Temperature dependence of VOC in CdTe and Cu(InGa)(SeS)2-based solar cells

Abstract

The temperature and intensity dependence of Voe in CdTe and Cu(lnGa)(SeS)2 polycrystalline thin film solar cells was examined.Voe was measured from 100-330K and from 0.1 to 1 sun illumination. Two distinct regimes of temperature dependence are commonly observed: a linear regime at higher temperatures with slope -0.5 to -3 mV/K and a logarithmic intensity dependence; and a saturation regime at lower temperatures, with little intensity or temperature dependence. The T=O K intercept extrapolated from the linear regime around 300K is related to the activation energy of the dominant recombination mechanism and is equal to the absorber bandgap for Shockley-Read-Hall recombination, or in some cases, from heterojunction interface recombination, which is less than the absorber bandgap. In this work, the temperature dependence of Voe will be characterized for CdTe and Cu(lnGa)Se2 devices with differences in composition and processingconditions. Analysis will focus on the activation energy of the recombination mechanism and saturation at lower temperatures which indicates a maximum separation of the quasi Fermi levels as thermally activated SRH recombination is frozen out. The saturation voltage is -1 V for a typical CdTe device (E g=1.45 eV), -1V for low bandgap Cu(lnGa)Se2 (Eg=1.15), and -1.

Development of a Low Cost Insulated Foil Substrate for Cu(InGaSe)2 Photovoltaics

“…Development samples were found to have significantly lower V oc than that of the SLG sample, which has been typically observed in a previous study (10) . Since Process 2 has shown better device performance with the flexible SS/SBR substrates, it has been employed as the baseline process for the rest of the present work.…”

“…Firstly, higher Na incorporation significantly promoted V oc and consequently the conversion efficiency. Previous analysis of Na free Cu(InGa)Se 2 devices do not operate through the recombination in the absorber space charge region via SRH mechanism and may be controlled through interface recombination resulting in lower V oc (10) . The same explanation could be applied to the Cu(InGa)(SeS) 2 devices with various NaF thicknesses.…”

Variation of Quantum Efficiency in CZTSSe Solar Cells with Temperature and Bias Dependence by SCAPS Simulation

“…3. As expected, the reduction in temperature reduces the net dominant recombination mechanism which also improves Voc [18]. Consequently, the spectral responses in Q-E increases as temperature decreases from 300 K to 200 K. The regions from 500 nm to 900 nm show the Q-E reduction compared to a slight change in the other regions.…”

Analysis and comparison of different selenization routes for nanoparticle ink deposited Cu(In<inf>1−x</inf>Ga<inf>x</inf>)(Se<inf>y</inf>S<inf>1−y</inf>)<inf>2</inf> solar cells

“…The low temperature saturation of the V oc gives the maximum Fermi level splitting in the device [9]. The V oc of the H 2 Se device starts to saturate at temperatures below 140K to a value <0.9V.…”