Reissig Louisa, Dalgleish Simon, Awaga Kunio
Department of Chemistry and IRCCS, Nagoya University, Furo-cho, Chikusa, 464-8602, Nagoya, Japan.
Institute of Experimental Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
Sci Rep. 2018 Oct 18;8(1):15415. doi: 10.1038/s41598-018-33822-z.
Organic photodetectors offer distinct advantages over their inorganic analogues, most notably through optical transparency and flexibility, yet their figures-of-merit still lag behind those of inorganic devices, and optimization strategies generally encounter a trade-off between device responsivity and bandwidth. Here we propose a novel photodetector architecture in which an organic photoactive semiconductor layer (S) is sandwiched between two thick insulating layers (I) that separate the semiconductor from the metallic contacts (M). In this architecture a differential photocurrent response is generated purely from the polarization of the active layer under illumination. Especially for an asymmetric MISIM design, where one insulating layer is a high-k ionic liquid I and the other a low-k polymer dielectric I, the responsivity/bandwidth trade-off is broken, since the role of the I in efficient charge separation is maintained, while the total device capacitance is reduced according to I. Thus the benefits of single insulating layer differential photodetectors (MISM) using either I or I are combined in a single device. Further improvements in device performance are also demonstrated by decreasing the series resistance of the photoactive layer through semiconductor:metal blending and by operation under strong background light.
有机光电探测器相较于其无机同类产品具有显著优势，最明显的是具备光学透明性和柔韧性，然而其品质因数仍落后于无机器件，并且优化策略通常会在器件响应度和带宽之间面临权衡。在此，我们提出一种新型光电探测器架构，其中有机光活性半导体层（S）夹在两个厚绝缘层（I）之间，这两个绝缘层将半导体与金属接触层（M）隔开。在这种架构中，差分光电流响应纯粹由光照下有源层的极化产生。特别是对于非对称MISIM设计，其中一个绝缘层是高k离子液体I，另一个是低k聚合物电介质I，响应度/带宽的权衡被打破，因为I在有效电荷分离中的作用得以维持，而根据I，器件总电容降低。因此，使用I或I的单绝缘层差分光电探测器（MISM）的优点在单个器件中得以结合。通过半导体与金属混合降低光活性层的串联电阻以及在强背景光下运行，还展示了器件性能的进一步提升。
