Wide-bandgap Perovskite Solar Cells Research Articles

Surface heterojunction based on n-type low-dimensional perovskite film for highly efficient perovskite tandem solar cells.

Enhancing the quality of junctions is crucial for optimizing carrier extraction and suppressing recombination in semiconductor devices. In recent years, metal halide perovskite has emerged as the most promising next-generation material for optoelectronic devices. However, the construction of high-quality perovskite junctions, as well as characterization and understanding of their carrier polarity and density, remains a challenge. In this study, using combined electrical and spectroscopic characterization techniques, we investigate the doping characteristics of perovskite films by remote molecules, which is corroborated by our theoretical simulations indicating Schottky defects consisting of double ions as effective charge dopants. Through a post-treatment process involving a combination of biammonium and monoammonium molecules, we create a surface layer of n-type low-dimensional perovskite. This surface layer forms a heterojunction with the underlying 3D perovskite film, resulting in a favorable doping profile that enhances carrier extraction. The fabricated device exhibits an outstanding open-circuit voltage (VOC) up to 1.34V and achieves a certified efficiency of 19.31% for single-junction wide-bandgap (1.77eV) perovskite solar cells, together with significantly enhanced operational stability, thanks to the improved separation of carriers. Furthermore, we demonstrate the potential of this wide-bandgap device by achieving a certified efficiency of 27.04% and a VOC of 2.12V in a perovskite/perovskite tandem solar cell configuration.

Surface repair of wide-bandgap perovskites for high-performance all-perovskite tandem solar cells

Wide-bandgap (WBG) perovskite solar cells (PSCs) play a fundamental role in perovskite-based tandem solar cells. However, the efficiency of WBG PSCs is limited by significant open-circuit voltage losses, which are primarily caused by surface defects. In this study, we present a novel method for modifying surfaces using the multifunctional S-ethylisothiourea hydrobromide (SEBr), which can passivate both Pb-I and FA-I terminated surfaces. Moreover, the SEBr upshifted the Fermi level at the perovskite interface, thereby promoting carrier collection. This proposed method was effective for both 1.67 and 1.77 eV WBG PSCs, achieving power conversion efficiencies (PCEs) of 22.47% and 19.90%, respectively, with VOC values of 1.28 and 1.33 V, along with improved film and device stability. With this advancement, we were able to fabricate monolithic all-perovskite tandem solar cells with a champion PCE of 27.10%. This research offers valuable insights for passivating the surface trap states of WBG perovskite through rational multifunctional molecular engineering.

Multifunctional Surface Treatment against Imperfections and Halide Segregation in Wide-Band Gap Perovskite Solar Cells.

Mixed-halide wide-band gap perovskites (WBPs) still suffer from losses due to imperfections within the absorber and the segregation of halide ions under external stimuli. Herein, we design a multifunctional passivator (MFP) by mixing bromide salt, formamidinium bromide (FABr) with a p-type self-assembled monolayer (SAM) to target the nonradiative recombination pathways. Photoluminescence measurement shows considerable suppression of nonradiative recombination rates after treatment with FABr. However, WBPs still remained susceptible to halide segregation for which the addition of 25% p-type SAM was effective to decelerate segregation. It is observed that FABr can act as a passivating agent of the donor impurities, shifting the Fermi-level (Ef) toward the mid-band gap, while p-type SAM could cause an overweight of Ef toward the valence band. Favorable band bending at the interface could prevent the funneling of carriers toward I-rich clusters. Instead, charge carriers funnel toward an integrated SAM, preventing the accumulation of polaron-induced strain on the lattice. Consequently, n-i-p structured devices with an optimal MFP treatment show an average open-circuit voltage (VOC) increase of about 20 mV and fill factor (FF) increase by 4% compared with the control samples. The unencapsulated devices retained 95% of their initial performance when stored at room temperature under 40% relative humidity for 2800 h.

Correction to Bication Thiocyanate Salts for Advanced Performance of Wide-Band Gap Perovskite Solar Cells

Correction to Bication Thiocyanate Salts for Advanced Performance of Wide-Band Gap Perovskite Solar Cells

Hydrophobic Hydrogen-Bonded Polymer Network for Efficient and Stable Perovskite/Si Tandem Solar Cells.

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 (Voc ) and fill factor. As a result, the optimized single-junction WBG PSC achieves an impressive efficiency of 23.18 %, with Voc 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.

