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Unraveling the varied nature and roles of defects in hybrid halide perovskites with time-resolved photoemission electron microscopy

DOI: 10.1039/D1EE02055B DOI Help

Authors: Sofiia Kosar (Okinawa Institute of Science and Technology Graduate University) , Andrew J. Winchester (Okinawa Institute of Science and Technology Graduate University) , Tiarnan A. S. Doherty (University of Cambridge) , Stuart Macpherson (University of Cambridge) , Christopher E. Petoukhoff (Okinawa Institute of Science and Technology Graduate University) , Kyle Frohna (University of Cambridge) , Miguel Anaya (University of Cambridge) , Nicholas S. Chan (Okinawa Institute of Science and Technology Graduate University) , Julien Madéo (Okinawa Institute of Science and Technology Graduate University) , Michael K. L. Man (Okinawa Institute of Science and Technology Graduate University) , Samuel D. Stranks (University of Cambridge) , Keshav M. Dani (Okinawa Institute of Science and Technology Graduate University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Energy & Environmental Science , VOL 3

State: Published (Approved)
Published: September 2021
Diamond Proposal Number(s): 19023

Open Access Open Access

Abstract: With rapidly growing photoconversion efficiencies, hybrid perovskite solar cells have emerged as promising contenders for next generation, low-cost photovoltaic technologies. Yet, the presence of nanoscale defect clusters, that form during the fabrication process, remains critical to overall device operation, including efficiency and long-term stability. To successfully deploy hybrid perovskites, we must understand the nature of the different types of defects, assess their potentially varied roles in device performance, and understand how they respond to passivation strategies. Here, by correlating photoemission and synchrotron-based scanning probe X-ray microscopies, we unveil three different types of defect clusters in state-of-the-art triple cation mixed halide perovskite thin films. Incorporating ultrafast time-resolution into our photoemission measurements, we show that defect clusters originating at grain boundaries are the most detrimental for photocarrier trapping, while lead iodide defect clusters are relatively benign. Hexagonal polytype defect clusters are only mildly detrimental individually, but can have a significant impact overall if abundant in occurrence. We also show that passivating defects with oxygen in the presence of light, a previously used approach to improve efficiency, has a varied impact on the different types of defects. Even with just mild oxygen treatment, the grain boundary defects are completely healed, while the lead iodide defects begin to show signs of chemical alteration. Our findings highlight the need for multi-pronged strategies tailored to selectively address the detrimental impact of the different defect types in hybrid perovskite solar cells.

Diamond Keywords: Photovoltaics; Semiconductors

Subject Areas: Materials, Chemistry, Energy

Instruments: I14-Hard X-ray Nanoprobe

Added On: 22/09/2021 09:52


Discipline Tags:

Surfaces Earth Sciences & Environment Sustainable Energy Systems Energy Physics Climate Change Physical Chemistry Energy Materials Chemistry Materials Science interfaces and thin films Perovskites Metallurgy

Technical Tags:

Microscopy Electron Microscopy (EM) PhotoEmmission Electron Microscopy (PEEM)