Perovskite Photovoltaics Research Articles

Enhanced Perovskite Photovoltaics with Non-conjugated Polymers: Recent Developments and Future Prospects

Enhanced Perovskite Photovoltaics with Non-conjugated Polymers: Recent Developments and Future Prospects

Synergistic Redox Modulation for High-Performance Nickel Oxide-Based Inverted Perovskite Solar Modules.

Nickel oxide (NiOx)-based inverted perovskite solar cells stand as promising candidates for advancing perovskite photovoltaics towards commercialization, leveraging their remarkable stability, scalability, and cost-effectiveness. However, the interfacial redox reaction between high-valence Ni4+ and perovskite, alongside the facile conversion of iodide in perovskite into I2, significantly deteriorates the performance and reproducibility of NiOx-based perovskite photovoltaics. Here, potassium borohydride (KBH4) is introduced as a dual-action reductant, which effectively avoids the Ni4+/perovskite interface reaction and mitigates the iodide-to-I2 oxidation within perovskite film. This synergistic redox modulation significantly suppresses nonradiative recombination and increases the carrier lifetime. As a result, an impressive power conversion efficiency of 24.17% for NiOx-based perovskite solar cells is achieved, and a record efficiency of 20.2% for NiOx-based perovskite solar modules fabricated under ambient conditions. Notably, when evaluated using the ISOS-L-2 standard protocol, the module retains 94% of its initial efficiency after 2000 h of continuous illumination under maximum power point at 65°C in ambient air.

High-performance bifacial perovskite solar cells enabled by single-walled carbon nanotubes

Bifacial perovskite solar cells have shown great promise for increasing power output by capturing light from both sides. However, the suboptimal optical transmittance of back metal electrodes together with the complex fabrication process associated with front transparent conducting oxides have hindered the development of efficient bifacial PSCs. Here, we present a novel approach for bifacial perovskite devices using single-walled carbon nanotubes as both front and back electrodes. single-walled carbon nanotubes offer high transparency, conductivity, and stability, enabling bifacial PSCs with a bifaciality factor of over 98% and a power generation density of over 36%. We also fabricate flexible, all-carbon-electrode-based devices with a high power-per-weight value of 73.75 W g−1 and excellent mechanical durability. Furthermore, we show that our bifacial devices have a much lower material cost than conventional monofacial PSCs. Our work demonstrates the potential of SWCNT electrodes for efficient, stable, and low-cost bifacial perovskite photovoltaics.

Low-damage hydrogen-doped transparent electrodes towards semitransparent perovskite photovoltaics

As one kind of transparent conductive electrodes (TCEs), transparent conductive oxides (TCOs) have been widely used in perovskite solar cells (PSCs). However, the conventional magnetron sputtering usually causes high-energy particles, thus damaging the underlying functional films and deteriorating the performance of devices. Therefore, developing a low-damage method for high-quality TCO film is crucial. Here, the hydrogen and cerium co-doped indium oxide (ICO:H) films were prepared by the reactive plasma deposition (RPD) technology at room temperature. Benefiting from the hydrogen doping, the bandgap of the ICO:H film was tuned to 3.97 eV, the average transmittances reached 91.25% (from 800 nm to 1200 nm) and 81.35% (from 300 nm to 800 nm), and the carrier mobility exceeded 30 cm2/V/s. Combined with these advantages, semitransparent perovskite solar cells (ST-PSCs) without buffer layers were fabricated using ICO:H films as transparent conductive window layers, and the power conversion efficiency (PCE) was up to 17.61% (from the glass side). Furthermore, the ICO:H films were also applied in two-terminal perovskite/silicon tandem solar cells, and the PCE exceeded 25%. This low-damage method opens a new avenue for fabricating film-based optoelectronics.

Defect Passivation Refinement in Perovskite Photovoltaics: Achieving Efficiency over 45% under Low-Light and Low-Temperature Dual Extreme Conditions.

