氧化锌掺铝绒面薄膜在有机光伏电池中的应用

目前有机光伏电池的吸光活性层电学传输特性和光学吸收特性的不匹配是制约其能量转换效率提升的主要原因之一. 通过陷光结构对入射光进行调控, 提高电池对光的约束和俘获能力从而达到“电学薄”和“光学厚”的等效作用, 是解 决有机光伏电池电学和光学不匹配的有效手段. 本文采用湿法刻蚀技术获得了系列时间梯度的绒面氧化锌掺铝薄膜, 并将其作为有机光伏电池的入射陷光电极, 显著增强了电池的光学吸收. 研究发现, 当使用浓度0.5%的稀HCL腐蚀30 s后的氧化锌掺铝薄膜作为入射电极后, 电池的光电性能和效率显著增强. 基于此绒面电极电池的电流密度比平面结构的电池提高了8.17%, 效率改善了11.29%. 通过对绒面电极表面的修饰处理, 实现了电极与光活性层之间良好的界面接触, 从而减小了对电池的开路电压和填充因子的影响.

ZnO:Al textured films for improved performance in organic photovoltaics

A major issue in organic photovoltaics (OPVs) is the poor mobility and recombination of the photogenerated charge carriers. The active layer has to be kept thin to facilitate charge transport and minimize recombination losses. However, optical losses due to inefficient light absorption in the thin active layers can be considerable in OPVs. Therefore, light trapping schemes are critically important for efficient OPVs. In this paper, high efficient OPVs are demonstrated by introducing randomly nanostructured front electrodes, which are fabricated using commercially available ZnO:Al (AZO) films by means of a wet etching method. The etched AZO front electrode induces strong diffusion and scattering of the incident light, leading to the efficient light trapping within the device and enhancement of light absorption in the active layer. Such a nanostructured electrode can achieve an improved device performance by maintaining simultaneously high open-circuit voltage and fill factor values, while providing excellent short-circuit current enhancement through efficient light trapping. The best device obtained based on the textured electrode shows a 11.29% improvement in short current density and a 8.17% improvement in power conversion efficiency, as compared with the device with a flat electrode. The improvement in PCE is directly correlated with the enhancement of light absorption in the active layer due to the light scattering and trapping effect induced by the randomly nanotextured electrodes, which is confirmed by a haze factor measurement and an external quantum efficiency characterization. The well-established contact interfaces between the etched electrodes and active layers are made, and thus reduce the impact on the open-circuit voltage and fill factor values in OPVs. We thus conclude that the method of light manipulation developed in this paper will provide a promising and practical approach to fabricate high-performance and low-cost OPVs.