First Principles Computation on the Photovoltaic and Thermoelectric Properties of MAPbI3-xClx Perovskites

This research employs the first principles computation to simulate the chlorine (Cl) doping effect with different proportion (x value) on the photovoltaic and thermoelectric properties of bulk mixed halide methyl-ammonium lead perovskites (MAPbI3-xClx). In the study, the density functional theory (DFT) and Boltzmann transport equation (BTE) are applied to calculate the optical band gaps, electrical conductivity , carrier thermal conductivity , and Seebeck coefficient S. The density functional perturbation theory (DFPT) and Debye model are used to calculate the phonon thermal conductivity . Tuning the greatest thermoelectric figure of merit (ZT) with suitable solar absorbance range is the major target for our solar thermoelectric chip design. The simulation results reveal that doping Cl will increase the electronic conductivity, phonon thermal conductivity, and causes a blue shift in the light absorption. The main contribution to the total thermal conductivity is mainly from optical phonons, and the main absorbance wavelength locates in the ultraviolet and visible light region (40nm <  < 700nm). When x=0.25, MAPbI2.75Cl0.25 achieves the optimized tuning for both light absorption coefficient α and figure of merit ZT in our simulation cases.