High performance wide bandgap perovskite solar cell with low VOC deficit less than 0.4 V

Wide bandgap perovskite solar cells (PSCs) have attracted significant attention because they can be applied to the top cells of tandem solar cells. However, high open-circuit voltage (VOC) deficit (>0.4 V) result from poor crystallization and high non-radiative recombination losses become a serious limitation in the pursuit of high performance. Here, the relevance between different PbI2 proportions and performance parameters are revealed through analysis of surface morphology, residual stress, and photostability. The increase of PbI2 proportion promotes crystal growth and reduces the work function of the perovskite film surface and promotes the energy level alignment with the carrier transport layer, which decreased the VOC deficit. However, residual PbI2 exacerbated the stress level of perovskite film, and the resulting lattice disorder deteriorated the photostability of the device. Ultimately, after the synergistic passivation of residual PbI2 and PEAI, the VOC achieves 1.266 V and VOC deficit is less than 0.4 V, the record value in wide bandgap PSCs.

Unraveling the relationship between the phenethylammonium-induced 2D phase on the perovskite surface and inverted wide bandgap perovskite solar cell performance

We studied the impact of phenethylammonium chloride on PIN-structured wide bandgap perovskite solar cells. Elimination of the 2D phase results in a champion efficiency of 20.61% and a VOC loss of only 410 mV with hysteresis-free J–V curves.

Selective reactivity-assisted sacrificial additive coating for surface passivation of wide bandgap perovskite solar cells with cesium tetrafluoroborate

A novel method, named “selective reactivity-assisted sacrificial additive coating”, allowed the BF4− from the sacrificial additive to react selectively with the Cs+ from the perovskite, forming CsBF4 to passivate the A-site vacancy on the surface.

Host–Guest Complexation in Wide Bandgap Perovskite Solar Cells

Host–Guest Complexation in Wide Bandgap Perovskite Solar Cells

Opportunities and challenges in perovskite-organic thin-film tandem solar cells.

Efficiency is paramount in enhancing the performance and cost-effectiveness of solar cells. Recent advancements in single-junction perovskite solar cells (PSCs) have yielded an impressive efficiency of 26.1%, nearing their theoretical limit. Meanwhile, multi-junction tandem solar cells exhibit a remarkable efficiency potential exceeding 42%, surpassing the 33% limit of single-junction cells, thereby opening avenues for ultra-high-efficiency solar cells. Tandem solar cells (TSCs) represent a groundbreaking photovoltaic technology, offering high efficiency, low cost, and a simple fabrication process. Among various TSCs, perovskite-organic TSCs (PO TSCs) are particularly promising due to their ability to leverage the complementary strengths of PSCs and organic solar cells (OSCs). PO TSCs are poised to outperform existing TSCs in terms of device performance, manufacturing cost, and diverse applications. The introduction of Y6-series non-fullerene acceptors (NFAs) over the past three years has significantly advanced the development of OSCs, leading to remarkable progress in PO TSCs. This paper commences by elucidating the advantages and potential of OSCs as bottom sub-cells in PO TSCs, followed by an in-depth review of mainstream interconnection layer (ICL) design. It then addresses key challenges in wide bandgap PSCs, including phase segregation, photovoltage loss, energy loss, and long-term stability. The paper concludes by examining critical factors influencing the future development of PO TSCs.

Defect passivation engineering of wide-bandgap perovskites for high-performance solar cells

This article provides a comprehensive review of the strategies for passivating defects in wide-bandgap perovskite solar cells.

Molecular engineering with CuanCl for effective optimization of a defective interface for wide-bandgap perovskite solar cells

Molecular engineering with CuanCl forms a coordination bond with under-coordinated Pb2+ and an ionic bond with negatively charged defects, resulting in effcient defect reduction for stable wide-bandgap perovskite solar cells.

Preparation of wide-bandgap perovskite thin films by propylamine hydrochloride assisted gas quenching method

