Dataset Information

Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.

ABSTRACT: The highest reported efficiencies of metal halide perovskite (MHP) solar cells are all based on mixed perovskites, such as (FA,MA,Cs)Pb(I1-x Br x )3. Despite demonstrated structural changes induced by light soaking, it is unclear how the charge carrier dynamics are affected across this entire material family. Here, various (FA,MA,Cs)Pb(I1-x Br x )3 perovskite films are light-soaked in nitrogen, and changes in optoelectronic properties are investigated through time-resolved microwave conductivity (TRMC) and optical and structural techniques. To fit the TRMC decay kinetics obtained for pristine (FA,MA,Cs)Pb(I1-x Br x )3 for various excitation densities, additional shallow states have to be included, which are not required for describing TRMC traces of single-cation MHPs. These shallow states can, independently of x, be removed by light soaking, which leads to a reduction in the imbalance between the diffusional motion of electrons and holes. We interpret the shallow states as a result of initially well-intermixed halide distributions, which upon light soaking segregate into domains with distinct band gaps.

SUBMITTER: Guo D

PROVIDER: S-EPMC6792222 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.

Guo Dengyang D Andaji Garmaroudi Zahra Z Abdi-Jalebi Mojtaba M Stranks Samuel D SD Savenije Tom J TJ

ACS energy letters 20190905 10

The highest reported efficiencies of metal halide perovskite (MHP) solar cells are all based on mixed perovskites, such as (FA,MA,Cs)Pb(I1-x Br x )3. Despite demonstrated structural changes induced by light soaking, it is unclear how the charge carrier dynamics are affected across this entire material family. Here, various (FA,MA,Cs)Pb(I1-x Br x )3 perovskite films are light-soaked in nitrogen, and chan ...[more]

PMID: 31633033

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Project description:Despite the ideal performance demonstrated by mixed perovskite materials when used as active layers in photovoltaic devices, the factor which still hampers their use in real life remains the poor stability of their physico-chemical and functional properties when submitted to prolonged permanence in atmosphere, exposure to light and/or to moderately high temperature. We used high resolution photoelectron spectroscopy to compare the chemical state of triple cation, double halide Csx(FA0.83MA0.17)(1-x)Pb(I0.83Br0.17)3 perovskite thin films being freshly deposited or kept for one month in the dark or in the light in environmental conditions. Important deviations from the nominal composition were found in the samples aged in the dark, which, however, did not show evident signs of oxidation and basically preserved their own electronic structures. Ageing in the light determined a dramatic material deterioration with heavily perturbed chemical composition also due to reactions of the perovskite components with surface contaminants, promoted by the exposure to visible radiation. We also investigated the implications that 2D MXene flakes, recently identified as effective perovskite additive to improve solar cell efficiency, might have on the labile resilience of the material to external agents. Our results exclude any deleterious MXene influence on the perovskite stability and, actually, might evidence a mild stabilizing effect for the fresh samples, which, if doped, exhibited a lower deviation from the expected stoichiometry with respect to the undoped sample. The evolution of the undoped perovskites under thermal stress was studied by heating the samples in UHV while monitoring in real time, simultaneously, the behaviour of four representative material elements. Moreover, we could reveal the occurrence of fast changes induced in the fresh material by the photon beam as well as the enhanced decomposition triggered by the concurrent X-ray irradiation and thermal heating.

Dataset Information

Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.

Publications

Reversible Removal of Intermixed Shallow States by Light Soaking in Multication Mixed Halide Perovskite Films.

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