Time‐Resolved Photoluminescence Lifetime Measurements of Organic Photovoltaic Materials

This research investigates organic photovoltaic (OPV) structures using time‐correlated single photon counting (TCSPC) to study time‐resolved fluorescence dynamics under low injection conditions. A picosecond laser diode with a wavelength of 650 nm and a single photon avalanche diode (SPAD) are applied for excitation and detection. The measurements are performed at an irradiance of 0.011 W/cm 2 (1.2 × 10 8 photons/pulse) which is sufficiently low to avoid damaging the sample. Decay characteristics are analyzed using iterative reconvolution. The samples include various absorber species and structural configurations, revealing fluorescence decay components as short as 30–500 ps. Such rapid dynamics can only be detected using conventional photodiode‐based setups at much higher excitation levels. The findings indicate that while absorption spectra vary with structural properties like layer thickness, decay times are primarily determined by the absorber material. TCSPC measurements thus provide deeper insights into the recombination dynamics of organic semiconductors.