Soft electronic materials such as organic semiconductors have attracted a huge interest for display, sustainable energy and healthcare applications. These applications include organic light-emitting diodes (OLED), photovoltaics (OPV), photodetectors (OPD), electrochemical transistors (OECT) and solar fuel devices. One of the key challenges for the development of these devices is a fundamental understanding of the organic semiconductor thin films in terms of their structure-property relationship. Although promising, there is still a lack of clear understanding of the impact of molecular structures on photophysical and electrochemical processes, and device structures on interfacial energetics and properties, which are critical for high-performance organic optoelectronic devices.

In this talk, I will introduce our recent work in OPV and OPD research areas. First, I will discuss the importance of molecular design on efficiency and photostability of OPV materials with a particular focus on non-fullerene acceptors. Second, I will discuss the molecular origin of high-performance in OPD devices, showing the key differences between OPD and OPV devices in terms of their operational mechanisms and requirements for molecular design. As such, it is now critical to understand the molecular origins in much deeper detail than before to direct synthesis of organic semiconductors in more promising directions.