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AgBiI 4 as a Lead-Free Solar Absorber with Potential Application in Photovoltaics

DOI: 10.1021/acs.chemmater.6b04135 DOI Help

Authors: Harry C. Sansom (University of Liverpool) , George F. S. Whitehead (University of Liverpool) , Matthew S. Dyer (University of Liverpool) , Marco Zanella (University of Liverpool) , Troy D. Manning (University of Liverpool) , Michael J. Pitcher (University of Liverpool) , Thomas J. Whittles (University of Liverpool) , Vinod R. Dhanak (University of Liverpool) , Jonathan Alaria (University of Liverpool) , John B. Claridge (University of Liverpool) , Matthew J. Rosseinsky (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials

State: Published (Approved)
Published: January 2017
Diamond Proposal Number(s): 12336

Open Access Open Access

Abstract: AgBiI4 powder, crystals and polycrystalline films were synthesized by sealed tube solid state reactions, chemical vapor transport (CVT) and solution processing, respectively, and their structural, optical and electronic properties are reported. The structure of AgBiI4 is based unambiguously upon a cubic close packed iodide sub-lattice, but it presents an unusual crystallographic problem: we show that the reported structure, a cubic defect-spinel, cannot be distinguished from a metrically cubic layered structure analogous to CdCl2 using either powder or single crystal X-ray crystallography. In addition, we demonstrate the existence a non-cubic CdCl2-type polymorph by isolation of non-twinned single crystals. The indirect optical band gap of AgBiI4 is measured to be 1.63(1) eV, comparable to the indirect band gap of 1.69(1) eV measured for BiI3 and smaller than that reported for other bismuth halides, suggesting that structures with a close-packed iodide sub-lattice may give narrower band gaps than those with perovskite structures. Band edge states closely resemble those of BiI3, however the p-type nature of AgBiI4 with low carrier concentration is more similar to MAPbI3 than the n-type BiI3. AgBiI4 shows good stability toward the AM1.5 solar spectrum when kept in a sealed environment, and is thermally stable below 90 °C.

Subject Areas: Chemistry, Materials

Instruments: I11-High Resolution Powder Diffraction