Perovskite is a material with excellent photovoltaic properties, and the efficiency of perovskite solar cells has increased rapidly in recent years. By utilizing the adjustable bandgap characteristics of perovskite materials, wide-bandgap perovskite solar cells can be combined with narrow-bandgap solar cells to make tandem solar cells. Tandem devices can improve the utilization of the solar spectra and achieve higher power conversion efficiency. An important prerequisite for preparing efficient photovoltaic devices is to fabricate high-quality perovskite active layers. Antisolvent-assisted spin-coating is currently a commonly used method for preparing high-quality perovskite films in the laboratory. However, the low solubility of inorganic cesium and bromine salts in the preparation of wide-bandgap perovskite thin films leads to a fast crystallization rate, poor crystallization quality and a large number of defects, seriously reducing the photovoltaic performance of the devices. In addition, the antisolvent has a narrow working window, which is not conducive to the preparation of large-area perovskite films. In this work, a mild gas quenching process is used to assist the spin-coating method in preparing wide-bandgap perovskite films, and propylamine hydrochloride is introduced as an additive to improve the crystallization quality and uniformity of large-area preparation of perovskite film. The interaction between the propylamine cation and the perovskite component produces a two-dimensional perovskite phase. Two-dimensional phase is used as the growth template for perovskite composition in order to reduce the formation energy of <i>α</i>-phase perovskite, which is beneficial to uniform nucleation and preferential orientation growth of perovskite, the increase of grain size and the decrease of grain boundaries within the film. The improvement of the crystalline quality of the perovskite film can reduce the defect density inside the film and suppress the non-radiative recombination of the photogenerated carriers. The perovskite solar cell with a bandgap of 1.68 eV, prepared by using this strategy, achieves a power conversion efficiency of 21.48%. In addition, the 8 cm×8 cm wide-bandgap perovskite films prepared by this method exhibit good uniformity. This work provides a strategy for developing the process of efficient and large-area perovskite photovoltaic devices.

Interfacial modification engineering for efficient and stable MA-free wide-bandgap perovskite solar cells by grain regrowth

Introducing GuSCN reduces the defect density of perovskites by one order of magnitude. Consequently, an MA-free opaque wide-bandgap perovskite solar cell achieves 20.92% power conversion efficiency with excellent stability.

Custom-tailored solvent engineering for efficient wide-bandgap perovskite solar cells with a wide processing window and low VOC losses

A DMPU custom-tailored solvent system effectively improved the film quality of perovskites, achieving one of the highest VOC of 1.256 V for 1.65 eV wide-bandgap PSCs.

Crystallization control of wide-bandgap perovskites for efficient solar cells via adding an anti-solvent into the perovskite precursor.

Organic-inorganic halide-based wide-bandgap perovskite solar cells (PSCs) have been researched extensively due to their potential application in tandem solar cells. In this study, we directly added an anti-solvent (diethyl ether, DE) into the perovskite precursor for controlling the crystallization process of perovskite layers with a wide bandgap (1.74 eV). The introduction of DE could facilitate the nucleation and accelerate the perovskite growth during the spin-coating process. Due to the improved crystallization of the perovskite, the wide-bandgap PSCs showed a high power-conversion efficiency (PCE) of 19.7% on average with improved current density and fill factor. In contrast, the control devices without using DE exhibited a low average PCE of 17.6%. Moreover, the ambient stability of the related PSCs was simultaneously enhanced with a remarkably decreased PCE degradation, from 31.3% to 16.8%, after 16 days of storage and measurement. The DE-assisted well-crystallized PSCs showed a highest PCE of 20.1%, with a stable current output and negligible hysteresis. Our research provides a simple and effective way for controlling the crystallization of wide-bandgap perovskite layers and hence improving the performance of wide-bandgap PSCs.

Achieving a high open-circuit voltage of 1.339 V in 1.77 eV wide-bandgap perovskite solar cells via self-assembled monolayers

A self-assembled monolayer of DCB-BPA hole-selective layer facilitates the improved buried-interface quality, leading to a certified VOC of 1.339 V of 1.77 eV wide-bandgap perovskite solar cells.

Enhanced charge transport of wide-bandgap perovskite solar cells enabled by crown ether-mediated crystal modulation

Benzo-18-crown-6-ether was employed to regulate the crystallization of wide-bandgap perovskites, inducing the increased crystallinity and favorable crystal orientation, resulting in improved performance and stability of the corresponding devices.

Freezing Halide Segregation Under Intense Light for Photostable Perovskite/Silicon Tandem Solar Cells

AbstractPhoto‐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 (VOC) 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.

Rationalizing Performance Losses of Wide Bandgap Perovskite Solar Cells Evident in Data from the Perovskite Database

AbstractMetal halide perovskites (MHPs) have become a widely studied class of semiconductors for various optoelectronic devices. The possibility to tune their bandgap (Eg) 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 Eg tuning in wide Eg MHP semiconductors. Recent literature on wide Eg 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 Eg MHP absorbers, and 3) dynamically evolving compositional heterogeneity due to light‐induced phase segregation phenomena.