SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 39: Organic Electronics and Photovoltaics III (joint session CPP/HL)

HL 39.9: Talk

Thursday, March 30, 2023, 11:45–12:00, GÖR 226

Utilizing charge-transfer states for narrowband and highly sensitive photodetection — •Johannes Benduhn, Louis Conrad Winkler, Awais Sawar, Jonas Kublitski, and Karl Leo — IAPP, TU Dresden, Germany

Near-infrared (NIR) spectroscopic material sensing has the potential to revolutionize many aspects of life, ranging from food control to material determination. However, currently available products are either too bulky or too expensive to be used in mobile customer applications. In this regard, organic photodetectors (ODPs) can open new perspectives due their cheap and versatile processing techniques. Nevertheless, the external quantum efficiency (EQE) as well as the specific detectivity of those devices in the NIR wavelength range are still lacking behind. In this contribution, we explore photomultiplication (PM) in fully vacuum deposited OPDs. Broadband devices achieve a maximum EQE of almost 2000 % at -10 V. Employing very sensitive measurement techniques as well as optical modelling of our devices, we are able to proof that the photomultiplication can take place even if weakly absorbing charge-transfer states are responsible for the photon harvesting. Employing a suitable donor-acceptor system as well as an optimized device architecture for photomultiplication and constructive interference in the NIR wavelength range, we achieve narrowband OPDs with the spectral response of more than 10 A W⁻¹ at a wavelength of 1100 nm with full width at half maximum even below 20 nm. These results demonstrate the versatility of OPDs and their potential for spectroscopic material sensing.