Optoelectronic Property Modulation in Chiral Organic Semiconductor/Polymer Blends.

Organic phototransistors (OPTs) have been widely used in biomedical sensing, optical communications, and imaging. Charge-trapping effect has been utilized as an effective strategy for enhancing their photoresponsivity by effectively decreasing the dark current. The combination of organic semiconductors (OSCs), especially chiral OSCs, with insulating polymers has rarely been carried out for optoelectronic applications. Here, we fabricated OPTs containing both enantiopure and racemic air-stable n-type perylene diimide derivatives, CPDI-CN2-C6, and insulating biopolymer polylactide (PLA) and evaluated their photoresponsive properties. The PLA-blended systems exhibited greatly enhanced optoelectronic performances owing to the intense charge-trapping effect. Interestingly, the racemic system showed 3 times higher electron mobility and 12 times higher specific detectivity (1.3 × 1013 jones) compared with the enantiopure systems due to the more aggregated morphologies and larger grains, indicating that chiral composition can be used as a tuning parameter in optoelectronic devices. Our systematic study provides a feasible and effective method for producing high-performance n-type OPTs under ambient conditions.