Ionic Accumulation as a Diagnostic Tool in Perovskite Solar Cells: Characterizing Band Alignment with Rapid Voltage Pulses
Advanced Materials, vol. 35, pp. e2302146
Abstract
Despite record-breaking devices, interfaces in perovskite solar cells are still poorly understood, inhibiting further progress. Their mixed ionic-electronic nature results in compositional variations at the interfaces, depending on the history of externally applied biases. This makes it difficult to measure the band energy alignment of charge extraction layers accurately. As a result, the field often resorts to a trial-and-error process to optimize these interfaces. Current approaches are typically carried out in a vacuum and on incomplete cells, hence values may not reflect those found in working devices. To address this, a pulsed measurement technique characterizing the electrostatic potential energy drop across the perovskite layer in a functioning device is developed. This method reconstructs the current-voltage (JV) curve for a range of stabilization biases, holding the ion distribution "static" during subsequent rapid voltage pulses. Two different regimes are observed: at low biases, the reconstructed JV curve is "s-shaped", whereas, at high biases, typical diode-shaped curves are returned. Using drift-diffusion simulations, it is demonstrated that the intersection of the two regimes reflects the band offsets at the interfaces. This approach effectively allows measurements of interfacial energy level alignment in a complete device under illumination and without the need for expensive vacuum equipment.
Authors 14
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Affiliation as printed
School of Mathematics Statistics and Physics Newcastle University Herschel Building Newcastle upon Tyne NE1 7RU UK
School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU United Kingdom
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Affiliation as printed
Centre for Sustainable and Circular Technologies Department of Chemistry University of Bath Claverton Down Bath BA2 7AY UK
Department of Chemistry University of Bath Claverton Down Bath BA2 7AY UK
Centre for Sustainable and Circular Technologies, Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
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Affiliation as printed
Department of Chemical Engineering 20 Research Way (Building 82) Monash University Clayton Campus Monash VIC 3800 Australia
Department of Chemical Engineering, 20 Research Way (Building 82), Monash University Clayton Campus, Monash, VIC, 3800 Australia
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Affiliation as printed
School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU United Kingdom
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Affiliation as printed
Mathematical Sciences University of Southampton Highfield Southampton SO17 1BJ UK
Mathematical Sciences University of Southampton, Highfield, Southampton, SO17 1BJ United Kingdom
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Center for NanoScience · Ludwig-Maximilians-Universität München
Affiliation as printed
Department of Chemistry and Center for NanoScience (CeNS) LMU Munich 81377 München Germany
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University of Bath · RWTH Aachen University
Affiliation as printed
Department of Physics, University of Bath Claverton Down Bath BA2 7AY UK
Institute of Physical Chemistry RWTH Aachen University 52074 Aachen Germany
Department, of Physics University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany
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Affiliation as printed
School of Mathematics Statistics and Physics Newcastle University Herschel Building Newcastle upon Tyne NE1 7RU UK
School of Mathematics, Statistics and Physics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU United Kingdom
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Affiliation as printed
School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU United Kingdom
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Affiliation as printed
School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU United Kingdom
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Affiliation as printed
Mathematical Sciences University of Southampton Highfield Southampton SO17 1BJ UK
Mathematical Sciences University of Southampton, Highfield, Southampton, SO17 1BJ United Kingdom
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Alison Walker corresponding
Affiliation as printed
Department of Physics, University of Bath Claverton Down Bath BA2 7AY UK
Department, of Physics University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
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Petra J. Cameron corresponding
Affiliation as printed
Centre for Sustainable and Circular Technologies Department of Chemistry University of Bath Claverton Down Bath BA2 7AY UK
Department of Chemistry University of Bath Claverton Down Bath BA2 7AY UK
Centre for Sustainable and Circular Technologies, Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY United Kingdom
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Pablo Docampo corresponding
Affiliation as printed
School of Chemistry University of Glasgow University P1 Glasgow G12 8QQ UK
School of Chemistry, University of Glasgow, University P1, Glasgow, G12 8QQ United Kingdom
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