JIALINGBO

This review breaks down the mechanisms of self-healing perovskite solar cells using polymeric additives from a bonding perspective. Functional groups such as isocyanate, disulfide, and carboxylic acid initiate the chemical interaction-based recovery of damaged perovskite devices, while hydrogen bonding and chelating groups facilitate physical interaction-based recovery. Additionally, perovskite's intrinsic properties enable mending autonomously under certain conditions.

Abstract

This review addresses the self-healing effects in perovskite solar cells (PSCs), emphasizing the significance of chemical and physical bonding as core mechanisms. Polymeric additives play a vital role in inducing self-healing phenomena along with the intrinsic properties of perovskite materials, both of which are discussed herein. As a relatively underexplored area, the self-healing effect induced by polymeric additives in PSCs is reviewed from a chemical perspective. The chemical bonds involved in self-healing include isocyanate, disulfide, and carboxylic acid groups. The physical bonds related to self-healing effects are primarily hydrogen bonding and chelation. Self-healing in flexible perovskite devices extends their lifespan and improves their mechanical robustness against environmental and mechanical stressors. This discussion delves into the initiation methods for self-healing, the conditions required, and the recovery-rate profiles. This review not only catalogs various approaches to self-healing, but also considers the fundamental limitations and potential of this phenomenon in PSCs. In addition, insights and an outlook on self-healing in perovskite-based optoelectronics are provided, offering guidance for future research and applications.

Nature Energy, Published online: 26 January 2024; doi:10.1038/s41560-024-01451-8

Compared with the conventional hole-transport layer used in inverted PSCs, hole-selective self-assembled monolayers provide multiple advantages, including conformal and uniform coating, minimized thickness, negligible optical and resistance loss, and the versatility in the interface modification.

Hole-transport layer (HTL) is of paramount importance to construct high-performance inverted perovskite solar cells (PSCs) because it not only determines the hole extraction and transport but also influences the quality of perovskite layer. Recently, self-assembled monolayers are adopted as very effective hole-selective layer to construct high-performance inverted PSCs. Compared with conventional HTL, hole-selective self-assembled monolayers (HSSAMs) offer the benefits of minimal material consumption and parasitic absorption, simple and scalable processing, and the versatility in the interface modification. Through molecule design and coating process optimization, the high-quality HSSAMs are obtained, which enable the HSSAM-based inverted PSCs to achieve greatly promoted photovoltaic performance. Herein, the progress of HSSAMs used in inverted PSCs is summarized. First, the structure characteristics of HSSAM molecules are described. Then, the effect of the structure of HSSAM molecules on their function in boosting the device performance and stability is discussed. Furthermore, the deposition strategies to form high-quality HSSAMs for inverted PSCs are analyzed. Finally, the advantages and challenges associated with application of HSSAMs in inverted PSCs are discussed, and the perspectives of the future research trends on HSSAMs for further promoting the performance of inverted PSCs are suggested.

An anion stabilization strategy is developed to simultaneously realize the excellent stability from precursor solution and films to final devices in the whole air preparation process. The influence of different anion species on the efficiency and stability of two-step deposited PSCs is comprehensively investigated and evaluated. Finally, TFSI-treated PSCs deliver an impressive efficiency of 24.16% with superior environmental and mechanical stability.

Abstract

Despite the outperforming power conversion efficiency of low-temperature and solution-processed perovskite solar cells (PSCs) realized over the past decades, the undesirable stability from precursor inks to resultant devices and harsh preparation requirements still restrain their industrial production and practical deployment. Herein, an anion stabilization strategy is developed to achieve the comprehensive durability of perovskite photovoltaics throughout the whole two-step air-processed procedure. The effect of interionic bonding strengths on the ink properties, film crystallization, and photovoltaic performances is in-depth explored and revealed. The pseudohalide bis(trifluoromethanesulfonyl)imide ions (TFSI⁻) not only improve the dispersion and stabilities of lead polyhalides and organic salt inks via strong electron-withdrawing/donating chemical sites, but also realize high composition uniformity and preferential crystal growth of subsequent deposited perovskite layers by tuning the precursor reactivity and surface absorption. Ultimately, the optimizing PSCs deliver a superior efficiency of 24.16%, accompanied by notably improved long-term stability toward extreme environmental and mechanical stimuli with lead leakage suppression. This work opens up a promising avenue toward reproducible air preparation of highly efficient, stable, and environmentally friendly perovskite optoelectronic devices via precise modulation of precursor properties.

