Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu2ZnSn(S,Se)4 solar cells

Abstract

Electrostatic Spray-Assisted Vapor Deposition (ESAVD) is a non-vacuum and cost-effective method to deposit metal oxide, various sulphide and chalcogenide at large scale. In this work, ESAVD was used to deposit Cu2ZnSn(S1−xSex)4 (CZTSSe) absorber. Different alkali metals like Na, Li and Rb were incorporated in CZTSSe compounds to further improve the photovoltaic performances of related devices. In addition, to the best of our knowledge, no experimental study has been carried out to test the effect of Li and Rb incorporation in CZTSSe solar cells. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and glow discharge spectroscopy have been used to characterize the phase purity, morphology and composition of as-deposited CZTSSe thin films. Photovoltaic properties of the resulting devices were determined by completing the solar cells as follows: Mo/CZTSSe/CdS/i-ZnO/Al:ZnO/Ni/Al. The results showed that Li, Na and Rb incorporation can increase power conversion efficiency of CZTS devices up to 5.5%. The introduction of a thiourea treatment, has improved the quality of the absorber|buffer interface, pushed the device efficiency up to 6.3% which is at the moment the best reported result for ESAVD deposited CZTSSe solar cells.

Complex Interplay between Absorber Composition and Alkali Doping in High‐Efficiency Kesterite Solar Cells

“…Strikingly, the dependency of the Sn content on the highest device performance of different alkali elements [10] Na > Cs > K > Rb > Li "Efficiency enhancement of Cu 2 ZnSn(S,Se) 4 solar cells via alkali metals doping" [11] K > Rb > Na > Li > Cs "Influence of alkali metals (Na, Li, Rb) on the performance of electrostatic spray-assisted vapor deposited Cu 2 ZnSn(S,Se) 4 solar cells" [12] Li > Na > Rb "Alkali doping strategies for flexible and lightweight Cu 2 ZnSnSe 4 solar cells" [13] K > Na has neither been reported before nor taken into account in earlier publications that compared the effects of alkali elements on kesterite solar cells. [10][11][12][13] The influence of Sn content on V OC , J SC , and FF is shown in Figure 3a-c for the "high" alkali content samples. As a result of the qualitatively distinct behavior of Li, Na, and K (light alkali elements) on the one hand and Rb and Cs (heavy alkali elements) on the other, it is helpful to separate them into two groups.…”

“…[8,9] Several studies comparing different alkali elements and their effect on solar cell properties and device performance have recently been published. [10][11][12][13] Table 1 compares the effects on device performance by extracting a ranking of the various alkali elements in each publication in the order of their capability to improve device performance. It is apparent from these rankings that no consistent experimental results have been obtained, which triggers two questions: (i) Why do the published results differ so much?…”

Electrodeposition Conditions Effect Sb2Se3 Thin‐Film Properties

“…In turn, replacing the anion SO 4 À , in (NH 4 ) 2 SO 4 S.E., for Cl À inhibits Sb incorporation and the film becomes Se-rich (F-film, Table 2). [41] These facts make us conclude that the nature of the S.E. [41] These facts make us conclude that the nature of the S.E.…”

Optimization of Cu2ZnSnS4 Absorber Layers via Sulfurization of Electrodeposited Cu-Zn-Sn Precursors for Photovoltaic Applications

“…Enhance grain growth and (112) orientation Increase in solar cell efficiency [154,158,160] Bismuth has been shown to work as a fluxing element, although it has been studied only to a limited extent for CZTS or CIGS materials [162][163][164]. These studies are in agreement on the occurrence of a growth modifier role of Bi with regard to CZTS and CIGS crystal growth;…”

“…It is well understood that the crystallographic properties of polycrystalline absorber layers, such as CZTS and CIGS, are important for the solar cell efficiency [154][155][156][157]. One way to improve the crystallinity of semiconductor layers is to use a suitable element to enhance the grain growth of the CZTS layers [155,156,158].…”