Highly efficient Cu2ZnSn(S,Se)4 bifacial solar cell via a composition gradient strategy through the molecular ink

Abstract

The use of transparent conducting oxide (TCO) as a substrate in Cu 2 ZnSn(S,Se) 4 (CZTSSe) thin-film solar cells allows for advanced applications, such as bifacial, semitransparent, and tandem solar cells with the capability to increase power density generation. However, the efficiency of this kind of solar cell is still below 6% based on the low-cost solution process. In this work, we develop a composition gradient strategy and demonstrate a 6.82% efficient CZTSSe solar cell on F:SnO 2 (FTO) substrate under the ambient condition. The composition gradient is realized by simply depositing the precursor inks with different Zn/Sn ratios. To verify that the high performance of the solar cell is attributed to the composition gradient strategy rather than the sole change of the Zn/Sn ratio, devices based on absorbers with varied Zn/Sn ratios are fabricated. Furthermore, the structure and surface morphology of the CZTSSe films with/without composition gradients are examined. The presence of elemental gradient through the depth of the CZTSSe films before and after annealing is confirmed by secondary ion mass spectroscopy analysis. It is found that the composition gradient enhances the crystallinity of the absorber, reduces the surface roughness as well as device parasitic losses, contributing to a higher fill factor, open-circuit voltage , and conversion efficiency.

Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co–Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc–air batteries

“…32 Existing research suggested that changing the morphologies can change catalytic performance. 33 It is therefore still highly desirable but challenging to develop novel methods for the synthesis of morphology-controlled MOF templates to get customized active components and structures with high electrocatalytic performance. 34,35 In practice, controlling coordination geometry like oxidation state of metal cations, binding modes of ligands and solvent molecules is critical for the creation of MOFs with morphological and structural diversity.…”

11.4% Efficiency Kesterite Solar Cells on Transparent Electrode

“…The 7.02% PCE reported here is already higher than state‐of‐the‐art CZTSSe solar cells on bare transparent substrates, which exhibited an efficiency of 6.82%. [ 13 ] The higher performance reveals better absorber quality, which is benefited from the unique direct phase transformation reaction path of the absorber fabricated from Sn 4+ ‐based DMSO solution. [ 20 ] The reaction path and grain growth will be further discussed later.…”

“…[ 9 ] in 2012 with the CZTS absorber fabricated on fluorine‐doped tin oxide (FTO)‐coated glass by successive ionic layer adsorption and reaction. Later, a few groups have reported kesterite solar cells on FTO [ 10–17 ] or indium tin oxides (ITO) [ 14–15 ] with the absorbers deposited either by vacuum [ 11–12,14–16 ] or solution methods. [ 13,17 ] For example, Wang et al.…”

“…Later, a few groups have reported kesterite solar cells on FTO [ 10–17 ] or indium tin oxides (ITO) [ 14–15 ] with the absorbers deposited either by vacuum [ 11–12,14–16 ] or solution methods. [ 13,17 ] For example, Wang et al. [ 10 ] reported 4.73% CZTS solar cell via coelectrodeposition process.…”

“…For solution‐based devices, the highest efficiency is 6.82% reported by Khan et al. [ 13 ] The so far reported kesterite solar cells on transparent substrates are summarized in Table S1, Supporting Information.…”