PHOTOCONDUCTIVITY DYNAMICS OF BLADE COATED CESIUM LEAD TRIBROMIDE THIN FILMS
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Lead halide perovskites (LHPs) have attracted attention recently as building blocks for the next generation of solar cells. These systems typically consist of multiple mobile components - vacancies, defects, electrons, and ions, leading to complicated charge carrier dynamics, both in the dark and in the photo-excited state. To understand the structure-property-processing relationships in LHPs, we grow perovskite films under a variety of conditions, and then measure their electrical properties. In this work, we use electrical scanning probe microscopy methods to probe the conductivities of CsPbBr3 thin films made by a single step, manual blade-coating method. CsPbBr3 films were made using both dimethyl sulfoxide (DMSO) as a solvent, and a mixture of dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) as a solvent. Different annealing profiles and temperatures were employed to create different grain sizes and phases in the film. Broadband local dielectric spectroscopy (BLDS) measurements revealed an essentially light-independent conductivity for perovskites in the orthorhombic phase, for different solvent mixtures and annealing profiles. BLDS revealed the presence of light dependent photoconductivity in the cubic phase. The photoconductivity induced by phase transformation in the CsPbBr3 was quantified and the dependence of total light-induced conductivity on perovskite phase was established.