Zn1 xMgxO as a window layer in completely Cd free Cu In,Ga S,Se 2 based thin film solar cells

In order to yield high efficiency CdS free chalcopyrite based solar cells, the conventional i ZnO layer is replaced by a Zn1 xMgxO alloy. Solar cells without a CdS buffer layer processed in a entirely ?dry? inline process with a Mg content of x 0.30 yielded efficiencies of up to 12.5 . The intention of this article is to clarify the beneficial effect of this substitution by means of analyzing the properties of the new alloy and the solar cell characteristics in dependence of three Mg contents x 0, 0.15, 0.30

Direct determination of the band alignment at the Zn,Mg O CISSe interface

The electronic and chemical properties of the Zn1 x,Mgx O CuIn S,Se 2 interface, prepared by sputtering of thin Zn,Mg O layers, were investigated with direct and inverse photoelectron spectroscopy on in situ prepared samples. With the combination of both techniques we have determined the band alignment at this interface as a function of Mg content in the range 0 lt; x lt; 0.30. We find that the band alignment at the interface can be tailored between a cliff downward step in the conduction band for pure ZnO and a spike upward step for high Mg contents. A direct influence of the band alignment modifications on the solar cell parameters is found

High performance thin film Cu chalcopyrite pv devices with a Zn S,O buffer layer

The use of Zn S,O as a buffer layer for Cd free Cu chalcopyrite based thin film photovoltaic devices has recently been successfully up scaled from laboratory scale 0.5 cm2 single cell devices to large area solar modules up to 900 cm2 . The buffer layers are deposited using a chemical bath deposition CBD process developed at the Helmholtz Zentrum Berlin für Materialien und Energie HZB , which introduces a new type of complexation that avoids the formation of agglomerates during the deposition process. This results in homogeneous and compact nanocrystalline buffer layers as revealed by scanning and transmission electron microscopy. The CBD process is monitored to obtain reproducible results by measuring the transparency of the solution during buffer deposition. The absorbers used in this study are Cu In,Ga S,Se 2 CIGSSe delivered by AVANCIS GmbH amp; Co. KG AVANCIS and CuInS2 CIS delivered by Sulfurcell Solartechnik GmbH SCG . Previous published results presented solar cell devices 0.5 cm2 with efficiencies of 14.2 CIGSSe and 8.5 CIS and solar modules 30x30 cm3 with efficiencies of 12.5 CIGSSe and 6.6 CIS and a deposition time of approximately 20 minutes. Now further efforts have been focused on reducing the total processing time by varying the conditions of the chemical bath, enhancing the deposition rate and increasing the potential yield as a necessary step to fulfill before transferring the process to a pilot line. Efficiencies of 12 on 30x30 cm2 CIGSSe and 7.1 on 10x10 cm2 CIS absorbers with deposition times below 10 minutes are presented in this pape

Use of different Zn precursors for the deposition of Zn S,O buffer layers by chemical bath for chalcopyrite based Cd free thin film solar cells

Progress in fabricating Cu In,Ga S,Se 2 CIGSSe solar cells with Zn S,O buffer layers prepared by chemical bath deposition CBD is discussed. The effect of different Zn salt precursors on solar cell device performance is investigated using production scale CIGSSe absorbers provided by AVANCIS GmbH amp; Co. KG. The CBD process has been developed at the Hahn Meitner Institut HMI using zinc nitrate, zinc sulphate or zinc chloride as zinc precursor. An average efficiency of 14.2 0.8 is obtained by using one layer CBD Zn S,O . The dominant recombination path for well performing solar cells is discussed based on the results obtained from temperature dependent J V analysis. The structure and morphology of buffer layers deposited using zinc nitrate and zinc sulphate has been studied by means of transmission electron micrographs of glass Mo CIGSSe Zn S,O structures. Results show a conformal coverage of the absorber by a Zn S,O layer of 15 25 nm consisting of nanocrystals with radii of 5 nm. XAES analysis of the buffer layer reveals a similar surface composition for buffer layers deposited with zinc nitrate and zinc sulphat