Research Progress of Solution-Processed Self-Host Thermally Activated Delayed Fluorescence Materials

Abstract

Over the past decade, thermally activated delayed fluorescence (TADF) materials have gained widespread attention within both the academic and industrial domains as the third-generation organic light-emitting diode (OLED) emitters. TADF molecules exhibit a small energy gap between the lowest singlet and triplet excited states (ΔEST), thereby facilitating the conversion of triplet excitons to singlet states through reverse intersystem crossing (RISC) upon thermal activation. This characteristic presents the theoretical possibility of achieving 100% exciton utilization, thereby substantially enhancing the external quantum efficiency of OLED devices. Solution processing offers several advantages, such as low cost, simple methods, high material utilization, and large-scale production, rendering it an ideal candidate for the fabrication of flexible and printable OLED devices. The host material with excellent charge transfer capabilities can effectively reduce exciton density and facilitate efficient energy transfer. Consequently, solution-processed devices constructed using self-host TADF materials can effectively balance charge carrier transport and avoid phase separation, thereby maintaining film uniformity, enhancing device performance and improving device stability. This review provides a comprehensive summary of the advancements made in the field of solution-processed self-host TADF materials. First, the basic principles and research significance of TADF materials are introduced, highlighting the potential applications of solution-processed self-host TADF materials in display and lighting devices. Subsequently, an overview of the current research progress on various classifications of solution-processed self-host TADF materials, including small molecules, dendrimers, and polymers are presented. Special emphasis is placed on elucidating the material structures and their performance within devices. Finally, a future outlook is provided regarding the development trend of self-host TADF materials, including their current deficiencies, existing issues, and potential solutions. The review aims to serve as a valuable reference for researchers in related fields, while simultaneously fostering further advancement and application of TADF materials.