Research Of Cu₂ZnSnSe₄Thin Film Solar Cell

Cu₂ZnSnSe₄semiconductor materials as a new type absorption layer of thinfilm solar cell, because its direct band gap is1.0eV and optical absorptioncoefficient is more than104cm-1and has excellent photoelectric effect of p-typematerials to be widely researched. Cu₂ZnSnSe₄thin film solar cell has developedrapidly in recent years, has now reached10.1%of the photoelectric conversionefficiency. To reduce the costs of fabricate copper zinc tin selenium thin-film solarcells, it is need to develop a kind of non-vacuum method to preparation thin film.Electrochemical deposition method and sol-gel method, chemical bath are based onthe solution method, they have lots of advantage as: low cost, environment friendly,operation simple, the composition is easy to control, large area deposition so theyhave a great application prospect. However one-step electrochemical and sol-gel todeposition a few of elements on the substrate at the same times is still exist manyproblems, so the ratio of the elements and the pH in the electrolyte solution must beadjusted to make the precursors conform to the stoichiometric ratio of Cu₂ZnSnSe₄.Thin film solar cells structure contain back contact layer, absorbing layer, bufferlayer, the window layer and the Ni/Al electrodes. This paper taken Cu₂ZnSnSe₄asabsorbing layer form the thin film solar cells, the main research work of this paperis as follows:（1） Fabricated back contact layer （Mo） by using DC magnetron sputtering.Under the pressure of9.0×10^-4Pa, filled with argon to1.1Pa, sputtering power is30W for9min, then adjust the pressure to0.5Pa, under the sputter power of90Wfor8min. The prepared Duplex Mo layer, its structure, adhesion conductivity areexcellent.（2） Researched the method of Cu₂ZnSnSe₄thin films prepared by selenizitedone-step co-electroplated Cu-Zn-Sn-Se precursors. Seven kinds of differentconcentration and pH value of the electrolyte were prepared to deposit Cu₂ZnSnSe₄,it is found that when the electrolytic solution of Cu: Zn: Sn: Se=3:70:20:3and thepH is1.6, the pure stoichiometric kesterite type Cu₂ZnSnSe₄was fabricated at thetemperature550degrees selenium atmosphere. The impurity phases in the samples which prepared from different electrolyte were studied to determine the growthmechanism of Cu₂ZnSnSe₄film.（3） The technology of fabricate Cu-Zn-Sn precursors by sol-gel was studied,the mix of electrolyte was optimized.17mL ethylene glycol monomethyl ether and3mL MEA were used as the solvent and the stabilizer,18mmol copper （Ⅱ） acetatemonohydrate,8mmol zinc acetate dehydrate and10mmol tin （Ⅱ） chloridehidydrate were added in. The precursors were annealed by a temperature programwhere the temperature was increased to550degrees. Deposited Cu₂ZnSnSe₄ondifferent substrates to study whether there is MoSe2on the interface of Mo andCu₂ZnSnSe₄after selenization.（4） The crystallization mechanism of CdS thin films prepared by chemicalbath was studied. It is found that using acetic acid system to deposit CdS thin filmthat made film surface more compact. Research of radio frequency （RF） magnetronsputtering to prepare i-ZnO thin films, dc magnetron sputtering to prepare AZOthin films and evaporation to prepare Ni/Al electrode. Assembled theSLG/Mo/CZTSe/CdS/i-ZnO/AZO/Ni/Al thin film solar cells which the absorb layerwas made by sol-gel method, the efficiency of this solar cell is0.296%.