Visible-light communication using thermally evaporated CsPbBr3 perovskite thin films

Lead halide perovskites are widely used in optoelectronic applications owing to their promising photophysical properties, but developing components of the order of nanoscale remains challenging. In this work, the authors fabricated cesium lead bromide (CsPbBr3) thin films of varying thicknesses and investigated their visible-light communication (VLC) performance. The thickness of the CsPbBr3 thin films was precisely controlled by using a single-beam thermal evaporation technique, and their morphology was analyzed through scanning electron microscopy and x-ray diffraction. Thicker films were found to have a homogeneous surface, with gain boundaries of increasing size and fewer surface trap states than the thinner films. Furthermore, we identified the thickness-dependent photoluminescence (PL) property of the CsPbBr3 thin films based on steady-state PL measurements and verified it by using time-correlated single-photon counting as well as femtosecond upconversion measurements. Films with thicknesses of 5, 10, and 20 nm, with enhanced surface homogeneity and purity, were used in a VLC link as color-converting fluorescent components. The 20-nm-thick CsPbBr3 film delivered the best performance because it had the highest PL intensity and the most suitable morphology, with a –3-dB bandwidth of 30.7 MHz and a net data rate of 330 Mb/s. These results reflect a facile and well-controlled approach to fabricating such films that can be used for high-power, high-speed, and large-area transmission and detection of visible-light signals.