Doping optimization of organic-inorganic hybrid perovskite CH3NH3PbI3 for high thermoelectric efficiency

The newly discovered photovoltaic hybrid perovskite materials have been suggested for thermoelectric applications as they possess very low thermal conductivity and large Seebeck coefficient. However, to achieve a high figure of merit, chemical doping is necessary to increase the electrical conductivity. In the present work, we examined the thermoelectric figure of merit for CH3NH3PbI3 as a function of carrier concentration based on first-principles calculations. For doped semiconductors, the impurity scattering usually plays a dominant role in the charge transport. Both impurity scattering and acoustic phonon scattering have been incorporated in our calculations. We showed that at the impurity concentration of 10(18) cm(-3), the room temperature zT value of tetragonal CH3NH3PbI3 could be optimized to reach unity at the carrier concentration on the same order of magnitude as 10(18) cm(-3). The hole-doped CH3NH3PbI3 exhibits superior thermoelectric property than the electron-doped one, and we propose to engineer the vacancies of organic cations for the enhanced hole concentration and thermoelectric efficiency. (C) 2017 Elsevier B.V. All rights reserved.