Hot Carrier and Surface Recombination Dynamics in Layered InSe Crystals

Chengmei Zhong, Vinod K. Sangwan, Joohoon Kang, Jan Luxa, Zdeněk Sofer, Mark C. Hersam*, Emily A. Weiss

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Layered indium selenide (InSe) is a van der Waals solid that has emerged as a promising material for high-performance ultrathin solar cells. The optoelectronic parameters that are critical to photoconversion efficiencies, such as hot carrier lifetime and surface recombination velocity, are however largely unexplored in InSe. Here, these key photophysical properties of layered InSe are measured with femtosecond transient reflection spectroscopy. The hot carrier cooling process is found to occur through phonon scattering. The surface recombination velocity and ambipolar diffusion coefficient are extracted from fits to the pump energy-dependent transient reflection kinetics using a free carrier diffusion model. The extracted surface recombination velocity is approximately an order of magnitude larger than that for methylammonium lead-iodide perovskites, suggesting that surface recombination is a principal source of photocarrier loss in InSe. The extracted ambipolar diffusion coefficient is consistent with previously reported values of InSe carrier mobility.

Original languageEnglish (US)
Pages (from-to)493-499
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume10
Issue number3
DOIs
StatePublished - Feb 7 2019

Funding

This research was supported by the Materials Research Science and Engineering Center (MRSEC) of Northwestern University (NSF DMR-1720139) (spectroscopy) and the Center for Light Energy Activated Redox Processes (LEAP), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0001059 (sample preparation and characterization). Z.S. and J.L. were supported by the Czech Science Foundation (GACR No. 17-11456S), Neuron Foundation for scientific support, and by the project Advanced Functional Nanorobots (Reg. No. CZ.02.1.01/0.0/0.0/15_003/0000444 financed by the EFRR).

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry

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