Flexible Phototransistors Integrated with Chiral Liquid\nCrystal Encapsulating Film for Improving Color Selectivity and Stability

Organic\nphototransistors (OPTs), which have optical signal detection,\nsignal amplification, and mechanical flexibility, are fundamental\nbuilding blocks of flexible and wearable optoelectronics. For the\npractical application of the OPTs, color selectivity for accurate\noptical signal processing is essential. Additionally, a high electrical\nstability should be guaranteed against environmental factors. Here,\nwe propose a flexible OPT that achieves both color selectivity and\nenvironmental stability through a single encapsulating layer made\nof a chiral liquid crystal (CLC) polymer. This CLC polymer has a unique\noptical property called selective wavelength reflection, which can\nbe precisely tailored to the color selectivity of the OPTs. Additionally,\nthe CLC film demonstrates moisture resistance, allowing the proposed\ndevice to operate stably under ambient conditions. This multifunctional\nencapsulating layer is integrated on the OPT through a simple transfer\nprocess. The straightforward yet effective concept of integrating\nCLC films into OPTs is expected to provide a platform for the development\nof next-generation flexible optoelectronic devices.