CZTSSe

While the standard interpretation treats CdS/CdTe, CdS/Cu(In,Ga)Se2(CIGSe) and CdS/kesterites as p-n junctions, some recent reports suggest these solar cells operate rather as a Metal-Insulator-Semiconductor (MIS) structure. In this paper, we report results about the dependence of electrical, optical, morphological and structural properties of CBD-CdS on growth conditions in order to obtain the best layers to be used in solar cells according to the MIS model. In particular, CBD-CdS thin films were synthesized by changing the complexing agents in the bath solution, the Cd source and the nominal S/Cd ratio. In order to study the impact of the different CdS deposition approaches, CIGSe and CZTSe solar cells were processed. The influence of CdS:Cu as well as Cd sources such as Cd(NO3)2 and CdSO4 on solar cell electrical parameters is studied.

We investigated bulk and thin-film samples of the quaternary p-type semiconductor Cu2ZnSnS4 (CZTS) by μSR, in order to characterize the existing muonium signals. We find that the majority of the implanted muons form a diamagnetic state broadened by an interaction with the Cu nuclear moments, which we interpret as Mu+ bound to sulphur. A paramagnetic fraction is also present at low temperatures and the ratio between the two muon charge states, Mu+ and Mu0, varies between 20 and 40% prior to the onset of muon diffusion, which occurs at around 150 K. The fraction of Mu0 is found to be sensitive to the defect content of the sample. The paramagnetic fraction has two different contributions and their origin is discussed and related with the muon role as a probe for charge carriers in the material.

In this work, we have studied the geometric structure and electronic and optical properties of Cu2ZnSn(S1-xSex)4 nanocrystals where x = 0, 0.25, 0.50, 0.75, 1.00 by the quantum-chemical calculations within the framework of DFT. For the electronic and optical properties calculations, the effective XC functional and the TB-mBJ potential were used. The calculated structural characteristics show that the volume of these systems increases with increasing the Se concentration. The electronic properties of the Se-doped kesterite Cu2ZnSnS4 show that the bandgap tends to decrease. It was found that the Se-doped material has noticeably increased its absorption capacity. Hence, the efficiency of the Cu2ZnSnS4 in the IR region of radiation improves. The effective reduction bandgap from 1.455 eV to 0.94 eV is observed, which is in gоod agreement with known experimental data for the pure and undoped systems Cu2ZnSnS4 and Cu2ZnSnSе4. The calculated band gap is 1.346 eV for the Cu2ZnSnS3Se system, which is comparable with the optimal bandgap of semiconductors used in photovoltaic applications. It was found that with the increase of the Se concentration, the absorption coefficient increases, thereby resulting in the materials' reflectivity decrease. The calculated optoelectronic parameters and the density of electronic states indicate that the Cu2ZnSnS4:Se system possesses a favorable property, suitable for applications in solar cells technology.

One of the major challenges in increasing the efficiency of the CZTSSe solar cells is to control the lattice defects formation and secondary phases in the absorber layer of the cells. Moreover, by controlling and decreasing lattice defects and thus improving the efficiency, larger-scale applications would be financially acceptable. In this paper , several CZTSSe thin-film solar cells have been prepared and one device with champion efficiency of 10.33% has been chosen for the modeling. Afterward, numerical simulations based on the Finite Element Method (FEM) and Finite Difference (FD) were conducted on these cells. The effect of defects density and defect types, which are located at different energy levels in the absorber layer bandgap, was evaluated. The results indicated that by decreasing the defects which are located close to the electron Fermi level and the middle of the band gap (), the maximum efficiency of 18.47% for these solar cells can be achieved.

The structure of the electronic energy levels of a single phase Cu2ZnSnS4 film, as confirmed by Raman Scattering and x-ray diffraction, is investigated through a dependence on the excitation power of the photoluminescence (PL). The behavior of the observed asymmetric band, with a peak energy at ∼1.22 eV, is compared with two theoretical models: (i) fluctuating potentials and (ii) donor-acceptor pair transitions. It is shown that the radiative recombination channels in the Cu-poor film are strongly influenced by tail states in the bandgap as a consequence of a heavy doping and compensation levels. The contribution of the PL for the evaluation of secondary phases is also highlighted.

Abstract One of the major challenges in increasing the efficiency of the CZTSSe solar cells is to control the lattice defects formation and secondary phases in the absorber layer of the cells. Moreover, by controlling and decreasing lattice defects and thus improving the efficiency, larger-scale applications would be financially acceptable. In this paper, several CZTSSe thin-film solar cells have been prepared and one device with champion efficiency of 10.33% has been chosen for the modeling. Afterward, numerical simulations based on the Finite Element Method (FEM) and Finite Difference (FD) were conducted on these cells. The effect of defects density and defect types, which are located at different energy levels in the absorber layer bandgap, was evaluated. The results indicated that by decreasing the defects which are located close to the electron Fermi level and the middle of the band gap ( E g / 2 ), the maximum efficiency of 18.47% for these solar cells can be achieved.

One of the major challenges in increasing the efficiency of the CZTSSe solar cells is to control the lattice defects formation and secondary phases in the absorber layer of the cells. Moreover, by controlling and decreasing lattice defects and thus improving the efficiency, larger-scale applications would be financially acceptable. In this paper, several CZTSSe thin-film solar cells have been prepared and one device with champion efficiency of 10.33% has been chosen for the modeling. Afterward, numerical simulations based on the Finite Element Method (FEM) and Finite Difference (FD) were conducted on these cells. The effect of defects density and defect types, which are located at different energy levels in the absorber layer bandgap, was evaluated. The results indicated that by decreasing the defects which are located close to the electron Fermi level and the middle of the band gap (E g /2), the maximum efficiency of 18.47% for these solar cells can be achieved.

We investigated bulk and thin-film samples of the quaternary p-type semiconductor Cu2ZnSnS4 (CZTS) by μSR, in order to characterize the existing muonium signals. We find that the majority of the implanted muons form a diamagnetic state broadened by an interaction with the Cu nuclear moments, which we interpret as Mu+ bound to sulphur. A paramagnetic fraction is also present at low temperatures and the ratio between the two muon charge states, Mu+ and Mu0, varies between 20 and 40% prior to the onset of muon diffusion, which occurs at around 150 K. The fraction of Mu0 is found to be sensitive to the defect content of the sample. The paramagnetic fraction has two different contributions and their origin is discussed and related with the muon role as a probe for charge carriers in the material.