Theoretical studies on thermally activated delayed fluorescence mechanism of a series of organic light‐emitting diodes emitters comprising 2,7‐diphenylamino‐9,9‐dimethylacridine as electron donor

Abstract

According to one experimentally reported thermally activated delayed fluorescence (TADF) emitter (AcDPA-2TP), two new molecules (AcDPA-2PP and AcDPA-TPP) have been designed theoretically to probe into the effect of different acceptor strengths on their TADF mechanisms. In this work, the rates of reverse intersystem crossing (k_RISC ) of the three targeted molecules were calculated by the semiclassical Marcus rate expression. The present results demonstrate that the k_RISC rate of AcDPA-2PP is estimated to be 5.56 × 10⁶ s^-1 , about twice larger than that of AcDPA-2TP (2.63 × 10⁶ s^-1 ), and especially AcDPA-TPP is found to exhibit the largest k_RISC value (6.97 × 10⁶ s^-1 ) among the three molecules. Considering that AcDPA-2TP has been observed to be an efficient TADF emitter, our newly designed two molecules AcDPA-2PP and AcDPA-TPP are also expected to be potential TADF materials. © 2018 Wiley Periodicals, Inc.