Enhancement of output performance of Cu2ZnSnS4 thin film solar cells—A numerical simulation approach and comparison to experiments

Narrow-bandgap Cu2Sn1−xGexSe3 thin film solar cells

“…Especially, the cell performance was dramatically degraded when the thickness of absorber layer is less than 1 μm. However, the relative increment in conversion efficiency of CIGS and CZTS solar cells was around 13 %, when the thickness of absorber layer was increased from 1.0 to 1.5 μm [22,23]. Thus, a significant improvement in cell performance can be mainly attributed to improved film morphology, reduction of the carrier concentration, and bandgap widening by Ge incorporation, not to the thickness change of absorber layer.…”

“…shown that the cell performance can be improved by increasing the thickness of absorber layer [22,23]. This is mainly because that the thicker absorber layer absorb more photon and reduce recombination at the back contact.…”

Loss mechanisms influence on Cu2ZnSnS4/CdS-based thin film solar cell performance

“…Table 1 shows ZnO:Al, ZnO and CdS material parameters used in the simulation which were selected based on experimental values reported on literature and theory. These parameters have been broadly used for modeling CIGS, CdTe and kesterite solar cells [23,25,26,[28][29][30][31]. On the other hand, most CZTS material properties used in the simulation were taken from the electrical and optical characterization results reported for CZTS-based solar cells with record efficiencies [1,32].…”

“…Furthermore, a conduction band-offset (DE C ) of 0.24 eV was taken into consideration as measured for CdS/CZTS heterojunction [10]. Moreover, a relative dielectric permittivity value of 10 was considered for CZTS compound as reported elsewhere [26,[28][29][30]34]. CZTS electron and hole effective masses were used to calculate the effective density of states of the conduction band (N c ) and the valence band (N v ).…”

“…Conversely, from CZTS minority carrier lifetime and mobility values reported for solar cells with record efficiencies, the minority carrier diffusion coefficient and diffusion length values are found. A front and back surface recombination velocity value of 10 5 cm/s for CdS and CZTS minority carriers was taken into account as reported [26,28]. Relative dielectric permittivity values for CdS and CZTS, CZTS acceptor concentration and CdS donor concentration values are used to calculate depletion zone characteristics (built-in voltage, CdS and CZTS depletion zone widths, and electric field) by means of the Poisson equation [17].…”