摘要
Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperatureprocessed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide(SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency(PCE) of 19.11% with an open-circuit voltage(Voc)of 1.15 V, a short-circuit current density(Jsc) of 22.77 mA cm^-2,and a fill factor(FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Vocof 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.
作为有机-无机钙钛矿杂化太阳能电池(PSCs)常用的电子传输层(ETL),氧化钛(TiO2)须在高温下烧结才能结晶,因而难以适用于柔性和串联叠层太阳能电池.本文介绍了一种低温溶液法制备TiO2/氧化锡(SnO2)电子传输层,并通过对TiO2/SnO2ETL的系统光学和电学性能测试,证明TiO2/SnO2ETL与钙钛矿层界面之间具有更好的电荷抽取能力和较少的载流子复合,这有利于光致载流子的分离和传输.因此,与单一的ETL相比,基于TiO2/SnO2的PSCs展现出更好的光伏性能,其最大光电转换效率(PCE)为19.11%,开路电压(Voc)为1.15 V,短路电流密度为22.77 mA cm^-2,填充因子为72.38%.此外,由于TiO2/SnO2电子传输层与钙钛矿层能带更匹配,电池的Voc最高达到了1.18 V.综上所述,本文提出了一种具有广泛应用前景的TiO2/SnO2电子传输层.
基金
supported by the National Key Research and Development of China (2018YFB1500103 and 2018YFB0704100)
the National Natural Science Foundation of China (61574145, 61874177, 51502315 and 61704176)
Zhejiang Provincial Natural Science Foundation (LR16F040002)
Zhejiang Energy Group (znkj-2018-118)
