We fabricated polycrystalline Cu2ZnGe x Sn1–x Q4 (Q = S or Se) thin films by using spray-based deposition. The effects of Ge alloying were studied by X-ray diffraction (XRD), Raman spectroscopy, and UV–visible spectroscopy. XRD and Raman spectroscopy revealed that lattice parameters decreased linearly and characteristic Raman peaks shifted to higher frequency with increasing Ge alloying. The band gap energies of postsulfurized CZGTS films (1.51 ± 0.05 to 1.91 ± 0.05 eV) and postselenized CZGTSe films (1.07 ± 0.05 to 1.44 ± 0.05 eV) increased almost linearly with an increase of Ge alloying in the respective films. Analysis of band gap bowing model showed a small bowing constant b ∼ 0.1 ± 0.02 eV, indicating high miscibility of alloyed elements. The band gap tuning of CZGTS­(Se) thin films can be utilized for tuning band gap of subcell in multijunction cell and for band gap graded photoabsorber of high efficient solar cell.

CZFTS) thin films have been fabricated using chemical spray pyrolysis accompanied by postsulfurization. The postsulfurized CZFTS films demonstrate promising morphological, structural, and optical properties for photoabsorber in thin film photovoltaics. The structural transition from stannite to kesterite is found with the increase of zinc content in CZFTS alloy by using X-ray diffraction and Raman spectroscopy. The band gap energies of postsulfurized CZFTS films are observed to be tuned from ∼1.36 ± 0.02 to 1.51 ± 0.02 eV in parabolicincrease trend with increasing Zn content (0 ≤ z ≤ 1). A small bowing constant b ∼ 0.1 ± 0.05 eV deduced from band gap bowing model implicates good miscibility of alloyed constituents in the host crystal lattice.

We analyzed and compared quantitatively the optoelectronic characteristics of perovskite PV devices with and without annealing the perovskite layer in a methyl ammonium chloride vapor atmosphere (MACl treatment).

The performance of perovskite device was found to be influenced by the interface quality and bulk defect activities induced in perovskite grown on HTL during device fabrication.