High Bending Durability of Efficient Flexible Perovskite Solar Cells Using Metal Oxide Electron Transport Layer

Abstract

With a rapid progress in photovoltaic performance over the past several years, organic–inorganic perovskite solar cells (PSCs) have been regarded as a promising candidate for next-generation photovoltaic devices such as lightweight and flexible photovoltaic equipment and portable systems. However, the photovoltaic performance and its durability during the mechanical bending test of flexible PSCs (fPSCs) are insufficient for the realistic application. This inadequacy stems from a lack of a superior electron transport material (ETM) for fPSCs. Here, we describe the application of SnO2 as an ETM for fPSCs (SnO2-fPSCs), achieving outstanding photovoltaic performance and excellent mechanical bending durability. We demonstrate the high power conversion efficiency (PCE) of 17.1 and 16.2% with negligible hysteresis and the high stabilized power output of 17.0 and 15.9% of normal-architecture SnO2-fPSCs with a photoactive area of 0.1 and 1.0 cm2, respectively. Moreover, the SnO2-fPSCs exhibit an excellent bending durability that retains 76.5% of the initial PCE even after 2000 times harsh bending cycle with a small bending radius of 4.0 mm on 0.1 cm2 active area.

Recent Progress of Flexible Perovskite Solar Cells

“…The SnO 2 ETL derived at a low temperature exhibited more superior optoelectronic and semiconductor properties than the conventional TiO 2 ETL, achieving an adequate PCE of 16.11% for the resulting FPCSs. Other SnO 2 NPs were also reported for FPSC application, and PCEs of 15.21–17.1% were reported for the obtained FPSCs …”

“…Generally speaking, CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3‐ x Cl x are the most frequently studied absorbers in the early research of PSCs. But in terms of high efficiency PSCs, mixed ion perovskites such as FA x MA 1− x PbBr y I 3− y and Cs x (MA y FA 1− y ) 1− x Pb(I z Br 1− z ) 3 are more popular, partially due to their favorable band structures. Besides the tunable band gap, metal halide perovskites still have many other superior properties for solar cell applications, including excellent light harvesting, high charge carrier mobility, long carrier life time, and low cost solution deposition method.…”

“…Particularly, SnO 2 has some additional advantages such as higher optical transparency, barrier‐free energetic configuration, and better device stability . Another promising property for the SnO 2 ETL lies in the fact that efficient SnO 2 ETL can be deposited by different low temperature methods, especially the low cost solution method . For example, Ko et al prepared a Li doped SnO 2 thin film by simply spin coating SnCl 2 solution with Li‐TFSI as the additive .…”

Recent Advances of Device Components toward Efficient Flexible Perovskite Solar Cells

“…The perovskite absorber layer plays a key role in device performance. The structural formula ABX 3 provides numerous component combinations of tremendous versatility, among which organic–inorganic halide perovskites are widely used in FPSCs . Superior optoelectronic properties of the halide perovskite materials guarantee the prerequisites of achieving high‐performance FPSCs.…”

“…Yan's group used PEALD to synthesize SnO 2 ETLs followed by water vapor treatment (Figure c) and further finalized FPSCs with a PCE of 18.36% . A Japanese group realized large‐scale SnO 2 ‐based FPSC devices with a PCE of 15.9% . SnO 2 is still attracting research focus even in the PSC field .…”