使用乙二胺四乙酸盐电解质的有机太阳能电池(OSC)的性能取决于外部偏压,推测离子是造成这种现象的原因。为了阐明电解质离子与器件的偏压依赖行为之间的详细关系,这项工作介绍了四个乙二胺四乙酸阴极中间层(EDTA-X,X=nH(4-n)Na,n=0,1,2和4)含有不同种类和数量的阳离子转化为反向OSCs。结果表明,器件初始和饱和(外部偏置处理后)功率转换效率(PCE)均随H数量的增加而降低。此外,偏置依赖程度随着H+数的增加而增加;EDTA-4H装置的PCE增量为53.4%,而EDTA-4Na装置几乎没有变化。电阻抗谱和电容-电压测试表明,界面复合被外部偏压处理大大抑制,这不是缺陷态密度降低的结果。结果表明,离子的运动,特别是H+运动,在外部电场下负责偏置相关行为,这有利于设计新的高效电解中间层,而没有偏置依赖的性能。
The performance of organic solar cells (OSCs) with edetate electrolytes depends on external bias, and ions are speculated to be responsible for this phenomenon. To clarify the detailed relationship between the ions of electrolytes and the bias-dependent behaviors of devices, this work introduces four edetate cathode interlayers (EDTA-X, X = nH(4-n)Na, n = 0, 1, 2, and 4) containing different kinds and number of cations into inverted OSCs. The results show that the devices initial and saturated (after external bias treatment) power conversion efficiencies (PCEs) both decrease with the increase in the number of H+. Moreover, the bias-dependent degrees increase with the increase in H+ number; with that, the PCE increment of EDTA-4H device is 53.4%, while that of the EDTA-4Na device is almost unchanged. The electrical impedance spectroscopy and capacitance-voltage tests reveal that the interfacial recombination is greatly suppressed by external bias treatment, which is not a result of the decreased density of defect states. The results indicate that the ion\'s motion, specifically the H+ motion, under external electrical field is responsible for the bias-dependent behavior, which is conducive to the design of new efficient electrolytic interlayers without bias-dependent performance.