Role of ZnS Particles in the Performance of Cu₂ZnSnS₄ Thin Film Solar Cells: A Comparative Study by Active Control of Zinc Deposition in Coevaporated Precursors

Abstract

Formation of ZnS particles in the Cu2ZnSnS4 (CZTS) light absorber layer of CZTS solar cells may impede the photocarrier collection as well as the open circuit voltage. Coevaporation of Cu, Zn, Sn, and S elements can provide a uniform and well‐mixed Cu–Zn–Sn–S precursor at atomic level, yet the annealing/sulfurization process does not preserve such elemental distribution. The Zn element in the formed CZTS absorber thin films from such a uniform precursor distributes unevenly, especially aggregating near the rear interface, and thus deteriorates the film quality. Herein, the movement pathway of the Zn element in the coevaporated precursor during annealing is investigated through energy dispersive X‐ray spectroscopy (EDX) mapping and secondary ion mass spectroscopy (SIMS) profiling. With the understanding of the segregation behavior of the Zn element, an active manipulation of the initial distribution of Zn in the precursor is accordingly designed to effectively alleviate the accumulation of Zn near the rear Mo/CZTS interface and therefore improve the crystalline quality of the absorber. The results suggest that properly controlling the precursor.

Rear Interface Modification by the ZnTe Layer Enables High-Efficient Cu2(Zn,Cd)SnS4Thin-Film Solar Cells

“…The complete XRD patterns can be viewed in Figure S3. From them, it is noted that most peaks could be assigned to the CZTS phase, representing a kesterite structure with (112) preferred orientation (JCPDS card no.26-0575), consistent with previous results. ,, In addition to the CZTS phase, two peaks, one at 2θ ≈ 11.5 o assigned to the S x phase (PDF, #08-0247) and another at 2θ ≈ 31.9 o that belonged to the SnS x phase (PDF, #53-0526), are observed for the absorber in the reference solar cell. The formation of secondary phases could be explained by the following reaction …”

“…From them, it is noted that most peaks could be assigned to the CZTS phase, representing a kesterite structure with (112) preferred orientation (JCPDS card no.26-0575), consistent with previous results. 18,27,28 In addition to the CZTS phase, two peaks, one at 2θ ≈ 11.5 o assigned to the S x phase (PDF, #08-0247) and another at 2θ ≈ 31.9 o that The ideality factor A and saturation current density J 0 are determined from dark J−V curves. J* refers to the leakage current density at −1 V bias.…”

A critical review on rational composition engineering in kesterite photovoltaic devices: self-regulation and mutual synergy

“…25,42 Under this condition, the role of the inevitable Zn(S,Se) secondary phase in the CZTSSe solar cell performance is closely dependent on its location. [43][44][45][46] Furthermore, the classic bandgap gradient structure across the CIGSSe lms through adjusting the [Ga]/([Ga] + [In]) ratio cannot be implemented in CZTSSe absorbers by tailoring cation composition. 47,48 This further aggravates the difference in the device performance, although the strategies of external cation substitution and alloying have been broadly employed to regulate the bandgap, 14,[49][50][51][52][53] and there is still much work le to be done.…”

Direct, simple, rapid, and real‐time monitoring of ultraviolet B level in sunlight using a self‐powered and flexible photodetector

“…Zinc sulfide (ZnS) is a well‐known metal chalcogenide with a tunable bandgap (3.4–4.68 eV) depending on its particle size 4–7 . Accordingly, ZnS has been used as a key component in various state‐of‐the‐art optoelectronics, such as solar cells, light‐emitting diodes, and UV photodetectors 5,8,9 . Regarding research on UV photodetector, X. Fang et al first introduced single‐crystalline ZnS nanobelts as an efficient photo‐absorber for visible‐blind UVB detection 10,11 .…”

“…[4][5][6][7] Accordingly, ZnS has been used as a key component in various state-of-the-art optoelectronics, such as solar cells, light-emitting diodes, and UV photodetectors. 5,8,9 Regarding research on UV photodetector, X. Fang et al first introduced single-crystalline ZnS nanobelts as an efficient photo-absorber for visibleblind UVB detection. 10,11 The ideal bandgap of ZnS for UVB-C detection should be 3.87 eV, estimated from the relation E = hc/λ, where h is the Planck constant (4.14 Â 10 À15 eV s), c is the velocity of light (2.98 Â 10 8 m s À1 ), and λ = 320 nm (maximum wavelength of UVB).…”