Energy Materials and Surface Sciences Unit (EMSSU), Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
Adv Mater. 2019 Mar;31(11):e1804284. doi: 10.1002/adma.201804284. Epub 2019 Jan 24.
Perovskite solar cells (PSCs) have attracted great attention in the past few years due to their rapid increase in efficiency and low-cost fabrication. However, instability against thermal stress and humidity is a big issue hindering their commercialization and practical applications. Here, by combining thermally stable formamidinium-cesium-based perovskite and a moisture-resistant carbon electrode, successful fabrication of stable PSCs is reported, which maintain on average 77% of the initial value after being aged for 192 h under conditions of 85 °C and 85% relative humidity (the "double 85" aging condition) without encapsulation. However, the mismatch of energy levels at the interface between the perovskite and the carbon electrode limits charge collection and leads to poor device performance. To address this issue, a thin-layer of poly(ethylene oxide) (PEO) is introduced to achieve improved interfacial energy level alignment, which is verified by ultraviolet photoemission spectroscopy measurements. Indeed as a result, power conversion efficiency increases from 12.2% to 14.9% after suitable energy level modification by intentionally introducing a thin layer of PEO at the perovskite/carbon interface.
钙钛矿太阳能电池（PSCs）由于其高效率和低成本制造工艺，在过去几年中引起了极大的关注。然而，对热应力和湿度的不稳定性是阻碍其商业化和实际应用的一个大问题。在这里，通过结合热稳定的甲脒碘化铯基钙钛矿和耐湿的碳电极，成功地制备了稳定的钙钛矿太阳能电池，在未封装的情况下，在 85°C 和 85%相对湿度（“双 85”老化条件）下老化 192 小时后，平均保持初始值的 77%。然而，钙钛矿和碳电极之间界面的能级失配限制了电荷收集，导致器件性能不佳。为了解决这个问题，引入了一层薄薄的聚氧化乙烯（PEO），以实现改进的界面能级对准，这通过紫外光电子能谱测量得到了验证。实际上，结果表明，通过在钙钛矿/碳界面处有意引入一层薄薄的 PEO 来进行适当的能级修饰，功率转换效率从 12.2%提高到 14.9%。