Perovskite photovoltaics have emerged as the most promising candidates for next-generation light-to-electricity technology. However, their practical application still suffers from energy loss induced by intrinsic defects within the perovskite lattice. Here, a refined defect passivation in perovskite films is designed, which shows a multi-interaction mechanism between the perovskite and passivator. Interestingly, a shift of molecular bonding is observed upon cooling down the film, leading to a stronger passivation of iodine/formamidine vacancies. Such mechanism on device under low-light and low-temperature conditions is further leveraged and a record efficiency over 45% with durable ambient stability (T90 > 4000h) is obtained. The pioneer application of perovskite solar cells in above dual extreme conditions in this work reveals the key principles of designing functional groups for the passivators, and also demonstrates the capability of perovskites for diverse terrestrial energy conversion applications in demanding environments such as polar regions and outer space.

Fabricating Solid‐Solution‐Type Perovskite/Fluoride Nanocomposites Through Sublattice Interlocking for High‐Performance Photovoltaics

AbstractAll‐inorganic α‐phase CsPbI3 perovskite with a suitable bandgap and superb optoelectronic properties is transforming the landscape of perovskite photovoltaics, but its long‐term lability associated with “soft” ionic lattice still imposes a great challenge for practical applications. Herein, a unique solid‐solution fluorination strategy is proposed to deliver an “ideal” perovskite matrix of α‐phase CsPbI3 abundant with F ions through interlocking the soft lattice of CsPbI3 with cubic‐phase CsF·3/2HF. Such a sublattice interlocking can not only stabilize the soft lattice of α‐phase CsPbI3 perovskite nanocrystals but also passivate their notorious surface defects, thereby producing a “rigid” solid‐solution‐type perovskite/fluoride CsPbI3/CsF (termed as CsPbI3:F) nanocomposite with excellent long‐term stability and a near‐unity photoluminescence efficiency. Of particular note is that these CsPbI3:F nanocomposites can work well as effective grain boundary anchors to significantly improve the photovoltaic performance of perovskite solar cells because of their F‐rich perovskite lattice, achieving a T80 stability of 1500 h under continuous maximum power point tracking and AM 1.5G illumination without the need for encapsulation. This work paves a new way to deliver perovskite materials with desirable properties for photovoltaics.

Dopant-additive synergism enhances perovskite solar modules

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies owing to their exceptional optoelectronic properties1,2. However, the lower efficiency, poor stability and reproducibility issues of large-area PSCs compared with laboratory-scale PSCs are notable drawbacks that hinder their commercialization3. Here we report a synergistic dopant-additive combination strategy using methylammonium chloride (MACl) as the dopant and a Lewis-basic ionic-liquid additive, 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl). This strategy effectively inhibits the degradation of the perovskite precursor solution (PPS), suppresses the aggregation of MACl and results in phase-homogeneous and stable perovskite films with high crystallinity and fewer defects. This approach enabled the fabrication of perovskite solar modules (PSMs) that achieved a certified efficiency of 23.30% and ultimately stabilized at 22.97% over a 27.22-cm2 aperture area, marking the highest certified PSM performance. Furthermore, the PSMs showed long-term operational stability, maintaining 94.66% of the initial efficiency after 1,000 h under continuous one-sun illumination at room temperature. The interaction between [Bcmim]Cl and MACl was extensively studied to unravel the mechanism leading to an enhancement of device properties. Our approach holds substantial promise for bridging the benchtop-to-rooftop gap and advancing the production and commercialization of large-area perovskite photovoltaics.

Materials genome engineering accelerates the research and development of organic and perovskite photovoltaics

AbstractThe emerging photovoltaic (PV) technologies, such as organic and perovskite PVs, have the characteristics of complex compositions and processing, resulting in a large multidimensional parameter space for the development and optimization of the technologies. Traditional manual methods are time‐consuming and labor‐intensive in screening and optimizing material properties. Materials genome engineering (MGE) advances an innovative approach that combines efficient experimentation, big database and artificial intelligence (AI) algorithms to accelerate materials research and development. High‐throughput (HT) research platforms perform multidimensional experimental tasks rapidly, providing a large amount of reliable and consistent data for the creation of materials databases. Therefore, the development of novel experimental methods combining HT and AI can accelerate materials design and application, which is beneficial for establishing material‐processing‐property relationships and overcoming bottlenecks in the development of emerging PV technologies. This review introduces the key technologies involved in MGE and overviews the accelerating role of MGE in the field of organic and perovskite PVs.

