Controlling charge, spin and light in Lead-Halide Inspired Hybrid Semiconductors
Matthew Beard a b
a National Renewable Energy Laboratory
b Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE)
Proceedings of Applied Light-Matter Interactions in Perovskite Semiconductors 2021 (ALMIPS2021)
Online, Spain, 2021 October 5th - 7th
Organizers: Rafael Sánchez Sánchez and Miguel Anaya
Invited Speaker, Matthew Beard, presentation 011
DOI: https://doi.org/10.29363/nanoge.almips.2021.011
Publication date: 23rd September 2021

In this presentation I will discuss our studies of controlling the charge carrier dynamics, light/matter interactions, and spin populations in these novel hybrid systems. In one effort we are exploring the use of novel organic hybrid systems at and near interfaces to control the carrier dynamics and reduce surface recombination but also to protect grain boundary surfaces from degradation. With respect to controlling spins we have recently studied and developed a novel class of chiral hybrid semiconductors based upon layered metal-halide perovskite 2D Ruddlesden-Popper type structures. These systems exhibit chiral induced spin selectivity whereby only one spin sense can transport across the film and the other spin sense is blocked. From these systems we can achieve a high degree of spin current polarization and injection when used as a contact layer. We have developed novel spin-based LEDs using mixed NCs as the light emitting layer that promotes light emission at a highly spin-polarized interface. The LED spin-polarization is limited by spin-depolarization within the MHP NCs. In a separate effort we have explored the use of chiral copper-halide hybrid systems for circular light polarized detection. Chiral based copper-halide systems combined with highly conductive carbon nanotube networks can be employed to detect circular polarized light with the use of polarizers. Our chiral heterostructure shows high photoresponsivity of 452 A/W, a competitive anisotropy factor of up to 21%, a current response in microamperes, and low working voltage down to 0.01 V. These results demonstrate that the emergent properties of organic−inorganic hybrid systems offer unique opportunities in controlling light, charge and spin..

In another effort we are studying NCs of metal-halide perovskite semiconductors as photocatalysts for light-driven chemical transformations. For photocatalytic applications these NCs are highly photoactive, support charge-separation and migration and have low surface defect densities. We have studied their use as photo-redox systems to drive C-C bond formation reactions. Recently we are taking advantage of the ease of cation substitution at the surface of the NCs to develop a photocatalyst that undergoes multiple sequential inner-sphere photo-oxidation events. A diamine substrate is bound to surface Cu+1 cations, which attract holes from the valence band of the NCs and promotes sequential oxidization of the bound diamine to form a N-N heterocycle.

This work was supported as part of the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE) an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science within the U.S. Department of Energy

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