Surfaces and Interfaces Eric Welch, Young-Kwang Jung, Luisa Scolfaro, Aron Walsh and Alex Zakhidov Texas State University Department of Physics Zakhidov Optoelectronics Group https://zakhidov.wp.txstate.edu In collaboration with the Material’s Design Group 1
State University Department of Physics ✅ Large bandgap: 𝐸$ = 3.1 𝑒𝑉 ✅ High RT conductivity: 𝜎 = 156 𝑆 𝑐𝑚"% ✅ High hole mobility: 𝜇 > 40 𝑐𝑚# 𝑉"% 𝑠"# ✅ Non-toxic ✅ Inexpensive precursors ✅ Less expensive than Spiro-OMETAD ✅ Non-porous/dense ✅ Comparable lattice constant to CsPbBr3 : CuI = 6.05 Å, CsPbBr3 = 5.83 Å Cu I 1. C. Yang, M. Kneiβ, M. Lorenz, and M. Grundmann, Proc. Natl. Acad. Sci. U. S. A. 113, 12929 (2016). 2. D. Chen, Y. Wang, Z. Lin, J. Huang, X. Chen, D. Pan, and F. Huang, Cryst. Growth Des. 10, 2057 (2010). 3. C Swartz et. al. Phys. Status Solidi A, 218, 2000721 (2021) 3
𝜎&'() is two times smaller than 𝜎&'* ❌ CuBr is $3/g more expensive than CuI Texas State University Department of Physics 1. D. Astadjov, et. al. IEEE J. Quant. Elec. 30, 1994. 4
terminated and CsBr terminated show lowest surface energies o Also need interface energy and bonding information to determine favorable interface termination Texas State University Department of Physics 1. E Welch et. al. AIP Advances. 10, 085023 (2020). 6
𝑡 − 𝐸()*+ ,(-+./! 𝑡 − 𝐸()*+ ,01 𝑡 ] o Interface energy reveals PbBr2 terminated CsPbBr3 on Cu terminated CuI to be the lowest energy Texas State University Department of Physics 1. E Welch et. al. AIP Advances. 10, 085023 (2020). 7
o Yellow (red) isosurfaces indicated positive/accumulation (negative/depletion) regions Texas State University Department of Physics 1. E Welch et. al. AIP Advances. 10, 085023 (2020). 8
barrier potential changes sign o Type I to type II potential barrier transition o 𝑉𝐵𝑂 𝐶𝐵𝑂 = Δ𝐸! Δ𝐸" + Δ𝑉 Texas State University Department of Physics 1. E Welch et. al. AIP Advances. 10, 085023 (2020). 9
growth o A stable interface exists where Cu is bonded to Br o Thickness is a tunable parameter o Our group recently showed CuI functions well as an HTL with MAPI for PV applications: C Swartz et. al. Phys. Status Solidi A, 218, 2000721 (2021) Texas State University Department of Physics 10
https://zakhidov.wp.txstate.edu In collaboration with the Material’s Design Group 11 Alex Zakhidov Luisa Scolfaro Young-Kwang Jung Aron Walsh @EricWelch31415 Funding: NSF #1927020 (Dr. Anna Bardy-Estevez) ONR N000141912576 (Dr. Paul Armistead) NRF MSIT 2018r1c1b6008728 This work has been published in: AIP Advances 10, 085023 (2020); https://doi.org/10.1063/5.0018925
g (21.65/5 g) • PbBr2: $53.20/5 g • Spiro-OMETAD: $1280/5 g • PEDOT:PSS: $42.30/5 g • TPBi: $391/500 mg (3910/5 g) • CuI: $6.55/5 g Texas State University Department of Physics 13 • Other LEDs • AlGaInN green LEDs: ~15% EQE