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Polymer:Fullerene Bimolecular Crystals for Near‐Infrared Spectroscopic Photodetectors
Author(s) -
Tang Zheng,
Ma Zaifei,
SánchezDíaz Antonio,
Ullbrich Sascha,
Liu Yuan,
Siegmund Bernhard,
Mischok Andreas,
Leo Karl,
CampoyQuiles Mariano,
Li Weiwei,
Vandewal Koen
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201702184
Subject(s) - materials science , photodetection , optoelectronics , photodetector , organic semiconductor , photodiode
Spectroscopic photodetection is a powerful tool in disciplines such as medical diagnosis, industrial process monitoring, or agriculture. However, its application in novel fields, including wearable and biointegrated electronics, is hampered by the use of bulky dispersive optics. Here, solution‐processed organic donor–acceptor blends are employed in a resonant optical cavity device architecture for wavelength‐tunable photodetection. While conventional photodetectors respond to above‐gap excitation, the cavity device exploits weak subgap absorption of intermolecular charge‐transfer states of the intercalating poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (PBTTT):[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) bimolecular crystal. This enables a highly wavelength selective, near‐infrared photoresponse with a spectral resolution down to 14 nm, as well as dark currents and detectivities comparable with commercial inorganic photodetectors. Based on this concept, a miniaturized spectrophotometer, comprising an array of narrowband cavity photodetectors, is fabricated by using a blade‐coated PBTTT:PCBM thin film with a thickness gradient. As an application example, a measurement of the transmittance spectrum of water by this device is demonstrated.