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Title: Bulk- and layer-heterojunction phototransistors based on poly [2-methoxy-5-(2′-ethylhexyloxy-p-phenylenevinylene)] and PbS quantum dot hybrids

The responsivity (R) of a thin film photodetector is proportional to the product of its photo-induced carrier density (n) and mobility (μ). However, when choosing between layer heterojunction (LH) and bulk heterojunction (BH) field-effect phototransistors (FEpTs), it is still unclear which of the two device structures is more conducive to photodetection. A comparison study is performed on the two structures based on polymer and PbS quantum dot hybrids. Both devices exhibit ambipolar behavior, with μ{sub E} ≈ μ{sub H} = 3.7 cm{sup 2} V{sup −1} s{sup −1} for BH-FEpTs and μ{sub H} = 36 cm{sup 2} V{sup −1} s{sup −1} and μ{sub E} = 52 cm{sup 2} V{sup −1} s{sup −1} for LH-FEpTs. Because of the improvements in μ and the channel order degree (α), the responsivity of LH-FEpTs is as high as 10{sup 1 }A/W, which is as much as two orders of magnitude higher than that of BH-FEpTs (10{sup −1}A/W) under the same conditions. Although the large area of the BH improves both the exciton separation degree (β) and n in the BH-FEpT, the lack of an effective transport mechanism becomes the main constraint on high device responsivity. Therefore, LH-FEpTs are better candidates for use as photo detectors, and a “three-high” principle of high α, β, and μ is foundmore » to be required for high responsivity.« less
Authors:
; ; ; ; ; ; ; ; ; ;  [1] ;  [2] ;  [3]
  1. Institute of Laser and Opto-Electronics, College of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072 (China)
  2. (Tianjin University), Ministry of Education, Tianjin 300072 (China)
  3. Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China)
Publication Date:
OSTI Identifier:
22483099
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 25; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARRIER DENSITY; HETEROJUNCTIONS; LAYERS; LEAD SULFIDES; PHOTODETECTORS; PHOTOTRANSISTORS; POLYMERS; QUANTUM DOTS; THIN FILMS