Premium
Near‐Infrared Organic Phototransistors with p‐Channel Photosensitive Layers of Conjugated Polymer Composed of bis‐Octyldodecyl‐Diketopyrrolopyrrole and Benzothiadiazole Units
Author(s) -
Park Jisu,
Lee Chulyeon,
Kim Taehoon,
Kim Hwajeong,
Kim Youngkyoo
Publication year - 2021
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.202000932
Subject(s) - materials science , photocurrent , optoelectronics , conjugated system , polymer , composite material
A near‐infrared (NIR)‐absorbing conjugated polymer, poly[{2,5‐bis‐(2‐octyldodecyl)‐3,6‐bis‐(thien‐2‐yl)‐pyrrolo[3,4‐ c ]pyrrole‐1,4‐diyl}‐ co ‐{2,2′‐(2,1,3‐benzothiadiazole)‐5,5′‐diyl}] (PODTPPD‐BT), which is synthesized via a Stille coupling reaction, can play a dual role (charge transport and sensing) in NIR‐sensing organic phototransistors (OPTRs). The PODTPPD‐BT films, which feature two strong optical absorption peaks at wavelengths (λ) of 830 and 935 nm, possess a highly ordered crystalline state as evidenced by the synchrotron radiation grazing incidence X‐ray diffraction (GIXD) method. The OPTRs with the PODTPPD‐BT layers show typical p‐channel transistor behaviors in the dark, while their best dark performance is measured at a PODTPPD‐BT thickness ( t ) of 85 nm. The highest overall photocurrent is measured at t = 85 nm under illumination with three monochromatic NIR lights, while the highest photoresponsivity ( R C ) is obtained for the thickest PODTPPD‐BT layers ( t = 145 nm). The flexible OPTRs with the PODTPPD‐BT layers demonstrate stable sensing characteristics upon optical on/off modulations using a high‐power NIR laser diode (λ = 905 nm) used for actual light detection and ranging (LiDAR) systems.