In Sn-based halide perovskite solar cells (PSCs), the oxidation of Sn²⁺ to Sn⁴⁺ under ambient air leads to unwanted p-type doping in the perovskite film, which is a main reason for increased background carrier density and low efficiency. Here, we find that the introduction of bromide into formamidinium tin iodide (CH(NH₂)₂SnI₃, FASnI₃) lattice significantly lowers the carrier density of perovskite absorber, which is thought to be a result of reduction of Sn vacancies. It reduces the leakage current of devices, increases recombination lifetime, and finally improves open-circuit voltage and fill factor of the resulting devices employing mesoporous TiO₂ as an electron transport layer. Consequently, a high power conversion efficiency (PCE) of 5.5% is achieved with an average PCE of 5%, and after encapsulation the devices are highly stable over 1000 h under continuous one sun illumination including the ultraviolet region. This study suggests a simple approach for improving stability and efficiency in FASnI₃-based PSCs.

中文翻译：

---

降低甲酰胺锡钙钛矿中载流子的密度及其对钙钛矿太阳能电池稳定性和效率的有益影响

在基于Sn的卤化物钙钛矿太阳能电池（PSC）中，在环境空气下Sn ²⁺氧化为Sn ⁴⁺会导致钙钛矿薄膜中出现有害的p型掺杂，这是增加背景载流子密度和降低效率的主要原因。在这里，我们发现将溴化物引入到碘化锡（CH（NH ₂）₂ SnI ₃，FASnI ₃）晶格中会显着降低钙钛矿吸收体的载流子密度，这被认为是锡空位降低的结果。它减少了器件的泄漏电流，延长了复合寿命，并最终改善了采用介孔TiO _2的器件的开路电压和填充系数作为电子传输层。因此，在平均PCE为5％的情况下，可实现5.5％的高功率转换效率（PCE），并且封装后，该器件在连续一个阳光照射下（包括紫外线区域）在1000小时内保持高度稳定性。这项研究提出了一种简单的方法来提高基于FASnI ₃的PSC的稳定性和效率。