High-stability organic red-light photodetector for narrowband applications

Red-light photodetectors without filters are in urgent need for narrowband applications such as full-color imaging and multi-output visible light communication (VLC). However, their development is hindered by the lack of small-band-gap and narrowband response materials. Without wavelength filters, a new type of photodetector with a simple single-layer architecture is developed, based on a stable small-band-gap squarylium dye and characterized by a detectivity peak at 680 nm and full width at half maximum of 80 nm. The device, which exhibits high stability in air and humid conditions, shows a significantly low dark current of similar to 2 nA.cm(-2) at -2 V and high specific detectivity of 3.2 x 10(12) Jones. The response current ratio of the device to red, green, and blue lights with a luminous flux amplitude ratio of 3:6:1 (standard ratio for white light) is 100:12:1.1. These properties indicate that the squarylium dye red-light photodetectors are promising for VLC and other narrowband optoelectronic applications.