Organic photodiodes (OPDs) with improved photo-response characteristics are reported, which are an important performance indicator. The photo response characteristics of OPDs depend on the decay rate of current due to charge carriers remaining inside the device even after interruption of the irradiated light. In this study, the effect of improving the response speed of OPDs is experimentally investigated by applying a cascade HTL to the hole-extraction interface and investigated that the introduction of multi-layered hole transport layers (HTLs) with a stepwise energy profile, called cascade shape profile, is effective in reducing the decay time of the remaining charges. For a two-layered cascade HTL OPD, the amount of remaining photo-current is minimized, equivalent to less than 70% that of single-layered HTL OPDs, when the highest-occupied-molecular-orbital (HOMO) level gaps among anode (indium tin oxide), HTL1, HTL2, and the p-type semiconductor are close to equal (Φ1 ≈ Φ2 ≈ Φ3). A cascade HTL does not negatively affect the sensitivity of OPDs, suggesting that it provides a promising means of achieving practical organic image sensors.

中文翻译：

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具有级联缓冲层的高速响应有机光电探测器

报告了具有改进的光响应特性的有机光电二极管 (OPD)，这是一个重要的性能指标。OPD 的光响应特性取决于即使在照射光中断后仍保留在器件内的电荷载流子导致的电流衰减率。在这项研究中，通过在空穴提取界面上应用级联 HTL 实验研究了提高 OPD 响应速度的效果，并研究了引入具有阶梯能量分布的多层空穴传输层 (HTL)，称为级联形状轮廓，可有效减少剩余电荷的衰减时间。对于两层级联 HTL OPD，剩余光电流量最小化，相当于单层 HTL OPD 的不到 70%，当阳极（氧化铟锡）、HTL1、HTL2 和 p 型半导体之间的最高占据分子轨道（HOMO）能级间隙接近相等时（Φ1 ≈ Φ2 ≈ Φ3）。级联 HTL 不会对 OPD 的灵敏度产生负面影响，这表明它为实现实用的有机图像传感器提供了一种有前途的方法。