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Toward Faster Organic Photodiodes: Tuning of Blend Composition Ratio
Author(s) -
Saggar Siddhartha,
Sanderson Stephen,
Gedefaw Desta,
Pan Xun,
Philippa Bronson,
Andersson Mats R.,
Lo ShihChun,
Namdas Ebinazar B.
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202010661
Subject(s) - photodiode , materials science , optoelectronics , electron mobility , heterojunction , polymer solar cell , dynamic range , organic solar cell , electron , optics , polymer , solar cell , composite material , physics , quantum mechanics
Abstract 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‐C 71 ‐butyric acid methyl ester (or PC 71 BM) 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 PC 71 BM 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.