Surfaces, interfaces and doping of metal halide perovskites: fundamental issues and opportunities
Abstract
In the standard configurations of metal halide perovskite (MHP) solar cell, the active layer follows a p-i-n or n-i-p electronic structure designed to enhance the extraction of photo-induced charge carriers. The control of the Fermi level (EF) position across the film, between electron and hole transport layers, is therefore of paramount importance. Direct, spacially localized and stable doping in metal halide
perovskites being still elusive, the design of n-i-p and p-i-n structures so far relies predominantly on surface and interface doping of the perovskite, as well as on the control of the work function of the substrate and transport layers on which, or between which, the absorber is being placed. How is that possible with MHP films? The ability to control the EF position through interface doping, akin to what is possible with organic semiconductors and in contrast with standard inorganic counterparts, is owed to the absence of significant densities of deep Fermi level pinning surface and interface states in the energy gap of MHPs.[1] This talk provides a review of work on (i) the electronic structure of MHP surfaces, and interfaces with both organic and inorganic electron and hole transport layers (ETL, HTL);2 the use of molecular oxidants and reductants deposited on perovskite surfaces and the impact of these dopants on energy level alignment with substrate and charge transport layers, and ultimately, on devices;5 bulk doping of the perovskite layer with molecular dopants;[6] and, time permitting, mitigation of MHP degradation via thiol molecules surface treatment.[7]
[1] Philip Schulz et al., Adv. Mat. Int. 2, 1400532 (2015); Arava Zohar et al, ACS Energy Le[. 4, 1 (2019); David Cahen et al. Adv. Mater. 36, 2407098 (2024)
[2] James Endres et al, J. Phys. Chem. Le[. 7, 2722 (2016); Philip Schulz et al., Energ. & Envir. Sci. 7, 1377 (2014)
[3] Nakita K. Noel et al., Energ. & Envir. Sci. 12, 3063 (2019)
[4] Julie Euvrard et al., Mater. Adv. 2, 2956 (2021)
[5] Junnan Hu et al., Adv. Mater., 35, 2303373 (2023)
About the speaker
Antoine Kahn is professor in engineering and applied science at Princeton. He is a fellow of the American Physical Society and the American Vacuum Society. His research programs center on the electronic, chemical, structural and electrical properties of materials relevant to thin-film electronic devices. His interests span a range of semiconductor materials (elemental and compounds), but his current work focuses specifically on organic molecular and polymer semiconductors, dielectrics developed for applications in organic and molecular electronics, and the hot new class of optoelectronic materials called hybrid metal halide perovskites (MHP). His group is particularly interested in engineering materials and interfaces that improve the performance of devices, with application to organic light-emitting diodes (OLEDs), field effect transistors (OFETs), organic photovoltaic cells (OPVs), MHP-based solar cells and light emitting diodes, and other thin-film devices applicable to large-area, flexible electronics.
We invite you to follow the seminar online in case you cannot make it in person.
- Meeting number: 2780 953 3957
- Meeting password: MHt33MrWNU6