Solution Processable Direct Bandgap Copper‐Silver‐Bismuth Iodide Photovoltaics: Compositional Control of Dimensionality and Optoelectronic Properties. Issue 32 (17th July 2022)

• Record Type: Journal Article
• Authors: Pai, Narendra; Chatti, Manjunath; Fürer, Sebastian O.; Scully, Andrew D.; Raga, Sonia R.; Rai, Nitish; Tan, Boer; Chesman, Anthony S. R.; Xu, Zhou; Rietwyk, Kevin J.; Reddy, Saripally Sudhaker; Hora, Yvonne; Sepalage, Gaveshana A.; Glück, Nadja; Lira‐Cantú, Monica; Bach, Udo; Simonov, Alexandr N.
• Is Part Of: Advanced energy materials. Volume 12:Issue 32(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-17
• Subjects: CuAgBiI 5 -- Cu 2AgBiI 6 -- solar cells -- thin film; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202201482
• Languages: English
• ISSNs: 1614-6832

Abstract

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 Cu x AgBiI4+ 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 Cu2 AgBiI6 at x = 2, and a mix of the two at 1 < x < 2 is demonstrated. Despite lower structural dimensionality, Cu2 AgBiI6 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 Cu2 AgBiI6 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 Cu2 AgBiI6 layer thickness to match the carrier diffusion length of ≈40–50 nm. Nonencapsulated Cu2 AgBiI6 solar cells display storage stability over 240 days. Abstract : Thin films of Cu x AgBiI4+ x with compositionally controlled phase dimensionality and light‐harvesting properties are synthesized via a simple yet effective hot‐casting method. Using these materials as active layers in thin‐film solar cells enables power‐conversion efficiencies under 1 sun of 2.4% and high environmental stability on a month's timescale.