Dual-meniscus-assisted roller-coating for scalable and patterned perovskite solar cells

Scaling up the fabrication process for perovskite solar cells has emerged as a prominent research focus in the field of perovskite photovoltaics. Current methods for preparing large-scale perovskite solar cells often struggle to meet the simultaneous requirements of continuous production, high compatibility, and low commissioning costs necessary for industrial-scale manufacturing. Here, the roller coating method is demonstrated to realize the preparation of large-scaled and uniform perovskite films with customized patterning through a facile and stable “touch-and-roll” motion. The unique fabric-based roller and “dual-meniscus” structure guarantee accurate control of ink flow and film thickness, thereby realizing the reproducible preparation on different substrates ranging from rigid glass to flexibe polymer film. The method yielded PSCs with peak efficiencies of 14.11% (0.16 cm2) and 10.61% (1 cm2). This roller coating method exhibits a promising new avenue for advancing the scale and commercial development of perovskite photovoltaics.

Unifying Crystal Growth and Defect Passivation in Photovoltaic Perovskites: The Impact of Molecular Coordinating Strength

Unifying Crystal Growth and Defect Passivation in Photovoltaic Perovskites: The Impact of Molecular Coordinating Strength

High-Precision Tailored Polymer Molecular Weights for Specific Photovoltaic Applications through Ultrasound-Induced Simultaneous Physical and Chemical Events.

It is highly challenging to reproducibly prepare semiconducting polymers with targeted molecular weight tailored for next-generation photovoltaic applications. Once such an easily accessible methodology is established, which can not only contribute to overcome the current limitation of the statistically determined nature of semiconducting polymers, but also facilitate rapid incorporation into the broad synthetic chemists' toolbox. Here, we describe a simple yet robust ultrasonication-assisted Stille polymerization for accessing semiconducting polymers with high-precision tailored molecular weights (from low to ultrahigh molecular weight ranges) while mitigating their interbatch variations. We propose that ultrasound-induced simultaneous physical and chemical events enable precise control of the semiconducting polymers' molecular weights with high reproducibility to satisfy all the optical/electrical and morphological demands of diverse types of high-performance semiconducting polymer-based devices; as demonstrated in in-depth experimental screenings in applications of both organic and perovskite photovoltaics. We believe that this methodology provides a fast development of new and existing semiconducting polymers with the highest-level performances possible on various photovoltaic devices.

High‐Precision Tailored Polymer Molecular Weights for Specific Photovoltaic Applications through Ultrasound‐Induced Simultaneous Physical and Chemical Events

AbstractIt is highly challenging to reproducibly prepare semiconducting polymers with targeted molecular weight tailored for next‐generation photovoltaic applications. Once such an easily accessible methodology is established, which can not only contribute to overcome the current limitation of the statistically determined nature of semiconducting polymers, but also facilitate rapid incorporation into the broad synthetic chemists’ toolbox. Here, we describe a simple yet robust ultrasonication‐assisted Stille polymerization for accessing semiconducting polymers with high‐precision tailored molecular weights (from low to ultrahigh molecular weight ranges) while mitigating their interbatch variations. We propose that ultrasound‐induced simultaneous physical and chemical events enable precise control of the semiconducting polymers’ molecular weights with high reproducibility to satisfy all the optical/electrical and morphological demands of diverse types of high‐performance semiconducting polymer‐based devices; as demonstrated in in‐depth experimental screenings in applications of both organic and perovskite photovoltaics. We believe that this methodology provides a fast development of new and existing semiconducting polymers with the highest‐level performances possible on various photovoltaic devices.