An ionic liquid, named BMITFSI, assisted solution growth approach is proposed for fabricating high-quality perovskite single crystals with in situ self-cleaning effect, which not only gets rid of intricate post-treatments but also regulates preferential crystal facet growth, and thereby effectively ameliorates crystallographic defects for highly efficient perovskite single crystal-based photodetector application.

Abstract

Surface defects are crucial to perovskite single crystals (SCs) for versatile optoelectronic applications, whereas suffers from the intricate post-treatments and unsatisfactory reproducibility within solution growth strategy due to the residue solvent corrosion and adsorbed precursors deposition. Here, an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) is demonstrated, assisted solution growth approach for fabricating high-quality self-cleaning perovskite single crystals with no need for any post-treatment. Benefiting from the in situ assembling in crystalline surface, BMITFSI can effectively decrease the crystallographic trap density by simultaneously introducing the self-cleaning effect and optimizing the crystalline growth process. Particularly, as fabricated MAPbI₃ single crystal exhibits an impressive photodetection performance with a specific detectivity of 2.83 × 10¹² Jones in visible-IR spectrum and a sensitivity of 7.24 × 10⁴ µC Gy_air ⁻¹ cm⁻² in X-ray detection, which is as good as the conventionally fabricated crystal with elaborate post-treatments. Based on the chemical composition independent universality, this work paves an easy but efficient route to improve the current crystallization methodology toward high-quality perovskite SCs fabrication.

This work develops an ultrafast nucleation process using MACl and BACl as dual additives to 2ME without further solvent addition and the FAPbI₃ PSCs achieve a higher efficiency of 23. 6% with compact and pinhole-free morphology.

Abstract

2-Methoxyethanol (2ME), as a more environmentally friendly solvent with a lower boiling point compared to dimethylformamide, is ideal for the fabrication of perovskite solar cells (PSCs). However, when 2ME is used for antisolvent-free deposition of perovskite films, an uncontrolled nucleation process and an easy phase transition to the δ-phase often occur. Herein, an ultrafast nucleation process is developed using methylamine chloride (MACl) and n-butylammonium chloride (BACl) as dual additives in 2ME without further solvent addition. While MACl can rapidly induce MACl-based nuclei to initiate the nucleation process for formamidinium lead iodide (FAPbI₃), the addition of BACl to the precursor with MACl can further increase the nucleation rate and density of nuclei, and bypass the transition from δ- to α-phase during crystal growth to obtain a highly crystalline and pinhole-free perovskite film. As a result, the FAPbI₃ PSCs achieve a power conversion efficiency (PCE) of 23.6%. This work provides a new inspiration for controlling the crystal quality of perovskite thin films via nucleation rate suitable for upscaling.

Publication date: April 2024

Source: Nano Energy, Volume 122

Author(s): Yucheng Li, Biao Shi, Qiaojing Xu, Lingling Yan, Ningyu Ren, Yuxiang Li, Wei Han, Zhao Zhu, Yubo Zhang, Jingjing Liu, Cong Sun, Sanlong Wang, Qian Huang, Dekun Zhang, Huizhi Ren, Xiaona Du, Ying Zhao, Xiaodan Zhang

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

Metal halide perovskites (MHPs) are outstanding photovoltaic materials. Nonetheless, despite significant progress, perovskite solar cells (PSCs) still face challenges. It is crucial to adjust the crystallization process during solution crystallization and film formation to overcome this challenge. We primarily discuss the relevant aspects of MHP crystallization kinetics, systematically summarize theoretical methods, and outline modulation techniques for MHP crystallization, including solution engineering, additive engineering, and component engineering.

Abstract

Metal halide perovskites (MHPs) are considered ideal photovoltaic materials due to their variable crystal material composition and excellent photoelectric properties. However, this variability in composition leads to complex crystallization processes in the manufacturing of Metal halide perovskite (MHP) thin films, resulting in reduced crystallinity and subsequent performance loss in the final device. Thus, understanding and controlling the crystallization dynamics of perovskite materials are essential for improving the stability and performance of PSCs (Perovskite Solar Cells). To investigate the impact of crystallization characteristics on the properties of MHP films and identify corresponding modulation strategies, we primarily discuss the relevant aspects of MHP crystallization kinetics, systematically summarize theoretical methods, and outline modulation techniques for MHP crystallization, including solution engineering, additive engineering, and component engineering, which helps highlight the prospects and current challenges in perovskite crystallization kinetics

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.

Nature Energy, Published online: 18 January 2024; doi:10.1038/s41560-023-01444-z

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.

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.

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

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.