Recent Progress in Fabrication of Antimony/Bismuth Chalcohalides for Lead-Free Solar Cell Applications

Abstract

Despite their comparable performance to commercial solar systems, lead-based perovskite (Pb-perovskite) solar cells exhibit limitations including Pb toxicity and instability for industrial applications. To address these issues, two types of Pb-free materials have been proposed as alternatives to Pb-perovskite: perovskite-based and non-perovskite-based materials. In this review, we summarize the recent progress on solar cells based on antimony/bismuth (Sb/Bi) chalcohalides, representing Sb/Bi non-perovskite semiconductors containing chalcogenides and halides. Two types of ternary and quaternary chalcohalides are described, with their classification predicated on the fabrication method. We also highlight their utility as interfacial layers for improving other solar cells. This review provides clues for improving the performances of devices and design of multifunctional solar systems.

Keywords: antimony chalcohalides; bismuth chalcohalides; solar cells.

Figure 1

Energy band diagram of typical Sb/Bi chalcohalides. The SbSI, Sb_0.67Bi_0.33SI, BiSI, Pb₂SbS₂I₃, and Sn₂SbS₂I₃ energy levels were obtained from [23,38,47,54] and [24], respectively. For comparison, the energy levels for typical conducting oxides (F-doped SnO₂ (FTO) and In-doped SnO₂ (ITO)), the electron transporting layer (ETL), and hole transporting layer (HTL) are included. P3HT, PCPDTBT, and F8 denote poly(3-hexylthiophene), poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)], and poly(9,9-di-n-octylfluorenyl-2,7-diyl), respectively.

Figure 2

Images and plots characterizing Se-doped BiSI films fabricated by spray pyrolysis at varied Se doping levels including: (a) surface morphologies; (b) absorption and direct Eg graph. Adapted with permission from J. Phys. Chem. C 2012, 116, 24878–24886. Copyright 2012 American Chemical Society [40].

Figure 3

Images and plots for Sb/Bi chalcohalides fabricated by the one-step method based on the spin-coating technique showing: (a) structure and surface morphology; (b) photovoltaic device performance for BiSI films fabricated by Tiwari et al. [46]. Adapted with permission from ACS Appl. Energy Mater. 2019, 2, 3878–3885. Copyright 2019 American Chemical Society [46]. (c) Surface morphology image of Sb₂S₃-containing SbSI; (d–f) the device performance. Adapted with permission from Chem. Mater. 2020, 32, 6416–6424. Copyright 2020 American Chemical Society [51].

Figure 4

(a) Schematic illustration of the two-step method for SbSI fabrication. Adapted from [38], with permission from John Wiley and Sons, 2017; (b) Structure, absorption, and X-ray photoelectron spectroscopy properties of the Sb_0.67Bi_0.33SI. Adapted from [23], with permission from John Wiley and Sons, 2019; (c) Schematic illustration of the two processes utilized in step 2 of the SbSI fabrication. Adapted from [65], with permission from John Wiley and Sons, 2019.

Figure 5

(a) Schematic illustration of the two-step method for the SbSI fabrication. Effects of Sb:S ratio on the morphology after: (b) step 1; (c,d) step 2. Adapted under the terms and conditions of the CC BY license [45], copyright 2018, The Authors. Adapted from [45], from AIP Publishing, 2018. (e) Schematic diagram of the two-step method for BiSI fabrication. Diagrams showing the (f) structure and (g) absorption properties of the samples fabricated after step 1 and 2. Adapted under the terms and conditions of the CC BY license [47], copyright 2019, The Authors. Adapted from [47], from MDPI AG, 2019.

Figure 6

BiSI nanorods array fabrication from Xiong et al. [49] showing: (a) a schematic diagram of the BiSI nanorod arrays fabrication procedure and (b) a typical current density–voltage curve of n ITO/CuSCN/BiSI/W device. Adapted with permission from ACS Sustainable Chem. Eng. 2020, 8, 13488–13496. Copyright 2020 American Chemical Society [49].

Figure 7

(a) Structures of the BiSBr_1−xI_x obtained from BiOBr_1−xI_x under H₂S gas at 150 °C. Adapted under the terms and conditions of the CC BY license [41], copyright 2016, the authors. Adapted from [41], from Springer Nature, 2016. Structure and device performance for the Bi-S-I compounds synthesized by the solvothermal method: (b) Plot showing the effects of the CH₄N₂S/BiI₃/MAI molar ratio including (1) 1:2:3, (2) 2:2:3, (3) 3:2:3, (4) 4:2:3, and (5) 8:2:3 on structures. (c) Schematic diagram and J–V curves of Bi₁₃S₁₈I₂ solar cells. Adapted from [53], with permission from Royal Society of Chemistry, 2020.