First-principles study of Cu2ZnSnS4 and the related band offsets for photovoltaic applications

Interface-Centric Strategies in Kesterite Solar Cells: Addressing Challenges, Solutions, and Future Directions for Efficient Solar-Harvesting Technologies

As reserves of non-renewable energy sources decline, the search for sustainable alternatives becomes increasingly critical. Next-generation energy materials play a key role in this quest by enabling the manipulation of properties for effective energy solutions and understanding interfaces to enhance energy yield. Studying these interfaces is essential for managing charge transport in optoelectronic devices, yet it presents significant challenges. This review emphasizes the critical role of interfaces in kesterite solar cells (KSCs), focusing on interfacial architecture, carrier losses, and non-radiative recombination. This review highlights the importance of addressing interface issues and utilizing advanced characterization tools to reveal interface properties. Current interface problems are addressed, recent advancements in interface engineering are summarized, and perspectives on future challenges and prospects are offered. The goal is to illuminate the nature of interfaces and tackle interface losses, which are crucial for improving device design and performance. Despite their pivotal role in device operation, comprehensive reviews on interfaces are lacking, underscoring the relevance of the work for researchers in material interfaces and device engineering. It is hoped that this article will spark interest and inspire further research into interface studies and the mitigation of interface losses.

A Deep Dive into Cu2ZnSnS4 (CZTS) Solar Cells: A Review of Exploring Roadblocks, Breakthroughs, and Shaping the Future

Renewable energy is crucial for sustainable future, and Cu2ZnSnS4 (CZTS) based solar cells shine as a beacon of hope. CZTS, composed of abundant, low-cost, and non-toxic elements, shares similarities with Cu(In,Ga)Se2 (CIGS). However, despite its promise and appealing properties for solar cells, CZTS-based solar cells faces performance challenges owing to inherent issues with CZTS material, and conventional substrate structure complexities. This review critically examines these roadblocks, explores ongoing efforts and breakthroughs, providing insight into the evolving landscape of CZTS-based solar cells research. Furthermore, as an optimistic turn in the field, the review first highlights the crucial need to transition to a superstrate structure for CZTS-based single junction devices, and summarizes the substantial progress made in this direction. Subsequently, dive into the discussion about the fascinating realm of CZTS-based tandem devices, providing an overview of the existing literature as well as outlining the possible potential strategies for enhancing the efficiency of such devices. Finally, the review provides a useful outlook that outlines the priorities for future research and suggesting where efforts should concentrate to shape the future of CZTS-based solar cells.

Current Status of the Open-Circuit Voltage of Kesterite CZTS Absorber Layers for Photovoltaic Applications-Part I, a Review

Herein, based on the reviewed literature, the current marketability challenges faced by kesterite CZTS based-solar cells is addressed. A knowledge update about the attempts to reduce the open circuit voltage deficit of kesterite CZTS solar cells will be addressed, with a focus on the impact of Cu/Zn order/disorder and of Se doping. This review also presents the strengths and weaknesses of the most commercially attractive synthesis methods for synthesizing thin kesterite CZTS films for photovoltaic applications.

Developing the amazing photocatalyst of ZnAg2GeSe4, ZnAg2Ge0.93Fe0.07Se4 and ZnAg2Ge0.86Fe0.14Se4 through the computational explorations by four DFT functionals

