Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Organic Electronics and Photovoltaics II

CPP 22.2: Talk

Tuesday, March 18, 2025, 14:15–14:30, H38

Ultrafast Response in Unbalanced Mobility Organic Photodetectors — •Felix Hergenhan, Tianyi Zhang, Karl Leo, and Johannes Benduhn — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute of Applied Physics, TU Dresden, Dresden, 01187 Germany

Organic photodetectors (OPDs) have attracted growing interest due to their potential in various optoelectronic applications. However, the slower response speed of OPDs compared to their inorganic counterparts, primarily influenced by low charge carrier mobilities, has hindered their application in high-speed technologies. In this presentation, we will discuss the dynamic behavior of OPDs, focusing on how ultrafast response times can still be achieved despite significant mobility imbalance and overall low mobility. Importantly, the role of RC (resistance-capacitance) limitations is emphasized, as they significantly impact the achievable response speed of the devices. We systematically investigated the effects of device design, device dimensions, light intensity, and applied bias on OPD performance and its dynamic behavior. Notably, special features could be identified in their dynamic response that led to improved rise and fall times of only a few nanoseconds and a cutoff frequency beyond 10 MHz. We propose a model explaining the origin of these features and demonstrate how to utilize them to achieve faster response times. By exploring the entire picture of device design, material choice, and operational conditions, we provide an outlook on the future development of ultrafast OPDs.

Keywords: organic photodetectors; ultrafast response; unbalanced mobility; overshoot