Key Factors Governing the External Quantum Efficiency of Thermally Activated Delayed Fluorescence Organic Light-Emitting Devices: Evidence from Machine Learning.

Thermally activated delayed fluorescence (TADF) materials enable organic light-emitting devices (OLEDs) to exhibit high external quantum efficiency (EQE), as they can fully utilize singlets and triplets. Despite the high theoretical limit in EQE of TADF OLEDs, the reported values of EQE in the literature vary a lot. Hence, it is critical to quantify the effects of the factors on device EQE based on data-driven approaches. Herein, we use machine learning (ML) algorithms to map the relationship between the material/device structural factors and the EQE. We established the dataset from a variety of experimental reports. Four algorithms are employed, among which the neural network performs best in predicting the EQE. The root-mean-square errors are 1.96 and 3.39% for the training and test sets. Based on the correlation and the feature importance studies, key factors governing the device EQE are screened out. These results provide essential guidance for material screening and experimental device optimization of TADF OLEDs.