Lead-free double perovskite materials for photovoltaic application

This work consists in studying the implementation of double perovskite materials in the form of thin film and showing the effect of the deposition conditions on the structural properties (uniformity, coverage rate, roughness, thickness, crystallinity, crystallite size) and on the optoelectronic properties (light absorption, electron-hole pair generation efficiency, charge diffusion length, recombination...).
Before considering ultrasonic spray pyrolysis deposition, preliminary spin-coating tests are ongoing in order to verify the formation of Cs2AgBiBr6 phase according to the protocol reported by Greul et al. (J. Mater Chem A (2017), 19972-19981). The effect of precursors concentration, thermal post-treatment (hot plate/oven, temperature/duration), antisolvent dripping, relative humidity - which are reported as critical parameters for the preparation of high efficiency lead halides perovskite solar cells - on the layer morphology have been studied. The (micro)structural properties of the layers (uniformity, coverage rate, crystallite size, crystalline phase) have been characterized by scanning electron microscopy and X-ray diffraction. To improve charge collection within the lead-free double perovskite photoactive material, we have also investigated a mesoporous TiO2 network as an electron collecting material filled by Cs2AgBiBr6. Efficiencies of 1.7 % have been reached for our best PV cells which are very promising results.