Highly Efficient and Stable Perovskite Solar Cells via Modification of Energy Levels at the Perovskite/Carbon Electrode Interface
Highly Efficient and Stable Perovskite Solar Cells via Modification of Energy Levels at the Perovskite/Carbon Electrode Interface
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DOI：
10.1002/adma.201804284
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发表时间：
2019-01
影响因子：
29.4
通讯作者：
Zhifang Wu;Zonghao Liu;Zhanhao Hu;Zafer Hawash;Longbin Qiu;Yan Jiang;L. Ono;Y. Qi
中科院分区：
文献类型：
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作者：
Zhifang Wu;Zonghao Liu;Zhanhao Hu;Zafer Hawash;Longbin Qiu;Yan Jiang;L. Ono;Y. Qi
钙钛矿太阳能电池（PSC）由于其效率的快速提高和低成本的制造在过去几年中引起了极大的关注。然而，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铯基钙钛矿和耐湿碳电极，成功制备了稳定的PSC，在85℃和85％相对湿度（“双85”老化条件）的条件下老化192小时后，其平均保持初始值的77％，无需封装。然而，钙钛矿和碳电极之间界面处的能级不匹配限制了电荷收集并导致器件性能较差。为了解决这个问题，引入了聚环氧乙烷（PEO）薄层来改善界面能级排列，这一点通过紫外光电子能谱测量得到了验证。事实上，通过在钙钛矿/碳界面引入一层薄薄的 PEO，进行适当的能级修改后，功率转换效率从 12.2% 提高到 14.9%。
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.