Comparison of device performance and measured transport parameters in widely-varying Cu(In,Ga) (Se,S) solar cells

Abstract

We report the results of an extensive study employing numerous methods to characterize carrier transport within copper indium gallium sulfoselenide (CIGSS) photovoltaic devices, whose absorber layers were fabricated by diverse process methods in multiple laboratories. This collection of samples exhibits a wide variation of morphologies, compositions, and solar power conversion efficiencies. An extensive characterization of transport properties is reported here -including those derived from capacitance-voltage, admittance spectroscopy, deep level transient spectroscopy, time-resolved photoluminescence, Auger emission profiling, Hall effect, and drive level capacitance profiling. Data from each technique were examined for correlation with device performance, and those providing indicators of related properties were compared to determine which techniques and interpretations provide credible values for transport properties. Although these transport properties are not sufficient to predict all aspects of current-voltage characteristics, we have identified specific physical and transport characterization methods that can be combined using a model-based analysis algorithm to provide a quantitative prediction of voltage loss within the absorber. The approach has potential as a tool to optimize and understand device performance irrespective of the specific

Non-toxic complexing agent Tri-sodium citrate’s effect on chemical bath deposited ZnS thin films and its growth mechanism

“…Although ZnS thin films are deposited successfully using the above mentioned non-toxic complexing agents, the deposited thin films indicated poor crystallinity, rough morphology, and discontinuous microstructures. These characteristics indicate low efficiency in the TFSCs [33]. Citrate anions ððC 6 H 5 O 7 Þ 3À Þ in solution can be obtained from one to three carboxylate groups, depending on the pH of the reaction solution [34].…”

Charge-neutral disorder and polytypes in heterovalent wurtzite-based ternary semiconductors: The importance of the octet rule

“…The II-IV-V 2 and I-III-VI 2 compounds based on the zincblende lattice are well known to order in the chalcopyrite structure 1,2 and have received significant attention for their nonlinear optical properties and photovoltaic applications. For example, Cu(In,Ga)(S,Se) 2 thin films are widely used in photovoltaics [3][4][5] and ZnGeP 2 , CdGeAs 2 and AgGa(Se,Te) 2 single crystals are used as frequency doublers and parametric oscillators in nonlinear optical applications. [6][7][8] Order-disorder transitions of these chalcopyrite materials have been reported, with the disordered state apparently exhibiting the binary, parent zincblende structure in x-ray diffraction spectra.…”

Comparison of amorphous InZnO and polycrystalline ZnO:Al conductive layers for CIGS solar cells

“…In general, however, the currents integrated from QE's reinforce the same trend as that from I-V measurements and the TCO's properties. c-vmeasurements than 15% ty~ically' have a carrier concentration in the 1 x 10 15 -2 x 10 6 cm-3 range and a depletion width in the 0.2-0.8 IJm range [8][9][10][11]. Figure 3 shows that the carrier concentrations and the depletion widths for the various devices with IZO as the conducting layer are all within the typical ranges.…”