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Updated: May 20, 2025

Carrier Lifetime Measurements in Semiconductors through the Microwave Photoconductivity Decay Method
Published on: April 18, 2019
Enhancing the Photoexcited Carrier Spin Relaxation Lifetime in CsPbBr3 Perovskite Quantum Dots by 208Pb Isotope
Vivien L Cherrette1, David Zeitz1, Mariam Khvichia1
1Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States.
Abstract:
CsPbBr3 perovskite quantum dot (PQD) films enriched with 208Pb (I = 0) or 207Pb (I = 1/2) isotope were used to study the effect of nuclear spin on the photoexcited carrier spin relaxation using circularly polarized femtosecond transient absorption spectroscopy at 293 and 77 K. At 293 K, the short carrier spin relaxation lifetimes of 208Pb-enriched PQDs (2.0 ps) and natPb PQDs (0.70 ps) indicate that electron-phonon interactions dominate. At 77 K, the 207Pb-enriched PQD carrier spin relaxation lifetime was not detectible within the instrumental limit (<0.30 ps). However, the carrier spin relaxation lifetime increased to 5.0 ps for natPb PQDs and 170 ps for 208Pb-enriched PQDs. The dramatic increase in the 208Pb-enriched PQD carrier spin relaxation lifetime suggests that decreasing the concentration of 207Pb in the PQDs can reduce spin decoherence from nuclear spin-carrier spin coupling and enhance the lifetime.
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