Efficient and Stable Antimony Selenoiodide Solar Cells

Abstract

Although antimony selenoiodide (SbSeI) exhibits a suitable bandgap as well as interesting physicochemical properties, it has not been applied to solar cells. Here the fabrication of SbSeI solar cells is reported for the first time using multiple spin-coating cycles of SbI₃ solutions on Sb₂Se₃ thin layer, which is formed by thermal decomposition after depositing a single-source precursor solution. The performance exhibits a short-circuit current density of 14.8 mA cm^-2, an open-circuit voltage of 473.0 mV, and a fill factor of 58.7%, yielding a power conversion efficiency (PCE) of 4.1% under standard air mass 1.5 global (AM 1.5 G, 100 mW cm^-2). The cells retain ≈90.0% of the initial PCE even after illuminating under AM 1.5G (100 mW cm^-2) for 2321 min. Here, a new approach is provided for combining selenide and iodide as anions, to fabricate highly efficient, highly stable, green, and low-cost solar cells.

Keywords: SbSeI; chalcohalides; lead‐free perovskite materials; solar cells.

Figure 1

Confirmation of SbSeI. a) Schematic diagrams of crystal structure of SbSeI in general, side, and top views. b,c) XRD patterns at ranges of 10°–60°, 18°–22°, and 28°–32.5°, and d) UV–vis absorption spectrum of glass/mp‐TiO₂/SbSeI. Standard SbSeI (JCPDS No. 76‐1354) structure file is shown as the red column in (c). Main peak of TiO₂ at 25.3° is marked as “T” in (c). Insets in (d) show the corresponding Tauc plot and a photograph of the glass/mp‐TiO₂/SbSeI. e) Low magnification and f) high magnification HR‐TEM of SbSeI on mp‐TiO₂. g) HAADF–STEM, and corresponding EDX mapping images of SbSeI on mp‐TiO₂.

Figure 2

Distribution and energy level. a) Surface SEM image of glass/mp‐TiO₂/SbSeI. b) Cross‐sectional SEM image of FTO/BL/mp‐TiO₂/SbSeI/HTM(L)/Au solar cell. c) EDX line data scanned from the top to bottom in mp‐TiO₂/SbSeI/HTM(L) layer in (b). d) EDX mapping data acquired from yellow rectangle in (b). e) Secondary electron cut‐off region of He I UPS spectra and XPS valence level spectrum for FTO/mp‐TiO₂/SbSeI. f) Energy levels of the functional materials employed in FTO/BL/mp‐TiO₂/SbSeI/HTL/Au solar cells.

Figure 3

Effect of SbSeI loading amount on the device performance. a) J–V curves under standard illumination conditions (100 mW cm⁻²) of AM 1.5 G and b) IPCE spectra of SbSeI solar cells fabricated through 8, 10, and 12 spin‐coating cycles and thermal decomposition. c) UV–vis absorption spectra of the glass/mp‐TiO₂/SbSeI prepared by 8, 10, and 12 cycles of spin‐coating and thermal decomposition processes. d) Nyquist plots under dark condition. e,f) Dependence of dark current and photo current on temperature of SbSeI devices fabricated through 10 and 12 spin‐coating cycles and thermal decomposition. The inset in (d) shows an equivalent circuit used to fit impedance curves. g) Schematic diagrams of light‐harvesting and charge‐transfer processes in SbSeI solar cells fabricated through 8, 10, and 12 spin‐coating cycles and thermal decomposition.

Figure 4

The best‐performing cell. a) J–V characteristic under standard illumination conditions (AM 1.5 G, 100 mW cm⁻²) of SbSeI solar cell and b) corresponding external quantum efficiency (EQE) spectrum. The device performance parameters are listed in the inset. c) Stabilized power output of SbSeI solar cell by maintaining the voltage at maximum power point (0.376 V). d) Histogram of device efficiencies from 49 individual cells.

Figure 5

Long‐term stability. Changes in normalized device performance of unencapsulated SbSeI solar cells as storage time increases: a,b) in ambient atmosphere (≈80% humidity) and in the dark at room temperature, c,d) measured at 85 °C in air (<30% relative humidity), and e) under standard AM 1.5G illumination using a Xenon lamp including UV light.