Advances in SnO₂ for Efficient and Stable n–i–p Perovskite Solar Cells

Abstract

minimize interfacial charge accumulation and recombination. [9] In an n-i-p-structured PSC, the perovskite layer is coated on the n-type ETL, and the surface area and surface chemistry of the ETL directly affect the deposition and quality of the perovskite layer. Thus, ETL development has become one of the most important scientific subjects for developing highly efficient and stable n-i-p PSCs.To date, the commonly studied ETLs include n-type semiconducting oxides (e.g., TiO 2 , SnO 2 , ZnO, Zn 2 SnO 4 , and BaSnO 3 ) and organics (e.g., phenyl-C 61 -butyric acid methyl ester [PCBM] and C 60 ). [7,[10][11][12][13][14][15][16][17] Key properties of ETLs include the proper band energy alignment with perovskite layer, high transmittance with wide bandgap, and high conductivity. Traditionally, the compact TiO 2 / mesoporous TiO 2 stack was a key component in efficient n-i-p PSCs, owing to its well-established deposition methods and suitable optoelectronic properties. However, TiO 2 exhibits drawbackssuch as photo catalytic properties under illumination and hightemperature annealing required to achieve proper crystallinitywhich can limit PSCs for commercialization. [18] Many researchers have explored alternative candidates to replace TiO 2 , targeting simple and low-temperature fabrication processes with low cost, good reproducibility, and high chemical stability.Among various candidates, SnO 2 stands out as a promising ETL that has received significant attention in recent years, [19][20][21][22] with the best PCE of SnO 2 -based n-i-p PSCs exceeding 25%. [23] The SnO 2 ETL often exhibits several preferred features such as wide bandgap with high transmittance, good charge mobility, proper band offsets relative to common perovskites, low-temperature processable synthesis, and decent chemical stability, all of which make SnO 2 ETLs great candidates for highly efficient and stable PSCs. [24,25] In this review, we highlight the main advances in the develop ment of SnO 2 for highly efficient and stable PSCs, with a focus on the n-i-p device configuration. To help understand the research trend of SnO 2 -based PSCs, we first provide an overview of key approaches leading to record PCEs based on the development of SnO 2 deposition methods in recent years. Next, we focus on the materials chemistry associated with SnO 2 , including defects, intrinsic properties, and impact on device characteristics. We discuss the issues and challenges related to SnO 2 development and SnO 2 /perovskite interface optimization, as well as various strategies developed to address these issues in recent years. We also highlight some SnO 2 implementations related to scalable processes and flexible devices that are Perovskite solar cells (PSCs) based on the regular n-i-p device architecture have reached above 25% certified efficiency with continuously reported improvements in recent years. A key common factor for these recent breakthroughs is the development of SnO 2 as an effective electron transport layer in these devices. In this article, the key ad...

Bifunctional Passivation through Fluoride Treatment for Highly Efficient and Stable Perovskite Solar Cells

“…As reported in previous literature, a rapid degradation in the performance caused by the exposure to UV light is the main issue of TiO 2based device. [38] Due to the wider bandgap, SnO 2 absorbs less UV light and is thus more robust than TiO 2 under sunlight. However, mesoporous TiO 2 can offer more contact area and stable template for the growth of perovskite film, which may lead to better reproducibility and higher efficiency.…”

Simultaneous Chemical Crosslinking of SnO2 and Perovskite for High‐Performance Planar Perovskite Solar Cells with Minimized Lead Leakage

“…[1][2][3][4] The highest certified efficiency of perovskite solar cells (PSCs) has recently reached 25.8% since Miyasaka's group first reported the efficiency value of 3.8% in 2009. [5,6] The rapid improvement of PSCs in photoelectric conversion efficiency (PCE) is inseparable from the development of device structure, [7][8][9] the optimization of perovskite light absorption layer (PVK), [10,11] hole transport layer (HTL), [12] electron transport layer (ETL), [13] and related functional interfaces. [14] Although the efficiency of PSC is improved at an unprecedented speed, there is still room for further improvement in the light of theoretical Shockley-Queisser limit efficiency of 30.5%.…”

Recent advances in dopant-free organic hole-transporting materials for efficient, stable and low-cost perovskite solar cells

“…Conventional n–i–p architectures (including mesoporous and planar n–i–p) have been most widely used in PSCs, and the corresponding devices have given the record efficiency. 68,69 Liu's group designed a potential 4,4′-dimethoxy-triphenylamine (MeO–TPA)-based HTM (CQ2) with a conjugated π-bridge group of dibenzo[ b,d ]thiophene by using density-functional theory (DFT) in combination with Marcus theory and successfully synthesized it. 70 The CQ-2-based planar n–i–p PSCs produced a PCE of 15.2%, whereas the reference dopant-free HTM X25-based device gave a PCE of 14.3% because of its reduced J sc and FF.…”