In fabrication of SnO₂ electron transfer layer (ETL) via traditional solution routes, the strong dependence of film crystallization on high temperature annealing or robust thermal treatment makes it challengeable to prepare crystallized SnO₂ ETLs at low temperature (< 150 °C). Here, we put forward a sol-gel route by which the whole fabrication process of crystallized SnO₂ ETL below 80 °C is realized for the first time. In the new route, participation of atmosphere O₂ and H₂O by refluxing is crucial as it can greatly promote Sn²⁺ oxidation and controlled hydrolysis in SnCl₂·2H₂O alcohol solution, in turn opening up an energetically favorable pathway for SnO₂ crystallization at low temperature. Systematical investigations reveal that SnO₂ ETLs have high conductivity and transmittance and appropriate energy band level, by which PSCs obtain superior photovoltaic performance, with a champion power conversion efficiency (PCE) and steady-state PCE of 19.20% and 18.48% achieved, respectively, much higher than that of the devices using high temperature annealed TiO₂ ETLs (16.61% and 15.03%). The SnO₂-ETL-based flexible PSCs also attain a high PCE up to 16.11% and among the highest records of flexible PSCs. Due to a larger band gap, SnO₂-ETLs-based PSCs show superior UV resistance against high intensity UV light irradiation.

在通过传统的溶液路线制造SnO ₂电子传输层（ETL）时，薄膜结晶对高温退火或强大的热处理的强烈依赖性使得在低温下（<150°C）制备结晶的SnO ₂ ETL具有挑战性。在这里，我们提出了一条溶胶-凝胶路线，通过该路线，首次实现了在80°C以下结晶的SnO ₂ ETL的整个制造过程。在新路线中，通过回流参与大气O ₂和H ₂ O至关重要，因为它可以大大促进SnCl ₂ ·2H _2中的Sn ²⁺氧化和受控的水解。O醇溶液又为SnO ₂在低温下结晶开辟了能量上有利的途径。系统研究表明，SnO ₂ ETL具有高电导率和透射率以及适当的能带水平，通过这些能量，PSC可获得出色的光伏性能，分别达到19.20％和18.48％的最佳功率转换效率（PCE）和稳态PCE。比使用高温退火的TiO ₂ ETL的器件要高得多（分别为16.61％和15.03％）。基于SnO ₂ -ETL的柔性PSC的PCE也高达16.11％，是柔性PSC的最高记录。由于带隙较大，SnO ₂-基于ETL的PSC对高强度紫外线照射显示出优异的抗紫外线性能。