Solution Processable Direct Bandgap Copper-Silver-Bismuth Iodide Photovoltaics: Compositional Control of Dimensionality and Optoelectronic Properties

Narendra Pai, Manjunath Chatti, Sebastian O. Fürer, Andrew D. Scully, Sonia R. Raga, Nitish Rai, Boer Tan, Anthony S.R. Chesman, Zhou Xu, Kevin J. Rietwyk, Saripally Sudhaker Reddy, Yvonne Hora, Gaveshana A. Sepalage, Nadja Glück, Monica Lira-Cantú, Udo Bach, Alexandr N. Simonov

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The search for lead-free alternatives to lead-halide perovskite photovoltaic materials resulted in the discovery of copper(I)-silver(I)-bismuth(III) halides exhibiting promising properties for optoelectronic applications. The present work demonstrates a solution-based synthesis of uniform CuxAgBiI4+x thin films and scrutinizes the effects of x on the phase composition, dimensionality, optoelectronic properties, and photovoltaic performance. Formation of pure 3D CuAgBiI5 at x = 1, 2D Cu2AgBiI6 at x = 2, and a mix of the two at 1 < x < 2 is demonstrated. Despite lower structural dimensionality, Cu2AgBiI6 has broader optical absorption with a direct bandgap of 1.89 ± 0.05 eV, a valence band level at -5.25 eV, improved carrier lifetime, and higher recombination resistance as compared to CuAgBiI5. These differences are mirrored in the power conversion efficiencies of the CuAgBiI5 and Cu2AgBiI6 solar cells under 1 sun of 1.01 ± 0.06% and 2.39 ± 0.05%, respectively. The latter value is the highest reported for this class of materials owing to the favorable film morphology provided by the hot-casting method. Future performance improvements might emerge from the optimization of the Cu2AgBiI6 layer thickness to match the carrier diffusion length of ≈40–50 nm. Nonencapsulated Cu2AgBiI6 solar cells display storage stability over 240 days.

Original languageEnglish
Article number2201482
JournalAdvanced Energy Materials
Volume12
Issue number32
DOIs
StatePublished - 25 Aug 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.

Keywords

  • Cu AgBiI
  • CuAgBiI
  • solar cells
  • thin film

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