For developing the stannite type quarterly crystal photocatalyst, the electronic structure and optical properties of ZnAg₂GeSe₄, ZnAg₂Ge_0.93Fe_0.07Se₄ and ZnAg₂Ge_0.86Fe_0.14Se₄ were calculated and compared with the parent stannite type quarterly crystal, ZnAg₂GeS₄. First of all, the four functionals, such as GGA with PBE, GGA with RPBE, GGA with WC and LDA with CA-PZ functionals were used for primary screening of electronic band structure and structural geometry for ZnAg₂GeS₄ while the band gap was in 0.93, 0.97, 0.77 and 0.67 eV, respectively. It must be mentioned that the experimental value of ZnAg₂GeS₄ was 0.94 eV so that the GGA with PBE showed the overlapping value of band gap. The main focus of this paper is to evaluate the band structure of newly predicted the stannite type quarterly crystal, ZnAg₂GeSe₄ using four methods replacing the Sulfur atom by Serium atom on ZnAg₂GeS₄. The band gap for four methods, such as GGA with PBE, GGA with RPBE, GGA with WC and LDA with CA-PZ functionals, were calculated in 0.84 eV, 0.92 eV, 0.68 eV and 0.58 eV. Afterward, Fe atom was doped by two portions, like 7% and 14%, to make the empirical formula, ZnAg₂Ge_0.93Fe_0.07Se₄ and ZnAg₂Ge_0.86Fe_0.14Se₄. The numerical values of band gaps for ZnAg₂Ge_0.93Fe_0.07Se₄ and ZnAg₂Ge_0.86Fe_0.14Se₄ were 0.43 eV, 0.53 eV, 0.35 eV and 0.18 eV and 0.24 eV, 0.31 eV, 0.18 eV and 0.08 eV, respectively, using the four respected DFT methods. For their contributed orbitals of each atom on crystal, the density of state and the partial density of state for ZnAg₂GeSe₄, ZnAg₂Ge_0.93Fe_0.07Se₄ and ZnAg₂Ge_0.86Fe_0.14Se₄ crystals were simulated through the GGA with PBE method as standard regarding the calculation of band gap study comparison with experimental magnitude. For giving the further information about the nature in case of optical evidence, the six optical properties, such as absorption, reflection, refractive index, conductivity, dielectric function and loss function were calculated, and make a comparative study. In case of UV light absorption in lighten to optical parameters, the ZnAg₂Ge_0.86Fe_0.14Se₄ can show the highest absorption up to convenience energy region as photocatalyst.

Density Functional Theory and Experimental Determination of Band Gaps and Lattice Parameters in Kesterite Cu2ZnSn(SxSe1-x)4

The structures and band gaps of copper-zinc-tin selenosulfides (CZTSSe) are investigated for a range of anion compositions through experimental analysis and complementary first-principles simulations. The band gap was found to be extremely sensitive to the Sn-anion bond length, with an almost linear correlation with the average Sn-anion bond length in the mixed anion phase Cu₂ZnSn(S_xSe_1-x)₄. Therefore, an accurate prediction of band gaps using first-principles methods requires the accurate reproduction of the experimental bond lengths. This is challenging for many widely used approaches that are suitable for large supercells. The HSE06 functional was found to predict the structure and band gap in good agreement with the experiment but is computationally expensive for large supercells. It was shown that a geometry optimization with the MS2 meta-GGA functional followed by a single point calculation of electronic properties using HSE06 is a reasonable compromise for modeling larger supercells that are often unavoidable in the study of point and extended defects.

Improving Carrier-Transport Properties of CZTS by Mg Incorporation with Spray Pyrolysis

High nonradiative recombination, low diffusion length and band tailing are often associated with a large open circuit voltage deficit, which results in low efficiency of Cu₂ZnSnS₄ (CZTS) solar cells. Recently, cation substitution in CZTS has gained interest as a plausible solution to suppress these issues. However, the common substitutes, Ag and Cd, are not ideal due to their scarcity and toxicity. Other transition-metal candidates (e.g., Mn, Fe, Co, or Ni) are multivalent, which may form harmful deep-level defects. Magnesium, as one of the viable substitutes, does not have these issues, as it is very stable in +2 oxidation state, abundant, and nontoxic. In this study, we investigate the effect of Mg incorporation in sulfur-based Cu₂ZnSnS₄ to form Cu₂Mg_xZn_1-xSnS₄ by varying x from 0.0 to 1.0. These films were fabricated by chemical spray pyrolysis and the subsequent sulfurization process. At a high Mg content, it is found that Mg does not replace Zn to form a quaternary compound, which leads to the appearance of the secondary phases in the sample. However, a low Mg content (Cu₂Mg_0.05Zn_0.95SnS₄) improves the power conversion efficiency from 5.10% (CZTS) to 6.73%. The improvement is correlated to the better carrier-transport properties, as shown by a lesser amount of the ZnS secondary phase, higher carrier mobility, and shallower acceptor defects level. In addition, the Cu₂Mg_0.05Zn_0.95SnS₄ device also shows better charge-collection property based on the higher fill factor and quantum efficiency despite having lower depletion width. Therefore, we believe that the addition of a small amount of Mg is another viable route to improve the performance of the CZTS solar cell.