Pressure dependence of excited-state charge-carrier dynamics in organolead tribromide perovskites

Abstract

Excited-state charge-carrier dynamics governs the performance of organometal trihalide perovskites (OTPs) and is strongly influenced by the crystal structure. Characterizing the excited-state charge-carrier dynamics in OTPs under high pressure is imperative for providing crucial insights into structure-property relations. Here, we conduct in situ high-pressure femtosecond transient absorption spectroscopy experiments to study the excited-state carrier dynamics of CH3NH3PbBr3 (MAPbBr3) under hydrostatic pressure. The results indicate that compression is an effective approach to modulate the carrier dynamics of MAPbBr3. Across each pressure-induced phase, carrier relaxation, phonon scattering, and Auger recombination present different pressure-dependent properties under compression. Responsiveness is attributed to the pressure-induced variation in the lattice structure, which also changes the electronic band structure. Specifically, simultaneous prolongation of carrier relaxation and Auger recombination is achieved in the ambient phase, which is very valuable for excess energy harvesting. Our discussion provides clues for optimizing the photovoltaic performance of OTPs.

Pressure Engineered Optical Properties and Carrier Dynamics of FAPbBr3 Nanocrystals Encapsulated by Siliceous Nanosphere

“…As shown in Figure c, the fast lifetime (τ 2 ) gradually becomes slower before 0.6 GPa and then the lifetime remains almost the same until the phase transition of the sample. Compared with the other literature, it is found that the lifetime in this time range should be related to the Auger recombination of carriers. − According to the assignment of Auger recombination, we have carried out the excitation power dependent TA spectroscopy experiment of FAPbBr 3 @SiO 2 NCs at atmospheric pressure. Figure S9 shows the measured B1 kinetic traces at different excitation fluences.…”

Lighting Up the Invisible Twisted Intramolecular Charge Transfer State by High Pressure

“…The details for the femtosecond transient absorption apparatus are discussed elsewhere. − The femtosecond laser (Coherent Libra, U.S.) source was an all-in-one ultrafast oscillator and a regenerative amplifier. The laser system provided 4 mJ pulses with a repetition rate of 1000 Hz.…”

Anti-correlation between Band gap and Carrier Lifetime in Lead Halide Perovskites under Compression Rationalized by Ab Initio Quantum Dynamics

“…Pressure treatment can compress the lattice and tune the electronic structure, which can result in novel physical properties. Several teams used hydrostatic pressure to precisely regulate the compressible perovskite crystal structure. − In response to pressure, lead halide perovskites experience changes in the Pb–X bond lengths and the Pb–X–Pb bond angles, allowing one to modulate perovskite structural and electronic properties without the need to adjust the chemical compositions.…”

“…Investigation of charge carrier dynamics in perovskites is a relatively unexplored area, especially computationally, because it requires unconventional simulation tools, such as those developed in our group. , Such investigations are particularly important because carrier lifetime is one of the key parameters that determine solar cell performance. Recently, investigations of pressure-induced effects in MA and formamidinium (FA)-based lead halide perovskites have uncovered unusual phenomena, associated with structure changes and charge recombination dynamics. ,,, By applying mild pressure, Kong et al have demonstrated that the [PbI 6 ] 4– octahedra in MAPbI 3 undergo substantial distortions, resulting in simultaneous band gap narrowing and carrier lifetime prolongation . Such inverse correlation between the band gap and the lifetime is unexpected because according to the common arguments, such as the energy gap law, lower energy gaps are associated with reduced excited state lifetimes.…”