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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.26: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Impact of solution processing on the photophysical properties of TADF emitters — •Konstantin Rausch, Rishabh Saxena, and Anna Köhler — Soft matter Optoelectronics, University of Bayreuth, Germany

Continuous innovation of thermally activated delayed fluorescence (TADF) compounds has led to the rapid development of these materials as emitters in efficient vacuum-deposited organic light emitting diodes (OLEDs). However, the cost of device fabrication, inefficient use of materials and limitation on pixel size are some detracting features of vacuum-deposition. An alternative cost- and materials-efficient fabrication technique is solution processing. In this regard, it is important to understand the impact of different processing conditions, such as varying solvents and host materials, on the photophysical properties of TADF emitters. In general, a donor-acceptor (D-A) strategy is adopted for the chemical design of TADF emitters. Recent studies suggest that conformational flexibility associated with the D-A dihedral angle leads to a distribution of reverse intersystem crossing rates (k_RISC); a parameter that determines the efficiency of the TADF process. In this study, we perform inverse Laplace transform fitting of emission decay, obtained using time-resolved photoluminescence measurements, to extract this distribution. Furthermore, we investigate the impact of different film-preparation methods (spin-coating and evaporation), matrix polarity and conformational rigidity of TADF emitter on the RISC rate distribution with an aim to optimize the performance of solution-processed TADF OLEDs.