Electron–acoustic phonon coupling in single crystal CH ₃NH ₃PbI ₃ perovskites revealed by coherent acoustic phonons

Abstract

Despite the great amount of attention CH ₃NH ₃PbI ₃ has received for its solar cell application, intrinsic properties of this material are still largely unknown. Mobility of charges is a quintessential property in this aspect; however, there is still no clear understanding of electron transport, as reported values span over three orders of magnitude. Here we develop a method to measure the electron and hole deformation potentials using coherent acoustic phonons generated by femtosecond laser pulses. We apply this method to characterize a CH ₃NH ₃PbI ₃ single crystal. We measure the acoustic phonon properties and characterize electron-acoustic phonon scattering. Then, using the deformation potential theory, we calculate the carrier intrinsic mobility and compare it to the reported experimental and theoretical values. Our results reveal high electron and hole mobilities of 2,800 and 9,400 cm ² V ⁻¹ s ⁻¹, respectively. Comparison with literature values of mobility demonstrates the potential role played by polarons in charge transport in CH ₃NH ₃PbI ₃.

Abstract

Carrier mobility is a basic semiconductor property. Mante et al., use femtosecond lasers to investigate coherent acoustic phonons and relate their deformation potentials to estimate the intrinsic electron and hole mobilities of CH ₃NH ₃PbI ₃ single crystals to be 2,800 and 9,400 cm ² V ⁻¹ s ⁻¹, respectively.