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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Hybrid, Organic and Perovskite Optoelectronics and Photovoltaics II

CPP 25.5: Vortrag

Dienstag, 10. März 2026, 12:30–12:45, ZEU/0260

Enhancing device performance parameters of organic photodiodes by understanding the thickness dependence of the reverse dark current — •Fred Kretschmer¹, Tianyi Zhang¹, Oskar J. Sandberg², Mathias Nyman², Karl Leo¹, and Johannes Benduhn¹ — ¹Institute of Applied Physics, TU Dresden, Dresden, Germany — ²Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland

In recent years, organic photodetectors (OPDs) have attracted interest due to their advantageous properties and rapidly advancing performance, making them promising not only as complements to inorganic photodetectors but also for emerging applications in bioimaging, health monitoring, and high-speed optoelectronics. A key figure of merit for comparing PDs is the specific detectivity (D^*), which quantifies the detector’s ability to sense weak optical signals. Achieving high D^* relies on maximizing charge carrier extraction while minimizing internal noise. Under reverse bias, OPD performance is particularly influenced by shot noise, which is proportional to the dark current (J_D).

In this work, the variation of J_D with active-layer thickness across multiple energy-gap-tuned bulk-heterojunction systems was examined. Surprisingly, the dark current exhibits a thickness-dependent minimum, contrary to the general assumption that J_D only decreases with thickness. Using sensitive, temperature-dependent current-voltage measurements together with drift-diffusion simulations, the new minimum feature was confirmed, and improvements in the specific detectivity of OPDs were achieved.

Keywords: Organic Photodetector; Dark current; Detectivity; Drift-Diffusion-Simulation