Solution‐processed Small Molecular Materials: Bulk Heterojunction Organic Photovoltaic Materials, Host Materials for Phosphorescence Organic Light‐emitting Diodes, and Nondopant Thermally Activated Delayed Fluorescence Materials

Abstract

This review article surveys the recent development of small molecular materials, which are fabricated as thin films by solution process for use in optoelectronic devices. Materials with lightharvesting or electron-transporting property used in organic photovoltaics (OPVs) are the topic of the first part of this review. The second part focuses on the materials used in organic light-emitting diodes (OLEDs). There are two types of OLED materials included here: host materials for phosphorescence dopant and the recently emerging thermally activated delayed fluorescence (TADF) materials. For the TADF materials, here we focus on those that do not require the host material (and hence they are nondopant emitters) in OLEDs, and their thin film can be fabricated by the solution process. In many cases, we provide insights into the material design based on the structure-property study reported in the literature.

Highly Efficient Blue Thermally Activated Delayed Fluorescence Emitters Based on Multi-Donor Modified Oxygen-Bridged Boron Acceptor

“…Recently, thermally activated delayed fluorescence (TADF) emitters have attracted enormous attention in optoelectronic applications [1], especially for organic light-emitting diodes (OLEDs) [2][3][4][5]. For TADF, the thermally activated triplet excitons can be upconverted to singlet excited excitons by a spin-flip process named reverse intersystem crossing (RISC).…”

“…1 Φ DF , Φ PF , k p , and k d -PL efficiencies and decay rates for the prompt and delayed emissions; k ISC , k RISC , and k r -rates of intersystem crossing, reverse intersystem crossing, and radiative deactivation, respectively; k nr s -rates of nonradiative deactivation excluding (r)ISC of the singlet states.…”