Optimizing the quasi-equilibrium state of hot carriers in all-inorganic lead halide perovskite nanocrystals through Mn doping: fundamental dynamics and device perspectives.
Jie MengZhenyun LanWeihua LinMingli LiangXianshao ZouQian ZhaoHuifang GengIvano Eligio CastelliSophie E CantonTõnu PulleritsKaibo ZhengPublished in: Chemical science (2022)
Hot carrier (HC) cooling accounts for the significant energy loss in lead halide perovskite (LHP) solar cells. Here, we study HC relaxation dynamics in Mn-doped LHP CsPbI 3 nanocrystals (NCs), combining transient absorption spectroscopy and density functional theory (DFT) calculations. We demonstrate that Mn 2+ doping (1) enlarges the longitudinal optical (LO)-acoustic phonon bandgap, (2) enhances the electron-LO phonon coupling strength, and (3) adds HC relaxation pathways via Mn orbitals within the bands. The spectroscopic study shows that the HC cooling process is decelerated after doping under band-edge excitation due to the dominant phonon bandgap enlargement. When the excitation photon energy is larger than the optical bandgap and the Mn 2+ transition gap, the doping accelerates the cooling rate owing to the dominant effect of enhanced carrier-phonon coupling and relaxation pathways. We demonstrate that such a phenomenon is optimal for the application of hot carrier solar cells. The enhanced electron-LO phonon coupling and accelerated cooling of high-temperature hot carriers efficiently establish a high-temperature thermal quasi-equilibrium where the excessive energy of the hot carriers is transferred to heat the cold carriers. On the other hand, the enlarged phononic band-gap prevents further cooling of such a quasi-equilibrium, which facilitates the energy conversion process. Our results manifest a straightforward methodology to optimize the HC dynamics for hot carrier solar cells by element doping.
Keyphrases
- solar cells
- room temperature
- density functional theory
- transition metal
- molecular dynamics
- high temperature
- molecular dynamics simulations
- single molecule
- high resolution
- metal organic framework
- energy transfer
- ionic liquid
- molecular docking
- blood brain barrier
- brain injury
- subarachnoid hemorrhage
- quantum dots
- high speed
- cerebral ischemia
- cross sectional
- weight loss
- crystal structure