Lead-free perovskites Perovskite 2 Built-in electric field 1 Built-in electric fields 1 Bulk charge 1 Bulk charge recombination 1 Charge recombinations 1 DFT study 1 Dielectric losses 1 Dielectric materials 1 Dielectric properties 1 Dimethylformamide 1 Eco-friendly 1 Efficiency 1 Electric fields 1 Electric losses 1 Energy gap 1 First principle calculations 1 Gradient FASnI3 absorber 1 Lead-Free 1 Lead-free perovskite solar cell 1 MASnCl3 perovskites 1 N ,N-Dimethylformamide 1 Open circuit voltage 1 Optical and dielectric properties 1 Optical properties 1 Optoelectronic applications 1 Organic solvents 1 Performance 1 Perovskite solar cells 1