Flexible and Air‐Stable Near‐Infrared Sensors Based on Solution‐Processed Inorganic–Organic Hybrid Phototransistors

Abstract Flexible and air‐stable phototransistors are highly demanded for wearable near‐infrared (NIR) image sensors. However, advanced NIR sensors via low‐cost, solution‐based processes remained a challenge. Herein, high‐performance inorganic–organic hybrid phototransistors are achieved based on solution processed n‐type metal oxide/polymer semiconductor heterostructures of In 2 O 3 /poly{5,5′‐bis[3,5‐bis(thienyl)phenyl]‐2,2′‐bithiophene‐3‐ethylesterthiophene]} (PTPBT‐ET). The In 2 O 3 /PTPBT‐ET hybrid phototransistor combines the advantages of both fast electron transport in In 2 O 3 and high photoresponse in PTPBT‐ET, showing high saturation mobility of 7.1 cm 2 V −1 s −1 and large current on/off ratio of >10 7 . As a result, the phototransistor exhibits high performance towards NIR light sensing with a responsivity of 200 A W −1 , a specific detectivity of 1.2 × 10 13 Jones, and fast photoresponse with rise/fall time of 5/120 ms. Remarkably, the hybrid phototransistor, without any passivation, demonstrates excellent electrical stability without performance degradation even after 160 days in air. A 10 × 10 phototransistor array is also enabled by virtue of the high device uniformity. Lastly, flexible In 2 O 3 /PTPBT‐ET phototransistor on polyimide substrate is attained, exhibiting outstanding mechanical flexibility up to 1000 bending/releasing cycles at a bending radius of 5 mm. These achievements pave the way for constructing air‐stable hybrid phototransistors for flexible NIR image sensor applications.