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

- Thermoelectric properties of CH3NH3PbI3 perovskite were investigated by first-principles calculations.
- Tetragonal CH3NH3PbI3 was found to possess larger zT values than cubic one.
- zT value of p-type tetragonal CH3NH3PbI3 exceeded unity at the optimal doping level.
- Hole-doping optimization by engineering vacancies of organic cations was proposed.

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 1018 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 1018 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.

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