Kim Myeong In, Lee Soonyong, Kang Jinhyeon, Kim Jaehyeong, Wu Ziang, Won Jong Ho, Baek Seyeon, Chung Dae Sung, Kim Jin Young, Jung In Hwan, Woo Han Young
Department of Organic and Nano Engineering and Human-Tech Convergence Program, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.
Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.
Adv Mater. 2024 Sep;36(36):e2404597. doi: 10.1002/adma.202404597. Epub 2024 Jul 23.
Photomultiplication (PM)-type organic photodetectors (OPDs), which typically form a homogeneous distribution (HD) of n-type dopants in a p-type polymer host (HD PM-type OPDs), have achieved a breakthrough in device responsivity by surpassing a theoretical limit of external quantum efficiency (EQE). However, they face limitations in higher dark current and slower dynamic characteristics compared to p-n heterojunction (p-n HJ) OPDs due to inherent long lifetime of trapped electrons. To overcome this, a new PM-type OPD is developed that demonstrates ultrafast dynamic properties through a vertical phase separation (VPS) strategy between the p-type polymer and n-type acceptor, referred to as VPS PM-type OPDs. Notably, VPS PM-type OPDs show three orders of magnitude increase in -3 dB cut-off frequency (120 kHz) and over a 200-fold faster response time (rising time = 4.8 µs, falling time = 8.3 µs) compared to HD PM-type OPDs, while maintaining high EQE of 1121% and specific detectivity of 2.53 × 10 Jones at -10 V. The VPS PM-type OPD represents a groundbreaking advancement by demonstrating the coexistence of p-n HJ and PM modes within a single photoactive layer for the first time. This innovative approach holds the potential to enhance both static and dynamic properties of OPDs.
光电倍增（PM）型有机光电探测器（OPD）通常在p型聚合物主体中形成n型掺杂剂的均匀分布（HD）（HD PM型OPD），通过突破外部量子效率（EQE）的理论极限，在器件响应度方面取得了突破。然而，由于俘获电子固有的长寿命，与p-n异质结（p-n HJ）OPD相比，它们在更高的暗电流和较慢的动态特性方面面临限制。为了克服这一问题，开发了一种新型PM型OPD，它通过p型聚合物和n型受体之间的垂直相分离（VPS）策略展示了超快动态特性，称为VPS PM型OPD。值得注意的是，与HD PM型OPD相比，VPS PM型OPD的-3 dB截止频率提高了三个数量级（120 kHz），响应时间快了200多倍（上升时间 = 4.8 µs，下降时间 = 8.3 µs），同时在-10 V时保持1121%的高EQE和2.53×10琼斯的比探测率。VPS PM型OPD首次在单个光活性层内展示了p-n HJ和PM模式的共存，代表了一项开创性的进展。这种创新方法有可能提高OPD的静态和动态特性。
