Influence of surface termination on the structural and electronic properties at the Pb-free perovskite/charge transport material interfaces

Pingping JIANG^a, Boubacar TRAORE^b, Mikael KEPENEKIAN^b, George VOLONAKIS^b, Claudine KATAN^b, Laurent PEDESSEAU^a, Jacky EVEN^a

^aUniversité Rennes, INSA Rennes, CNRS, Institut FOTON, Place Recteur Henri le Moal, Rennes, France

^bUniv Rennes, ENSCR, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France

Proceedings of International Conference on Emerging Light Emitting Materials (EMLEM22)

Materials for next generation LEDs and lasers:

Limasol, Cyprus, 2022 October 3rd - 5th

Organizers: Maksym Kovalenko, Maryna Bodnarchuk and Grigorios Itskos

Oral, Pingping JIANG, presentation 029
DOI: https://doi.org/10.29363/nanoge.emlem.2022.029
Publication date: 15th July 2022

To cope with the toxicity of Pb-based perovskites and achieve smaller electronic band gaps, replacing Pb with Sn has gained growing attention recently ^1,2. Importantly, the low-bandgap Pb-Sn alloyed perovskite allows the building of all-perovskite tandem solar cells that shall overcome the performances of single-junction perovskite cells ^3,4. In fact, of all possible means to improve perovskite film quality and suppress nonradiative recombination in optoelectronic devices for a high photo conversion efficiency purpose, the surface and interface functionalizations after the assembly with charge transport layer (CTL) are one of the most critical parameters ^5,6. In view of the sophisticated chemical and physical properties of Sn-based perovskites, theoretical calculations based on density functional theory (DFT) provide a useful insight into the interplay between absorbers and CTLs. Here, FASnI₃ is chosen as a benchmark material. We thoroughly investigate the influence of its surface termination on structural and electronic properties when interfacing with organic C₆₀ (100) and inorganic SnO₂ (100) and (110), including the intermediate work function calculations on the free-standing slabs. Based on the theoretical methodology developed in our team⁷, we have evidenced the proportionality between work function shifts and surface dipoles, making the optimization of interfacial charge transport possible by surface dipole tuning. Our findings on the charge transport properties of the two targeted CTLs, contribute to analyzing promising alternatives as CTLs for Pb-free perovskites thanks to the surface and interface engineering.

References:

[1] Li, J.; Duan, J.; Yang, X.; Duan, Y.; Yang, P.; Tang, Q. Review on Recent Progress of Lead-Free Halide Perovskites in Optoelectronic Applications. Nano Energy 2021, 80, 105526.

[2] Dong, Q.; Fang, Y.; Shao, Y.; Mulligan, P.; Qiu, J.; Cao, L.; Huang, J. Electron-Hole Diffusion Lengths>175 Μm in Solution-Grown CH3NH3PbI3 Single Crystals. Science 2015, 347 (peng), 967–970

[3] Jiang, T.; Chen, Z.; Chen, X.; Liu, T.; Chen, X.; Sha, W. E. I.; Zhu, H.; Yang, Y. (Michael). Realizing High Efficiency over 20% of Low‐Bandgap Pb–Sn‐Alloyed Perovskite Solar Cells by In Situ Reduction of Sn 4+. Sol. RRL 2020, 4 (3), 1900467

[4] Lin, R.; Xiao, K.; Qin, Z.; Han, Q.; Zhang, C.; Wei, M.; Saidaminov, M. I.; Gao, Y.; Xu, J.; Xiao, M.; Li, A.; Zhu, J.; Sargent, E. H.; Tan, H. Monolithic All-Perovskite Tandem Solar Cells with 24.8% Efficiency Exploiting Comproportionation to Suppress Sn(Ii) Oxidation in Precursor Ink. Nat Energy 2019, 4 (10), 864–873

[5] Shao, S.; Loi, M. A. The Role of the Interfaces in Perovskite Solar Cells. Adv. Mater. Interfaces 2020, 7 (1), 1901469

[6] Lin, R.; Xu, J.; Wei, M.; Wang, Y.; Qin, Z.; Liu, Z.; Wu, J.; Xiao, K.; Chen, B.; Park, S. M.; Chen, G.; Atapattu, H. R.; Graham, K. R.; Xu, J.; Zhu, J.; Li, L.; Zhang, C.; Sargent, E. H.; Tan, H. All-Perovskite Tandem Solar Cells with Improved Grain Surface Passivation. Nature 2022, 603 (7899), 73–78

[7] Traoré, B.; Basera, P.; Ramadan, A. J.; Snaith, H. J.; Katan, C.; Even, J. A Theoretical Framework for Microscopic Surface and Interface Dipoles, Work Functions, and Valence Band Alignments in 2D and 3D Halide Perovskite Heterostructures. ACS Energy Lett. 2022, 7 (1), 349–357

Acknowledgements:

This DROP-IT project⁸ has received funding from the European Union’s Horizon 2020 research and innovation Program under the grant agreement N^o 862656. The information and views set out in the abstracts and presentations are those of the authors and do not necessarily reflect the official opinion of the European Union. Neither the European Union institutions and bodies nor any person acting on their behalf may be held responsible for the use which may be made of the information contained herein.

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