Hot-Antisolvent Assisted Morphological Regulation of Perovskites for Semitransparent Photovoltaics Employing Hot-Pressing Approach

The processing of halide perovskites in the air significantly influences their morphology and surface coverage, often leading to the presence of numerous trap densities that adversely affect device performance. In this study, we explored the development of perovskite films using a solvent extraction method, where the temperature of the anisole antisolvent was varied. Our findings demonstrate that the hot-antisolvent strategy effectively controls nucleation, resulting in the formation of highly dense, pinhole-free, and crack-free perovskite films with reduced surface roughness. Films fabricated using this hot-antisolvent approach exhibited enhanced photoluminescence, indicating lower trap density and increased recombination resistance. They also showed slower charge carrier recombination rates and efficient charge extraction, suggesting the suppression of nonradiative recombination. Furthermore, the superior quality of perovskite films obtained through the hot-antisolvent strategy significantly enhanced the power conversion efficiency (PCE) of hot-pressed semitransparent perovskite solar cells. The PCE remarkably increased from 0.13% to an impressive 12.65% while maintaining an average visible transmittance of 26.55% and exceptional air stability for 2000 hours with no significant degradation in initial PCE. This study achieves a record-breaking light utilization efficiency of 3.36% in the realm of research on hot-press processes.

Close-Space Sublimation as a Scalable Method for Perovskite Solar Cells.

Vacuum techniques for perovskite photovoltaics (PV) are promising for their scalability but are rarely studied with techniques readily adaptable for industry. In this work, we study the use of close-space sublimation (CSS) for making perovskite solar cells, a technique that has seen widespread use in industry, including in PV, and benefits from high material-transfer and low working pressures. A pressed pellet of formamidinium iodide (FAI) can be used multiple times as an organic source, without needing replacement. Using CSS at a rough vacuum (10 mbar), efficient cesium formamidinium lead iodide perovskite based solar cells are obtained reaching a maximum photoconversion efficiency (PCE) of 18.7%. They maintain their performance for >650 h when thermally stressed at 85 °C in a nitrogen environment. To explain the initial rise in PCE upon heating, we used drift-diffusion simulations and identified a reduction in bulk trap density as the primary factor.

From Powder Manufacturing to Perovskite/p-type TCO Thin Film Deposition

Photovoltaic perovskites are very attractive candidates as absorber layers because of their very interesting properties. In the present work, we have two parts: first, we prepared powders of the perovskites MAPbBr3, MAPbI3, and MAPbCl3, with the aim of maximizing their purity, and then we deposited thin films using these powders previously prepared by the one-step spin-coating method. The anti-solvent used was under the same ambient deposition conditions. We concluded with a series of characterizations such as X-ray diffraction, scanning electron microscopy, and UV–visible absorption to better appreciate the quality of the films produced. The crystalline structures of the films, their surface morphology, and their optical properties from the characterizations show that we have succeeded in producing film samples suitable for photovoltaics.

Managed spatial strain uniformity for efficient perovskite photovoltaics enables minimized energy deficit

Managed spatial strain uniformity for efficient perovskite photovoltaics enables minimized energy deficit

Cost‐Effective Transparent N‐Doped Tin Oxide Electrodes with Excellent Thermal and Chemical Stabilities Enabling Stable Perovskite Photovoltaics Based on Tin Oxide Electron Transport Layer

AbstractPerovskite solar cells (PSCs) incorporating chemical‐bath‐deposited (CBD) SnO2 layers have garnered considerable attention because they combine high electron mobility and low‐temperature processing, affording remarkable photovoltaic performance. However, the acidic conditions of CBD limit its compatibility with front transparent electrodes (FTEs). Herein, cost‐effective, thermally stable, and highly transparent nitrogen‐doped SnO2 (NTO) FTEs tailored to integrate with CBD‐SnO2‐based PSCs are developed. By precisely controlling the N dopant content in the magnetron sputtering process, a NTO FTE with a sheet resistance of 38.64 Ω/square, an optical transmittance of 86.17%, a smooth surface morphology (1.2 nm), and mechanical flexibility is obtained. Furthermore, doping N in SnO2 imparts thermal and chemical stability superior to those of conventional Sn‐doped In2O3 (ITO) electrodes. Additionally, a well‐matched energy band of NTO with a SnO2 electron transport layer (ETL) and homogeneous interfaces is a critical advantage. By implementing this multifaceted strategy using a novel low‐cost NTO FTE, CBD‐SnO2‐based PSCs with elevated open‐circuit voltages and energy‐barrier‐free characteristics are fabricated. A champion power conversion efficiency of 20.43% is achieved, and 93.30% of the initial efficiency is retained even after 3 000 h without encapsulation. This integration of a NTO FTE with a SnO2 ETL paves the way for robust and long‐lasting high‐performance PSCs.

