High Photon‐to‐Current Conversion in Solar Cells Based on Light‐Absorbing Silver Bismuth Iodide

• Published in: ChemSusChem Vol. 10; no. 12; pp. 2592 - 2596
• Main Authors: Zhu, Huimin, Pan, Mingao, Johansson, Malin B., Johansson, Erik M. J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 22.06.2017; John Wiley and Sons Inc
• Subjects: Absorption spectra; Absorption, Radiation; Bismuth; Bismuth - chemistry; Communication; Communications; Conducting polymers; Crystal structure; Devices; Electric Conductivity; Electric Power Supplies; Electromagnetic absorption; Energy conversion efficiency; Energy gap; Halides; Iodides; Iodides - chemistry; Lead free; Models, Molecular; Molecular Conformation; perovskite solar cells; Photoelectric effect; Photoelectric emission; Photons; Photovoltaic cells; power conversion efficiency; Quantum efficiency; Silver; silver bismuth iodide; Silver Compounds - chemistry; Solar cells; Solar Energy; space group; Titanium - chemistry; Titanium oxides; Transport; X-ray diffraction; power conversion efficiency; silver bismuth iodide; space group; x-ray diffraction; perovskite solar cells
• ISSN: 1864-5631; 1864-564X; 1864-564X
• DOI: 10.1002/cssc.201700634

Here, a lead‐free silver bismuth iodide (AgI/BiI3) with a crystal structure with space group R3‾ m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from solution on top of TiO2 and the conducting polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as a hole‐transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth‐halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi2I7, and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X‐ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾ m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal‐halides efficient in solar cells and points out new directions for further exploration of lead‐free metal‐halide solar cells. Minus the lead: Devices based on silver bismuth iodide deposited from solution on top of TiO2 and the conducting polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as a hole‐transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %.