Paper-based mixed-cation perovskite for optical terahertz modulation

The synthesis and optimization of FAxMA1−xPbBr3 mixed-cation perovskites, including the pure MAPbBr3 and FAPbBr3 phases, are reported. A stable performance enhancement was demonstrated by the polycrystalline sample with an optimized cation stoichiometry (x = 0.5, FA0.5MA0.5PbBr3) when grown on a paper. Under a laser density of 1.35 W/cm2, a terahertz frequency-domain modulation of 31.1% was achieved by paper-based FA0.5MA0.5PbBr3. The origin of the enhancement was confirmed through photocurrent and amplified spontaneous emission measurements to be a substantial increase in the internal photogenerated carrier concentration under optical excitation. These superior properties are attributed to the synergistic effects of cation mixing, which improves structural and optoelectronic stabilities, and the paper substrate, which enhances light harvesting and charge carrier dynamics.