Interface Engineering via Photopolymerization-Induced Phase Separation for Flexible UV-Responsive Phototransistors

Interface engineering has been recognized to be substantially critical for achieving efficient charge separation, charge carrier transport, and enhanced device performance in emerging optoelectronics. Nevertheless, precise control of the interface structure using current techniques remains a formidable challenge. Herein, we demonstrate a facile and versatile protocol wherein in situ thiol-ene click photopolymerization-induced phase separation is implemented for constructing heterojunction semiconductor interfaces. This approach generates continuous mountainlike heterojunction interfaces that favor efficient exciton dissociation at the interface while providing a continuous conductive area for hole transport above the interface. This facile low-temperature paradigm presents good adaptability to both rigid and flexible substrates, offering high-performance UV-responsive phototransistors with a normalized detectivity up to 6.3 × 10¹⁴ cm Hz^1/2 W^-1 (also called jones). Control experiments based on ex situ photopolymerization and in situ thermal polymerization are also implemented to demonstrate the superiority of this novel paradigm.