Bi-based perovskite-derivates with significant Seebeck coefficients

Heat is an inexhaustible source of energy and stimuli. Thermoelectric generators and thermal sensors can produce power or an electrical signal, harvesting the waste heat. The search for a material that could be low cost, guarantee high efficiencies and be directly scalable has drawn attention to the family of halide perovskites. Here, we report bismuth-based perovskite-derivates to be used in thermal harvesting applications and suggest a path to increase the electrical conductivity by applying the mixed-anion approach, where the halide was partially substituted with sulphur to reduce the electrical resistivity. The layers were produced by drop-casting or spin coating; bismuth tri-ethylxanthate has been successfully used as a sulphur source. The Seebeck coefficients measured were higher than 40 mV K-1 in doped and undoped bismuth-based perovskite-derivates. Here, we present an extensive result discussion, based on Raman spectroscopy, X-ray diffraction, UV–visible characterization, ultra-violet, X-ray and inverse photoemission spectroscopies, SEM and EDS analysis. The significant Seebeck coefficient and the micrometre-sized sample dimensions make these compounds highly attractive for heat-flow sensing applications and, above all, for those technologies requiring miniaturised and flexible devices.