Nanoscale Chemical Landscape Dominates Optoelectronic Response in Alloyed Halide Perovskites

Kyle Frohna^a, Miguel Anaya^a^,^b, Stuart Macpherson^a, Jooyoung Sung^a, Tiarnan A.S. Doherty^a^,^b, Yu-Hsien Chiang^a, Andrew J. Winchester^c, Kieran W.P. Orr^a^,^b, Julia E. Parker^d, Paul D. Quinn^d, Keshav M. Dani^c, Akshay Rao^a, Samuel D. Stranks^a^,^b

^aCavendish Laboratory, University of Cambridge, Cambridge, UK

^bDepartment of Chemical Engineering and Biotechnology, University of Cambridge; Cambridge, UK

^cFemtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904 0495, Japan

^dDiamond Light Source, Didcot OX11 0DE, UK.

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)

València, Spain, 2022 May 19th - 25th

Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson

Oral, Kyle Frohna, presentation 081
DOI: https://doi.org/10.29363/nanoge.hopv.2022.081
Publication date: 20th April 2022

Halide perovskites perform remarkably in optoelectronic devices including tandem photovoltaics^1,2. However, this exceptional performance is striking given that perovskites exhibit deep charge carrier traps and spatial compositional and structural heterogeneity^3-5, all of which would be expected to negatively impact performance. In this presentation, I will discuss how we resolve this long-standing paradox by providing a global visualisation of the nanoscale chemical, structural and optoelectronic landscape in halide perovskite devices⁶. The development of a new suite of correlative, multimodal microscopy measurements combining quantitative optical spectroscopic techniques and synchrotron nanoprobe measurements which enabled us to understand this complex landscape will be described. I will show that compositional disorder dominates the optoelectronic response, while nanoscale strain variations, even of large magnitude (~1 %) which would be deleterious to performance in III-V devices⁷, have only a weak influence. Nanoscale compositional gradients drive carrier funneling onto local regions associated with low electronic disorder. These energetic funnels draw carrier recombination away from trap clusters associated with high electronic disorder and leading to high local photoluminescence quantum efficiency. These measurements reveal a global picture of the competitive nanoscale landscape, which endows enhanced defect tolerance in devices through spatial chemical disorder that outcompetes both electronic and structural disorder.

References:

[1] Al-Ashouri, A. et al. Monolithic perovskite/silicon tandem solar cell with >29% efficiency by enhanced hole extraction. Science 370, 1300, 2020

[2] Xu, J. et al. Triple-halide wide–band gap perovskites with suppressed phase segregation for efficient tandems. Science 367, 1097, 2020

[3] Doherty, T. A. S. et al. Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites. Nature 580, 360-366, 2020

[4] Correa-Baena, J.-P. et al. Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites. Science 363, 627, 2019

[5] Feldmann, S. et al. Photodoping through local charge carrier accumulation in alloyed hybrid perovskites for highly efficient luminescence. Nat. Photonics 14, 123-128, 2020

[6] Frohna, K. et al. Nanoscale chemical heterogeneity dominates the optoelectronic response of alloyed perovskite solar cells. Nat. Nanotechnol. 17, 190-196, 2022

[7] Bioud, Y. A. et al. Uprooting defects to enable high-performance III–V optoelectronic devices on silicon. Nat. Commun. 10, 4322, 2019

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