论文标题
三元有机太阳能电池中的能级对齐
Energy Level Alignment in Ternary Organic Solar Cells
论文作者
论文摘要
三元有机太阳能电池（TOSC）目前正在进行密集研究中，最近达到创纪录的效率为17.1％。设备开路电压（VOC）的起源已经是二进制OSC中一个多方面的问题，在TOSC中甚至更为复杂。在此，我们研究了两个供体（D）和两种受体材料（A1，A2）的三元系统，包括富勒烯和非富勒烯受体。通过改变两个受体之间的比率，我们发现VOC在两个二元系统D：A1和D：A2之间逐渐调整。为了研究这种变化的起源，我们采用了超紫色光发射光谱（UPS）深度分析，该光谱谱图用于估计三元系统中的光伏间隙。我们的结果表明，估计的光伏差距与所有混合比的VOC之间存在了极好的一致性，这表明混合成分之间的能量对齐方式因比率D：A1：A2而变化。此外，我们的结果表明，在这些三元系统中，辐射和非辐射损失的总和与混合组成无关。最后，我们证明了UPS优于X射线光发射光谱（XPS）深度分析，以解决与TOSC中常见的具有非常相似化学物质但相差的电子结构的材料组合的组成曲线。
Ternary organic solar cells (TOSC) are currently under intensive investigation, recently reaching a record efficiency of 17.1%. The origin of the device open-circuit voltage (VOC), already a multifaceted issue in binary OSC, is even more complex in TOSCs. Herein, we investigate two ternary systems with one donor (D) and two acceptor materials (A1, A2) including fullerene and non-fullerene acceptors. By varying the ratio between the two acceptors, we find the VOC to be gradually tuned between those of the two binary systems, D:A1 and D:A2. To investigate the origin of this change, we employ ultra-violet photoemission spectroscopy (UPS) depth profiling, which is used to estimate the photovoltaic gap in the ternary systems. Our results reveal an excellent agreement between the estimated photovoltaic gap and the VOC for all mixing ratios, suggesting that the energetic alignment between the blend components varies depending on the ratio D:A1:A2. Furthermore, our results indicate that the sum of radiative and non-radiative losses in these ternary systems is independent of the blend composition. Finally, we demonstrate the superiority of UPS over X-ray photoemission spectroscopy (XPS) depth profiling in resolving compositional profiles for material combinations with very similar chemical, but dissimilar electronic structures, as common in TOSCs.
