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The design of high-quality junctions capable of efficiently extracting carriers from perovskite-based absorbers is key in the transition from lab-scale devices to modules. In the so-called n–i–p configuration, SnO2 nanoparticle (np-SnO2) films have been thoroughly investigated as electron transporting layers (ETLs) in view of their good optimal band alignment, chemical stability and appropriate surface chemistry for nucleating high-quality perovskite films. In this report, we show for the first time that np-SnO2 films are characterized by a heterogeneous surface electronic landscape and introducing quasi-monoenergetic conformal layers between the transparent conducting oxide (TCO) and the np-SnO2 film can lead to significant improvement in perovskite solar modules. These SnOx extraction layers are developed using a highly innovative plasma-modified atomic layer deposition (PMALD) tool, which enables tuning the Sn : O ratio, conductivity, and effective work function. Energy-filtered photoemission electron microscopy (EF-PEEM) shows a remarkably homogeneous surface electronic landscape of PMALD SnOx. We examine the impact of PMALD-SnOx in an n–i–p device configuration, with poly(triarylamine) (PTAA) as the hole transporting layer, which leads to the improvement in perovskite module power conversion efficiency from 17.9% to 20.1%, with an active area of 23.2 cm2. Furthermore, the devices retained 92% of their initial efficiency for 2700 h at 85 °C and 85% relative humidity and 96% for 1000 h under continuous illumination with maximum power point tracking. [ABSTRACT FROM AUTHOR]

We integrated transparent antireflective coatings and transparent electrodes onto flexible colorless polyimide (CPI) substrates to fabricate high-performance flexible perovskite solar cells. Multifunctional PPFC/CPI/IGTO substrates were fabricated by sputtering the optimal plasma-polymerized fluorocarbon (PPFC) antireflective coating and InGaTiO (IGTO) electrode films on both sides of the CPI substrate. By applying PPFC with a low refractive index (1.38) as an antireflective coating, the transparency of the PPFC/CPI/IGTO substrate increased by an additional 1.2%. In addition, owing to the amorphous characteristics of the PPFC and IGTO layers, the PPFC/CPI/IGTO substrate showed constant sheet resistance and transmittance change even after 10,000 cycles during the bending tests. The flexible perovskite solar cells, fabricated on the PPFC/CPI/IGTO substrate, exhibited an increase in current density of 1.48 mA/cm2 after the deposition of the PPFC antireflective coating. These results confirmed that the PPFC/CPI/IGTO substrate was durable against high-temperature treatment, flexible, and exhibited excellent electrical characteristics. This enhanced the efficiency and durability of the flexible perovskite solar cells. Moreover, the hydrophobic PPFC layer allowed the self-cleaning of inflexible perovskite solar cells. Given these attributes, the PPFC/CPI/IGTO structure has been recognized as a good choice for multifunctional substrates of flexible perovskite solar cells, presenting the potential for enhancing performance. IMPACT STATEMENT: We have confirmed the durability of PPFC/CPI/IGTO substrates against high-temperature treatment, their flexibility, transparency, and their exceptional electrical properties, suggesting them as a prime selection for FPSCs. [ABSTRACT FROM AUTHOR]

Author(s): Jason J. Yoo [sup.1] [sup.8] , Gabkyung Seo [sup.2] [sup.7] , Matthew R. Chua [sup.3] , Tae Gwan Park [sup.4] , Yongli Lu [sup.1] , Fabian Rotermund [sup.4] , [...], Metal halide perovskite solar cells (PSCs) are an emerging photovoltaic technology with the potential to disrupt the mature silicon solar cell market. Great improvements in device performance over the past few years, thanks to the development of fabrication protocols.sup.1-3, chemical compositions.sup.4,5 and phase stabilization methods.sup.6-10, have made PSCs one of the most efficient and low-cost solution-processable photovoltaic technologies. However, the light-harvesting performance of these devices is still limited by excessive charge carrier recombination. Despite much effort, the performance of the best-performing PSCs is capped by relatively low fill factors and high open-circuit voltage deficits (the radiative open-circuit voltage limit minus the high open-circuit voltage).sup.11. Improvements in charge carrier management, which is closely tied to the fill factor and the open-circuit voltage, thus provide a path towards increasing the device performance of PSCs, and reaching their theoretical efficiency limit.sup.12. Here we report a holistic approach to improving the performance of PSCs through enhanced charge carrier management. First, we develop an electron transport layer with an ideal film coverage, thickness and composition by tuning the chemical bath deposition of tin dioxide (SnO.sub.2). Second, we decouple the passivation strategy between the bulk and the interface, leading to improved properties, while minimizing the bandgap penalty. In forward bias, our devices exhibit an electroluminescence external quantum efficiency of up to 17.2 per cent and an electroluminescence energy conversion efficiency of up to 21.6 per cent. As solar cells, they achieve a certified power conversion efficiency of 25.2 per cent, corresponding to 80.5 per cent of the thermodynamic limit of its bandgap. An improved device design for perovskite-based photovoltaic cells enables a certified power conversion efficiency of 25.2 per cent, translating to 80.5 per cent of the thermodynamic limit for its bandgap, which approaches those achieved by silicon solar cells.

