SKM 2023 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 39: Organic Electronics and Photovoltaics III (joint session CPP/HL)
HL 39.1: Vortrag
Donnerstag, 30. März 2023, 09:30–09:45, GÖR 226
Determining exciton diffusion lengths in organic non-fullerene acceptors with Kinetic Monte Carlo Simulation — •Wenchao Yang, Safakath Karuthedath, Catherine Castro, Julien Gorenflot, and Frederic Laquai — KAUST Solar Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
Optimal exciton diffusion length (LD) is a key parameter for reducing losses during exciton to charge carrier conversion in organic solar cells (OSC). However, different research groups report contradicting numbers for the same non-fullerene acceptors (NFA) using different lifetimes to calculate LD. In this work, in order to verify the measured LD’s in NFAs (ITIC, IT4F, ITM and IT2Cl) using transient absorption (TA) spectroscopy, we employed the Kinetic Monte Carlo (KMC) method to simulate the exciton dynamics and calculate the corresponding LD. With the assumption of Forster resonant energy transfer type exciton hopping rate in a cubic lattice, the TA decay kinetics under different fluences are reproduced by the KMC simulation, and the only free parameter: the energetic disorder σ is extracted. The use of the lifetime τ measured by time-resolved photoluminescence in neat NFA enables to reproduce the transients using more realistic σ values. The LD’s in the NFAs are further calculated with the τ’s and found to be consistent with the experimental values. This work provides microscopic descriptions of exciton diffusion and more insight into the determination of LD in organic semiconductors.