Dresden 2026 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: Hybrid, Organic and Perovskite Optoelectronics and Photovoltaics IV

CPP 40.5: Talk

Wednesday, March 11, 2026, 18:00–18:15, ZEU/LICH

Wavelength-dependent charge carrier extraction of organic solar cells under operational conditions — •Lara Bartnick, Martijn Kemerink, and Clemens Göhler — IMSEAM, Heidelberg University, Germany

Organic solar cells (OSCs) have recently achieved power-conversion efficiencies of about 20%, making them increasingly promising for renewable energy applications despite still falling behind silicon photovoltaics. To understand the mechanisms that limit their performance, highly sensitive external quantum efficiency (EQE) measurements are essential, as they show how efficiently photons of different energies generate extractable charge carriers across the UV- to near-infrared spectrum.

We have measured the EQE of current standard PM6:Y6 OSCs under different initial conditions including bias voltage in both reverse and forward direction, bias illumination, and temperature, to investigate how open-circuit voltage- and fill-factor losses can be attributed to wavelength-dependent charge carrier generation efficiencies. These measurements reveal that the spectral shape of the EQE is highly sensitive to biasing conditions. By relating the voltage dependent EQE to collection fields, we have been able to identify charge carrier extraction losses under typical working conditions, which are dependent on the incident photon energy. These findings, as well as wavelength- and voltage-dependent exciton generation and recombination rates, contribute to understanding the loss mechanisms and charge extraction behaviour of OSCs.

Keywords: Organic Solar Cells; External Quantum Efficiency