Doping and Mobility Limits of Cuprous Iodide

When and Where

Nov 29, 2022
2:00pm - 2:15pm

Sheraton, 2nd Floor, Republic B

Presenter

Joe Willis

Qi Zhou

David Scanlon

Co-Author(s)

Joe Willis^1,2,3,Qi Zhou¹,David Scanlon^1,2

University College London¹,Thomas Young Centre²,Diamond Light Source³

Abstract

Joe Willis^1,2,3,Qi Zhou¹,David Scanlon^1,2

University College London¹,Thomas Young Centre²,Diamond Light Source³

The quest for p-type transparent conducting materials has challenged researchers for decades. Initial efforts focused on designing p-type transparent conducting oxides, such as CuAlO2,[1] which generally display good transparency, but fail to reach competitive levels of conductivity. This is because the valence bands of such materials are dominated by highly localised oxygen p states, which trap hole polarons and severely limit the charge carrier mobility.[2] In recent years, research has moved more towards non-oxide materials that have greater delocalisation of the states at the valence band maximum in an effort to improve p-type conductivity.[3-5] One such material is cuprous iodide (CuI), which has an optical band gap just shy of 3 eV and displays intrinsic p-type conductivity that can be improved upon intentional doping.[6] The relatively disperse valence band maximum is formed from the broad overlap of Cu 3d and I 5p orbitals that suggests high hole mobility is possible. In this work, we investigate Se-doping in CuI using hybrid density functional theory. We compare defect formation energies to both experimentally and computationally determined values from the literature, and examine effects of the dopant on the electronic structure. We compute the charge transport properties of CuI using the AMSET package,[7] and determine the upper limit of hole mobility. We find that the relatively low dielectric response of CuI ultimately prevents hole mobility exceeding around 40 cm2 V-1 s-1 when degenerately doped. [1] Kawazoe, H. et al, Nature, 1997, 389, 939 [2] Scanlon, D. O. and Watson, G. W., J. Phys. Chem. Lett., 2010, 1, 3195 [3] Williamson, B. A. D. et al, Chem. Mater., 2017, 29, 2402 [4] Willis, J. and Scanlon, D. O., J. Mater. Chem. C, 2021, 9, 11995 [5] Willis, J. et al, Chem. Sci., 2022, 13, 5872 [6] Storm, P. et al, Phys. Status Solidi RRL, 2021, 15, 2100214 [7] Ganose, A. M. et al, Nat. Comms., 2021, 12, 2222