Title: Optical-Vibrational Properties of the Cs₂ SnX₆ (X = Cl, Br, I) Defect Perovskites and Hole-Transport Efficiency in Dye-Sensitized Solar Cells

Abstract

We report the vibrational and optical properties of the ‘defect’ perovskites Cs₂SnX₆ (X = Cl, Br, I) as well as their use as hole-transporting materials (HTMs) in solar cells. All three air-stable compounds were characterized using powder X-ray diffraction and Rietveld refinement. Far-IR reflectance, Raman, and UV–vis spectroscopy as well as electronic band structure calculations show that the compounds are direct band gap semiconductors with a pronounced effect of the halogen atom on the size of the energy gap and the vibrational frequencies. Scanning electron microscopy and atomic force microscopy confirmed that the morphology of the perovskite films deposited from $N,N$-dimethylformamide solutions on TiO₂ substrates also strongly depends on the chemical composition of the materials. The Cs₂SnX₆ perovskites were introduced as hole-transporting materials in dye-sensitized solar cells, based on mesoporous titania electrodes sensitized with various organic and metal–organic dyes. The solar cells based on Cs₂SnI₆ HTM and the Z907 dye performed best with a maximum power conversion efficiency of 4.23% at 1 sun illumination. The higher performance of Cs₂SnI₆ is attributed to efficient charge transport in the bulk material and hole extraction at the perovskite-Pt interface, as evidenced by electrochemical impedance spectroscopy.

Authors:

Kaltzoglou, Andreas ^[1]; Antoniadou, Maria ^[1]; Kontos, Athanassios G. ^[1]; Stoumpos, Constantinos C. ^[2]; Perganti, Dorothea ^[1]; Siranidi, Eirini ^[1]; Raptis, Vasilios ^[1]; Trohidou, Kalliopi ^[1]; Psycharis, Vassilis ^[1]; Kanatzidis, Mercouri G. ^[2]; Falaras, Polycarpos ^[1]

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+ Show Author Affiliations

1. National Center for Scientific Research, Athens (Greece). Inst. of Nanoscience and Nanotechnology
2. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry

Publication Date:

Thu May 26 00:00:00 EDT 2016

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Argonne-Northwestern Solar Energy Research Center (ANSER)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1388195

Grant/Contract Number:  

SC0001059

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 120; Journal Issue: 22; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (homogeneous); catalysis (heterogeneous); solar (photovoltaic); solar (fuels); photosynthesis (natural and artificial); bio-inspired; hydrogen and fuel cells; electrodes - solar; defects; charge transport; spin dynamics; membrane; materials and chemistry by design; optics; synthesis (novel materials); synthesis (self-assembly)