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

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 light-harvesting 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.