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Page 2 of 13 Xia et al. Energy Mater. 2026, 6, 600022

reducing the contact barrier with the carbon electrode. This modification enables the power conversion efficiency
(PCE) of all-inorganic Sb 2 S 3 solar cells with fluorine-doped tin oxide (FTO)/CdS/Sb 2 S 3 /PbS/Carbon/Ag structures
to reach an impressive 7.00%, representing the most advanced performance level currently available and providing
new guidance for the development of high-performance and low-cost all-inorganic Sb 2 S 3 solar cells.

INTRODUCTION
In recent years, antimony-based solar cells have achieved rapid development due to their environmentally
friendly characteristics and excellent physical properties . Among them, antimony sulfide (Sb S ) has
[1,2]
2 3
gained significant attention as a promising light-absorbing material for thin-film solar cells, thanks to its
near-ideal bandgap of 1.7 eV, high visible-light absorption coefficient (> 5 × 10 cm ), low toxicity, and
4
-1
excellent environmental stability . Since Savadogo’s pioneering work on chemically deposited Sb S films
[3,4]
2 3
and photoelectrochemical cells in 1992 , substantial progress has been made . Solution-based techniques,
[5]
[6,7]
particularly chemical bath deposition (CBD) and hydrothermal synthesis, have dominated due to their low
equipment requirements and scalability. Notably, in 2025, Shen et al. achieved a record-breaking 8.26%
power conversion efficiency (PCE) by developing ethylenediaminetetraacetic acid disodium salt as an
additive to regulate the reaction kinetics for Sb S deposition . However, these efficiencies remain
[8]
2 3
significantly below the Shockley-Queisser (S-Q) limit (28.6%) . The S-Q analysis predicts maximum values
[9]
of open-circuit voltage (V ) = 1.402 V, short circuit current density (J ) = 22.5 mA/cm , and fill factor (FF) =
2
oc
sc
91%. In contrast, state-of-the-art devices (e.g., 8.26% PCE) exhibit substantially lower parameters: V = 0.707
oc
V (50.4% of limit), J = 17.91 mA/cm (79.6%), and FF = 64.81% (71.2%) . The severe deficit in V is
[8]
2
sc
oc
particularly critical, attributed primarily to interfacial recombination, inefficient carrier collection, and
intrinsic material defects. Among them, suppressing interface recombination to enhance the extraction
efficiency of electrons and holes has become an effective way to improve device performance.
Annealing, as a crucial step after the deposition of Sb S thin films, should be carried out at 300-450 °C,
2 3
which drives the transformation of the amorphous phase to the crystalline phase through thermal
rearrangement and simultaneously enhances the ion diffusion rate . However, this process faces multiple
[10]
challenges: Firstly, the essential annealing at high temperatures, aggravating the re-evaporation of sulfur and
Sb S due to their high saturated vapor pressure, leads to surface defects, film non-uniformity, and even
2 3
exposure of the underlying CdS layer, which finally disrupts the integrity of the p-n junction. Secondly,
residual oxygen reacting with antimony forms harmful Sb O secondary phases at high temperature, which
3
2
not only disrupts interface flatness and continuity but also introduces carrier recombination centers,
significantly reducing device efficiency . Thirdly, the re-crystallization of Sb S delivers a low-level position
[11]
2 3
of valence band energy which creates severe band mismatch with the back electrode. To address the above
challenges, researchers have explored the introduction of stable metal oxide buffer layers at the back interface
during annealing. For instance, a Ni/Ti co-doped MoO hole transport layer (HTL) can effectively extract
2
holes from the metal halide perovskite layer, achieving a PCE of 18.1% in perovskite solar cells . When
[12]
WO is used as the HTL, the formation of Sb-W bonds at the Sb Se /WO interface creates an interface
2
3
3-x
3-x
dipole, which not only reduces the hole extraction barrier but also effectively suppresses back interface
recombination in Sb Se devices . Additionally, first-principles calculations by Professor Chen's team
[13]
3
2
demonstrated that Zn doping in Sb S can lower the Fermi level and increase the conductivity [14,15] . And Tang
2 3
et al. further confirmed that solution-processed Zn doping can elevate the back surface energy level of Sb S ,
2 3
improve carrier transport, and reduce interface recombination . These strategies based on oxide buffer
[16]
layers or metal element doping all provide effective ways to improve the photovoltaic performance of Sb S .
2 3
Building on interface engineering and doping strategies, this work employs an ultrathin ZnO layer as an
oxygen diffusion barrier, referred to as a “breathing membrane”. This layer enables controlled oxygen