Black silicon as absorber for photo-thermal-electric devices

Black silicon was fabricated by a metal catalytic chemical etching method, and an average absorption of 90% in 250–2500 nm was achieved. The photo-thermal conversion properties of the black silicon were investigated using 808 nm and 1319 nm lasers. As a broadband light energy absorber, the black silicon was then pasted on a thermoelectric module, and its photo-thermal-electric conversion characteristics were investigated. As an insulating layer, a polystyrene layer was covered on the black silicon, which notably improved the photo-thermal converting efficiency. As opposed to photovoltaic devices, this low-cost device exhibits electric responses to both the intrinsic absorption band and the extrinsic absorption band, which could open up new paths for fully utilizing the absorption band of black silicon.