Thickness effect on the laser-induced thermoelectric voltage and laser-communication realization of the solution–derived inclined Bi2201 thin films

Thickness-dependent laser-induced thermoelectric voltage (LITV) effect via a semiconductor laser with a wavelength of 405 nm in the inclined solution-derived Bi₂Sr₂CuO_y (Bi2201) thin films has been studied. The high peak voltage of 47.6 mV under a power density of 50 mW/cm², and a large sensitivity of 0.93 ± 0.007 V·cm²/W (or 23.3 ± 0.18 V/mJ) are derived with the optimized thickness of 280 nm. The peak voltage demonstrates an initial increase and then a decrease with the increased film thickness, which is ascribed to the varied temperature difference caused by the gradually prolonged thermal transfer distance, increased light absorption, and enhanced electric conductance. Based on such LITV effect, the optical communication system composed of the transistor-transistor-logic modulated laser diode and the Bi2201 thin film was designed and realized. The separate and distinguished pseudorandom binary sequence can be transmitted and decoded correctly by this communication system. All these results will provide a way to optimize Bi2201 thin films with improved LITV and expand their performance in optical detection.

Graphical Abstract

Voltage self-produced makes the LITV effect important and valuable for broadband light detection. However, the expensive and large-sized excimer lasers restrict their practical application. Here, high peak voltage and large sensitivity with a commercial semiconductor laser are derived. Based on the optimized film device and its laser-induced self-produced voltage, optical communication was presented for the first time as one typical application of the LITV effect.