Tuning the Excited-State Dynamics of CuI Films with Electrochemical Bias

Gergely F Samu; Rebecca A Scheidt; Ádám Balog; Csaba Janáky; Prashant V Kamat

doi:10.1021/acsenergylett.9b00182

Tuning the Excited-State Dynamics of CuI Films with Electrochemical Bias

ACS Energy Lett. 2019 Mar 8;4(3):702-708. doi: 10.1021/acsenergylett.9b00182. Epub 2019 Feb 13.

Authors

Gergely F Samu^{1

2

3}, Rebecca A Scheidt^{1

4}, Ádám Balog², Csaba Janáky^{2

3}, Prashant V Kamat^{1

4}

Affiliations

¹ Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, United States.
² Department of Physical Chemistry and Materials Science, Interdisciplinary Excellence Centre, University of Szeged, Rerrich Square 1, Szeged H-6720, Hungary.
³ ELI-ALPS Research Institute, Dugonics Square 13, Szeged 6720, Hungary.
⁴ Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.

Abstract

Owing to its high hole conductivity and ease of preparation, CuI was among the first inorganic hole-transporting materials that were introduced early on in metal halide perovskite solar cells, but its full potential as a semiconductor material is still to be realized. We have now performed ultrafast spectroelectrochemical experiments on ITO/CuI electrodes to show the effect of applied bias on the excited-state dynamics in CuI. Under operating conditions, the recombination of excitons is dependent on the applied bias, and it can be accelerated by decreasing the potential from +0.6 to -0.1 V vs Ag/AgCl. Prebiasing experiments show the persistent and reversible "memory" effect of electrochemical bias on charge carrier lifetimes. The excitation of CuI in a CuI/CsPbBr₃ film provides synergy between both CuI and CsPbBr₃ in dictating the charge separation and recombination.