title: Organic phototransistors with nanoscale phase-separated polymer/polymer bulk heterojunction layers.
abstract: Low-cost detectors for sensing photons at a low light intensity are of crucial importance in modern science. Phototransistors can deliver better signals of low-intensity light by electrical amplification, but conventional inorganic phototransistors have a limitation owing to their high temperature processes in vacuum. In this work, we demonstrate organic phototransistors with polymer/polymer bulk heterojunction blend films (mixtures of p-type and n-type semiconducting polymers), which can be fabricated by inexpensive solution processes at room temperature. The key idea here is to effectively exploit hole charges (from p-type polymer) as major signaling carriers by employing p-type transistor geometry, while the n-type polymer helps efficient charge separation from excitons generated by incoming photons. Results showed that the present organic transistors exhibited proper functions as p-type phototransistors with ∼4.3 A W(-1) responsivity at a low light intensity (1 µW cm(-2)), which supports their encouraging potential to replace conventional cooled charge coupled devices (CCD) for low-intensity light detection applications.
authors.affiliation: Organic Nanoelectronics Laboratory, Department of Chemical Engineering, Kyungpook National University, Daegu, 702-701, Republic of Korea.
authors.forename: Hyemin
authors.initials: H
authors.lastname: Hwang
authors.forename: Hwajeong
authors.initials: H
authors.lastname: Kim
authors.forename: Sungho
authors.initials: S
authors.lastname: Nam
authors.forename: Donal D C
authors.initials: DD
authors.lastname: Bradley
authors.forename: Chang-Sik
authors.initials: CS
authors.lastname: Ha
authors.forename: Youngkyoo
authors.initials: Y
authors.lastname: Kim
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007204:Indium / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D009930:Organic Chemicals / Q000737:chemistry*; D044367:Phase Transition; D010783:Photometry / Q000295:instrumentation*; D011108:Polymers / Q000737:chemistry*; D014173:Transistors, Electronic
chemical_list: D009930:Organic Chemicals; D011108:Polymers; D007204:Indium