Inverted structure thin-film organic solar cells (OSCs) are becoming increasingly important as they deliver higher power conversion efficiency and demonstrate better long-term stability than conventional devices. However, the energy band alignment and the built-in field across the device, which are crucial in understanding the device operation, is yet to be directly characterized. Here we present a direct visualization of the energy level alignment in operando inverted structure poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) OSCs using cross-sectional scanning Kelvin probe microscopy. The raw data of measured energy level alignment appear to be inconsistent with each other, and sometimes can even be contradictory to the device polarity observed in current density-voltage measurements. It is identified to be caused by the tip/cantilever induced convolution effect, which may severely mask abrupt energy level offsets at the thin electrode interlayers. A numerical deconvolution method is devised to quantitatively recover the energy level alignment across the device, and reveals the non-uniform electric field distribution in photoactive layer.

倒置结构的薄膜有机太阳能电池（OSC）与传统设备相比，具有更高的功率转换效率并具有更好的长期稳定性，因此变得越来越重要。然而，在理解器件操作中至关重要的能带对准和整个器件的内建场尚未得到直接表征。这里，我们现在在能级连续的直接可视化operando倒置结构聚（3-己基噻吩）（P3HT）：[6,6]-苯基-C61-丁酸甲酯（PCBM）OSC使用截面扫描开尔文探针显微镜检查。测得的能级对准的原始数据似乎彼此不一致，有时甚至可能与在电流密度-电压测量中观察到的器件极性矛盾。它被确定是由尖端/悬臂引起的卷积效应引起的，该效应可能严重掩盖薄电极夹层处的突然的能级偏移。设计了一种数字反卷积方法来定量恢复整个器件的能级对准，并揭示了光敏层中的电场分布不均匀。