Modeling and Fundamental Dynamics of Vacuum, Gas, and Antisolvent Quenching for Scalable Perovskite Processes.

Hybrid perovskite photovoltaics (PVs) promise cost-effective fabrication with large-scale solution-based manufacturing processes as well as high power conversion efficiencies. Almost all of today's high-performance solution-processed perovskite absorber films rely on so-called quenching techniques that rapidly increase supersaturation to induce a prompt crystallization. However, to date, there are no metrics for comparing results obtained with different quenching methods. In response, the first quantitative modeling framework for gas quenching, anti-solvent quenching, and vacuum quenching is developed herein. Based on dynamic thickness measurements in a vacuum chamber, previous works on drying dynamics, and commonly known material properties, a detailed analysis of mass transfer dynamics is performed for each quenching technique. The derived models are delivered along with an open-source software framework that is modular and extensible. Thereby, a deep understanding of the impact of each process parameter on mass transfer dynamics is provided. Moreover, the supersaturation rate at critical concentration is proposed as a decisive benchmark of quenching effectiveness, yielding ≈ 10-3 - 10-1s-1 for vacuum quenching, ≈ 10-5 - 10-3s-1 for static gas quenching, ≈ 10-2 - 100s-1 for dynamic gas quenching and ≈ 102s-1 for antisolvent quenching. This benchmark fosters transferability and scalability of hybrid perovskite fabrication, transforming the "art of device making" to well-defined process engineering.

Pizza Oven Processing of Organohalide Perovskites (POPOP): A Simple, Versatile and Efficient Vapor Deposition Method

AbstractHybrid vapor deposition is one of the most appealing processes for perovskite photovoltaics fabrication, thanks to its versatile nature. By using sequentially different vapor deposition processes tailored to the inorganic and organic perovskite precursors' peculiarities, this type of process gives access to the full potential of vapor deposition. While vapor deposition of metal halides is well understood and mastered, vapor deposition of organohalide species is much more delicate (degradation of vapors, high vapor pressure, setup‐specific constraints). Here, a novel close space sublimation system is reported and in‐depth insights on the conversion into perovskite of a metal halide template are provided. In this evolution of the process, the substrate coated with metal halide template and the organohalide source are loaded together in a dedicated holder, then transferred into a vacuum chamber on a heating element already at temperature setpoint. The system enables a simple, fast, low‐cost, and easy‐to‐reproduce organohalide vapor deposition process. The formation of the perovskite in situ and identification different conversion regimes are studied. Furthermore, the influence of the chemical environment and chamber design on the process are discussed. Compositional tuning and additive engineering in the process are processed and fabricate proof of concept photovoltaic devices reaching high fill factors of 80% and 17% power conversion efficiency for a bandgap of 1.63 eV.

Anchoring Charge Selective Self-Assembled Monolayers for Tin-Lead Perovskite Solar Cells.

Self-assembled monolayers (SAMs) have displayed great potential for improving efficiency and stability in p-i-n perovskite solar cells (PSCs). The anchoring of SAMs at the conductiv metal oxide substrates and their interaction with perovskite materials must be rationally tailored to ensure efficient charge carrier extraction and improved quality of the perovskite films. Herein, SAMs molecules with different anchoring groups and spacers to control the interaction with perovskite in the p-i-n mixed Sn-Pb PSCs are selected. It is found that the monolayer with the carboxylate group exhibits appropriate interaction and has a more favorable orientation and arrangement than that of the phosphate group. This results in reduced nonradiative recombination and enhanced crystallinity. In addition, the short chain length leads to an improved energy level alignment of SAMs with perovskite, improving hole extraction. As a result, the narrow bandgap (≈1.25eV) Sn-Pb PSCs show efficiencies of up to 23.1% with an open-circuit voltage of up to 0.89V. Unencapsulated devices retain 93% of their initial efficiency after storage in N2 atmosphere for over 2500 h. Overall, this work highlights the underexplored potential of SAMs for perovskite photovoltaics and provides essential findings on the influence of their structural modification.