Conventional semiconductor devices are rigid. They also have scalability issues when a large device area and low cost are both required. My group focuses on synthesizing solution-processable semiconductors, developing semiconductor-polymer composites, and engineering their charge transportation across complex interfaces. The goal is to realize optoelectronic devices with semiconductor-polymer composites that harness the versatile mechanical properties and manufacturing advantages of commodity polymers. In the first part of my presentation, I will highlight two recent case studies in my group of using semiconductor-polymer composites to enable ultra-soft photodetectors for wearable photoplethysmography and overcome scalability limitations of radiation detectors. The second part of my presentation will focus on developing organometal halide perovskite/polymer composites towards fully printable light-emitting diodes (LEDs). Halide perovskite (ABX₃) are emerging semiconductors with astounding optoelectronic properties. Such materials are typically processed with a solution process to form polycrystalline thin films on substrates. However, the films tend to form pinholes and degrade in air. We discovered that both problems could be resolved by using perovskite/polymer composites. I will discuss how the structures of the polymers affected the morphology and electronic/ionic charge transport of perovskite crystals in the resulting composites. The optimized composites can be processed in humid air and possess the optoelectronic characteristics of pristine perovskites. Blue, green and red-emission LEDs had been demonstrated with device efficiencies that greatly exceeded those of pristine perovskite LEDs.

https://wustl.box.com/s/8m94u7f0h57yzyup5s9qi2hb8i0kgagm

Conventional semiconductor devices are rigid. They also have scalability issues when a large device area and low cost are both required. My group focuses on synthesizing solution-processable semiconductors, developing semiconductor-polymer composites, and engineering their charge transportation across complex interfaces. The goal is to realize optoelectronic devices with semiconductor-polymer composites that harness the versatile mechanical properties and manufacturing advantages of commodity polymers. In the first part of my presentation, I will highlight two recent case studies in my group of using semiconductor-polymer composites to enable ultra-soft photodetectors for wearable photoplethysmography and overcome scalability limitations of radiation detectors. The second part of my presentation will focus on developing organometal halide perovskite/polymer composites towards fully printable light-emitting diodes (LEDs). Halide perovskite (ABX₃) are emerging semiconductors with astounding optoelectronic properties. Such materials are typically processed with a solution process to form polycrystalline thin films on substrates. However, the films tend to form pinholes and degrade in air. We discovered that both problems could be resolved by using perovskite/polymer composites. I will discuss how the structures of the polymers affected the morphology and electronic/ionic charge transport of perovskite crystals in the resulting composites. The optimized composites can be processed in humid air and possess the optoelectronic characteristics of pristine perovskites. Blue, green and red-emission LEDs had been demonstrated with device efficiencies that greatly exceeded those of pristine perovskite LEDs.

https://wustl.box.com/s/8m94u7f0h57yzyup5s9qi2hb8i0kgagm