Passivation approaches to eliminate non-radiative losses and inhibit ion migration in halide perovskites
Samuel D. Stranks a, Mojtaba Abdi-Jalebi a, Zahra Andaji-Garmaroudi a, Stefania Cacovich b, Camille Stavrakas a, Eline H. Hutter c, Tom J Savenije c, Giorgio Divitini b, Richard H. Friend a
a Cavendish Laboratory, University of Cambridge - UK, JJ Thomson Avenue, 9, Cambridge, United Kingdom
b University of Cambridge, Department of Materials Science and Metallurgy, UK, Cambridge, United Kingdom
c Delft University of Technology, The Netherlands, Julianalaan, 136, Delft, Netherlands
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics, Photonics and Optoelectronics (ABXPV18PEROPTO)
Perovskite Thin Film Photovoltaics (ABXPV18). 27-28 Feb
Rennes, France, 2018 February 27th - March 1st
Organizer: Jacky Even
Oral, Samuel D. Stranks, presentation 057
DOI: https://doi.org/10.29363/nanoge.abxpvperopto.2018.057
Publication date: 11th December 2017

Halide perovskites are generating enormous interest for their use in solar photovoltaic and light-emission applications. One property linking the high performance of these devices is a high radiative efficiency of the materials; indeed, a prerequisite for these devices to reach their theoretical efficiency limits is the elimination of all non-radiative decay. However, there still exists substantial parasitic non-radiative losses and ionic migration in the materials, both of which lead to performance limitations and instabilities.

Here, we will detail several new and promising passivation approaches through additives aimed at eliminating these problematic processes in triple cation (MA,FA,Cs)Pb(I0.8Br0.2)3 thin films. We find internal photoluminescence quantum efficiencies over 90% along with the removal of transient photo-induced ion migration processes. We use time-resolved microwave conductivity measurements to reveal mobilities exceeding 40 cm2/V/s. STEM-EDX measurements on film cross-sections reveal that the passivation treatments facilitate the presence of minimal halide vacancies (defects) by acting as a source of excess halide while also immobilizing the surplus halides into benign chemical products.

Our work reveals promising approaches to fabricate metal halide thin films with the highest optoelectronic quality. The work also provides further evidence that non-radiative decay and ionic motion are intimately related, generalizing the conjecture that there are common solutions to both problems.

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