Photomultiplication-type organic photodetectors have emerged as a class of next generation solution-processed photodetectors with high gain. Despite this promising feature, the reported photodectors still suffer from relatively large dark currents at high bias voltages. To overcome this drawback, a mechanistic understanding of the photomultiplication effect in organic photodiodes is required. In this work, we advanced the performance of photomultiplication-type organic photodetectors by tuning the active layer composition and interfacial layers. The optimized devices exhibit small dark currents and flat dark current–voltage curves under the reverse bias condition up to −10 V. The optimized photodetectors also reached an ultra-high responsivity of 23.6 A/W and the specific detectivity of 1.04 × 1012 Jones at −10 V. More importantly, we investigated the photomultiplication process with multiple transient techniques and revealed that the photoconductive gain effect is a slow process, which relies on the photo-Schottky effect enabled by charge carrier tunneling and the accumulation of holes. Furthermore, we also demonstrated prototypical pulsed-light detection based on the optimized devices, which showed great potential for real applications.

中文翻译：

---

光电倍增型有机光电二极管的瞬态分析

光电倍增型有机光电探测器已成为一类具有高增益的下一代溶液处理光电探测器。尽管有这个有前途的特性，所报道的光电探测器在高偏置电压下仍然存在相对较大的暗电流。为了克服这个缺点，需要对有机光电二极管中的光电倍增效应有一个机制上的理解。在这项工作中，我们通过调整有源层组成和界面层来提高光电倍增型有机光电探测器的性能。优化后的器件在高达 −10 V 的反向偏压条件下表现出较小的暗电流和平坦的暗电流-电压曲线。优化后的光电探测器还达到了 23.6 A/W 的超高响应度和 1.04 × 10 的比探测率12Jones 电压为 -10 V。更重要的是，我们使用多种瞬态技术研究了光电倍增过程，发现光电导增益效应是一个缓慢的过程，它依赖于载流子隧穿和空穴积累所产生的光肖特基效应。此外，我们还展示了基于优化设备的原型脉冲光检测，显示出实际应用的巨大潜力。