Developing non‐halogenated solvent‐processed organic solar cells (OSCs) demands precise control over the bulk‐heterojunction (BHJ) morphology of the photoactive layer. However, the limited solubility of halogen‐free solvents to photoactive materials hinders microstructure morphology fine‐tuning for boosting photovoltaic performance. This study not only examines the debated intermolecular interactions between the DBrDIB solid additive and photoactive materials but also analyzes the substantial influence of volatile solid additive on the BHJ morphological properties. The DBrDIB effectively restricts the excessive aggregation of Y6‐BO and regulates the phase separation, which is attributed to strong intermolecular interactions with Y6‐BO and rapid quenching during morphology formation. It then achieves a well‐mixed D/A phase with favorable domain size, resulting in a balanced aggregation and dispersion of D/A, ultimately leading to markedly enhanced charge transfer and transport as well as suppressed charge recombination. The transformative use of the o‐xylene/DBrDIB solvent system propels PM6:Y6‐BO and PM6:Y6‐HU OSCs to impressive efficiencies of 17.9% and 19.1%, respectively, outperforming those of the control devices. These findings provide crucial insights into theoretical and experimental areas, offering actionable guidelines for designing high‐performance OSCs processed from halogen‐free solvent. [ABSTRACT FROM AUTHOR]

Author(s): Eui Hyuk Jung [sup.1] , Nam Joong Jeon [sup.1] , Eun Young Park [sup.1] , Chan Su Moon [sup.1] [sup.2] , Tae Joo Shin [sup.3] , Tae-Youl Yang [sup.1] [...], Perovskite solar cells typically comprise electron- and hole-transport materials deposited on each side of a perovskite active layer. So far, only two organic hole-transport materials have led to state-of-the-art performance in these solar cells.sup.1: poly(triarylamine) (PTAA).sup.2-5 and 2,2E,7,7E-tetrakis(N,N-di-p-methoxyphenylamine)-9,9E-spirobifluorene (spiro-OMeTAD).sup.6,7. However, these materials have several drawbacks in terms of commercialization, including high cost.sup.8, the need for hygroscopic dopants that trigger degradation of the perovskite layer.sup.9 and limitations in their deposition processes.sup.10. Poly(3-hexylthiophene) (P3HT) is an alternative hole-transport material with excellent optoelectronic properties.sup.11-13, low cost.sup.8,14 and ease of fabrication.sup.15-18, but so far the efficiencies of perovskite solar cells using P3HT have reached only around 16 per cent.sup.19. Here we propose a device architecture for highly efficient perovskite solar cells that use P3HT as a hole-transport material without any dopants. A thin layer of wide-bandgap halide perovskite is formed on top of the narrow-bandgap light-absorbing layer by an in situ reaction of n-hexyl trimethyl ammonium bromide on the perovskite surface. Our device has a certified power conversion efficiency of 22.7 per cent with hysteresis of [plus or minus]0.51 per cent; exhibits good stability at 85 per cent relative humidity without encapsulation; and upon encapsulation demonstrates long-term operational stability for 1,370 hours under 1-Sun illumination at room temperature, maintaining 95 per cent of the initial efficiency. We extend our platform to large-area modules (24.97 square centimetres)--which are fabricated using a scalable bar-coating method for the deposition of P3HT--and achieve a power conversion efficiency of 16.0 per cent. Realizing the potential of P3HT as a hole-transport material by using a wide-bandgap halide could be a valuable direction for perovskite solar-cell research. A double-layered halide architecture for perovskite solar cells enables the use of dopant-free poly(3-hexylthiophene) as a hole-transport material, forming stable and scalable devices with a certified power conversion efficiency of 22.7 per cent.

Long‐chain organic halide salts are widely used in perovskite‐based optoelectronic devices for surface passivation owing to their capability to interact with the surface defects of perovskites. Here, aluminum oxide (AlOx) is introduced via atomic layer deposition onto octylammonium iodide (OAI) to exploit the benefits of organic halide salts without generating undesired defects. The devices incorporating AlOx on OAI‐treated perovskite (OAI/AlOx) show enhancement in both device performance and photo‐stability compared to those with only treatment. A diffusion of aluminum from AlOx into the perovskite through surface characterization contributes to a uniform photo‐generated carrier transport in both the surface and the bulk of the perovskite absorber. In addition, it is revealed that light‐induced two‐dimensional perovskite formation on OAI/AlOx. This may be ascribed to preventing the loss of OA cations due to the presence of AlOx, leading to a decrease in the number of iodine anions which suppresses the light‐induced degradation of corresponding devices. Consequently, the devices show over 24% efficiency and retain their efficiency over 1000 hours under continuous light illumination. [ABSTRACT FROM AUTHOR]