Lead-free tin perovskite solar cells (PSCs) have emerged as a promising candidate toward high-performance and eco-friendly photovoltaic technology with great potential for future application. However, tin PSCs with over 10% efficiency usually feature an organic hole transport layer (HTL) at the illumination side that may induce device degradation during long-term operation. Removing the unstable organic HTL is an important way to solve these stability issues, but the efficiency of HTL-free tin PSCs is still much lower than that of the completed cells. Herein, it is demonstrated that formamidinium tin iodide doped with heterogeneous ammonium salts can form an upward band-bending structure to selectively extract the hole in the HTL-free devices. By using this band-bending structure, a promising efficiency of over 10% is first achieved for the lead-free PSCs with a HTL-free structure. More importantly, the optimized cell is highly stable, keeping 95% and 90% of the initial efficiency after continuous light soaking for 40 days and 80 °C annealing for 300 h, respectively. This work paves a route toward the development of efficient, eco-friendly, and highly stable perovskite photovoltaics.

中文翻译：

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具有无孔传输层结构的高效锡钙钛矿太阳能电池的界面能级管理

无铅锡钙钛矿太阳能电池（PSC）已成为高性能和环保光伏技术的有前途的候选者，具有巨大的未来应用潜力。然而，效率超过 10% 的锡 PSC 通常在照明侧具有有机空穴传输层 (HTL)，这可能会在长期运行期间导致器件退化。去除不稳定的有机 HTL 是解决这些稳定性问题的重要途径，但不含 HTL 的锡 PSC 的效率仍远低于已完成电池的效率。在此，证明了掺杂异质铵盐的甲脒锡碘化物可以形成向上的带弯曲结构，以选择性地提取无 HTL 器件中的空穴。通过使用这种带弯结构，具有无 HTL 结构的无铅 PSC 首次实现了超过 10% 的有希望的效率。更重要的是，优化后的电池高度稳定，在连续光浸泡 40 天和 80°C 退火 300 小时后分别保持初始效率的 95% 和 90%。这项工作为开发高效、环保和高度稳定的钙钛矿光伏铺平了道路。