermal and electrical conductivities are suitable for the fabrication of lightweight and flexible perovskite solar cells (FPSCs). However, the deposition of dense perovskite films on stainless steel by the solution method is crucial because short circuits caused by perovskite holes are fatal to parallel structures. Herein, a single crystal (SC) is incorporated into the precursor solution to reduce the formation of holes in perovskite films on smooth stainless-steel substrates. Additionally, a magnetic method is developed based on the properties of stainless steel to fix and fabricate FPSCs nondestructively on ultra-thin stainless-steel films with a thickness as low as 5 μm. Furthermore, 4,6-dimethyl-2-mercaptopyrimidine (DMI) was introduced to passivate the surface of the perovskite film, optimizing the contact properties of the perovskite heterojunction and adjusting the energy level of the perovskite/C₆₀ interface. Finally, ultra-thin FPSCs achieved a champion power conversion efficiency (PCE) of 20.24% on an active area of 1.012 cm² and a power-to-weight ratio over 3000 W kg⁻¹. Moreover, under continuous illumination, the stainless-steel substrates exhibited better photothermal stability than the polymer substrates. This method provides a basis for the fabrication of lightweight, low-cost, and large-area FPSCs.