Improving Lattice Rigidity and Charge Carrier Lifetime by Engineering Spacer Cation of Ruddlesden–Popper Perovskites: A Time-Domain <i>Ab Initio</i> Study
Dandan Dai, Ran Shi, Run Long
Abstract
First-principles quantum dynamics calculations show that charge carrier lifetimes, charge transport, and lattice stability are notably improved when BA (CH3(CH2)3NH3+) in BA2PbI4 is replaced with MTEA (CH3(CH2)2SNH3+). By suppressing atomic fluctuations, MTEA enhances the lattice stiffness and inhibits loss of coherence due to the S–S interaction. By delocalizing hole wave functions on the MTEA, particularly on the S atoms, while maintaining the electron wave functions largely unchanged compared to the BA2PbI4, MTEA serves to enhance charge transport and NA coupling while narrowing the bandgap by 0.18 eV. Overall, MTEA decreases NA coupling due to slow atomic motions against a large overlap of electron–hole wave functions, which suppresses nonradiative electron–hole recombination and prolongs carrier lifetime twice longer compared with BA2PbI4. This simulation presents a rational route to make high performance two-dimensional perovskite solar cells.