Cavity-Enhanced Near-Infrared Organic Photodetectors Based on a Conjugated Polymer Containing [1,2,5]Selenadiazolo[3,4-<i>c</i>]Pyridine

Abstract

Miniaturization of spectrometers can be achieved using an array of narrowband photodetectors responsive at specific wavelengths. In this work, sensitive organic narrowband photodetectors with tunable spectral response in the near-infrared (NIR) wavelength range are demonstrated. This is achieved using a resonant optical-cavity device architecture based on a thick ZnO spacer to increase the weak NIR absorption of a low-band gap conjugated polymer containing [1,2,5]selenadiazolo[3,4-c]pyridine. We realize spectral response full-width at half-maximum (FWHM) values down to 22 nm and achieve calculated peak specific detectivity (D*) over 1011 Jones in these cavity-enhanced photodetectors. More importantly, we achieve continuously tuned detection wavelengths over a wide wavelength range of 660–1510 nm. This allows for a proof-of-concept demonstration of a miniaturized spectrometer for the NIR wavelength range and can resolve the NIR characteristic absorption bands of water, ethanol, and acetone.