Toward faster organic photodiodes: tuning of blend composition ratio

Saggar, Siddhartha, Sanderson, Stephen, Gedefaw, Desta, Pan, Xun, Philippa, Bronson, Andersson, Mats R., Lo, Shih-Chun, and Namdas, Ebinazar B. (2021) Toward faster organic photodiodes: tuning of blend composition ratio. Advanced Functional Materials, 2021. 2010661.

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The ability of a light-sensor to detect fast variation in incident light intensity is a vital feature required in imaging and data transmission applications. Solution-processed bulk heterojunction (BHJ) type organic photodiodes (OPDs) have gone through key developments, including dark current mitigation and longer linear dynamic range. In contrast, there has been less focus on increasing OPD response speed (f–3dB). Here, bulk heterojunction OPDs based on electron-donating polymer poly[thiophene-2,5-diyl-alt-5,10-bis((2-hexyldecyl)oxy)dithieno[3,2-c:3′,2′-h][1,5]naphthyridine-2,7-diyl] (or PTNT) and electron-accepting phenyl-C71-butyric acid methyl ester (or PC71BM) are reported. The intrinsic charge transport characteristics required for fast speed OPDs are discussed, and an analytical model for the same is developed. The OPDs present 0.8 MHz f–3dB under no applied voltage bias for a typical blend ratio of 1:1 by weight. It is shown that balanced electron and hole mobility is a critical criterion for faster speed OPDs, which can be realized by tuning the composition ratio of the bulk heterojunction. By tuning PTNT and PC71BM blend ratio, the f–3dB was successfully raised by more than quadruple to 4.5 MHz. The findings provide a tool to set device architecture for faster next-generation light sensors.

Item ID: 67905
Item Type: Article (Research - C1)
ISSN: 1616-3028
Copyright Information: © 2021 Wiley-VCH GmbH
Funders: Australian Research Council (ARC), Department of Industry, Innovation and Science (DIIS)
Projects and Grants: ARC DP200103036, ARC DP17010246, DIIS AISRF5376
Date Deposited: 24 Jun 2021 03:16
FoR Codes: 40 ENGINEERING > 4016 Materials engineering > 401608 Organic semiconductors @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280110 Expanding knowledge in engineering @ 100%
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