CZTSSe薄膜与Mo背电极接触特性的数值分析

Numerical Analysis of Contact Characteristics between CZTSSe Thin Film and Mo Back Electrode

为分析CZTSSe薄膜太阳能电池的背电极接触特性,采用AFORS-HET(Automat for Simulation of HETerostructures)v2.5软件对CZTSSe/Mo(S,Se)2/Mo结构进行数值分析,研究CZTSSe的带隙和电子亲和能、Mo(S,Se)2界面层的厚度以及带隙对CZTSSe与Mo电极的电学接触特性的影响。结果表明CZTSSe的带隙和电子亲和能的增大,使得CZTSSe/Mo(S,Se)2/Mo的欧姆接触减弱并向整流接触转变;对于带隙较窄的CZTSSe,加入界面层使CZTSSe/Mo(S,Se)2/Mo形成的欧姆接触转变为整流接触,随着界面层厚度的增大,整流接触逐渐减弱;对于带隙较宽的CZTSSe,加入2 nm的界面层使得CZTSSe/Mo(S,Se)2/Mo形成的整流接触增强,但随着界面层厚度的继续增大,整流接触减弱。当CZTSSe的带隙和电子亲和能较小时,CZTSSe/Mo(S,Se)2/Mo形成欧姆接触,控制界面层厚度为100 nm左右可以得到最优的电学接触特性。

In order to analyze the back electrode contact characteristics of CZTSSe thin film solar cells,the CZTSSe/Mo(S,Se)2/Mo structure was simulated by AFORS-HET v2.5 software.The effects of the band gap Eg and the electron affinity of CZTSSe and the thickness and the band gap of Mo(S,Se)2 interface layer on the electrical contact characteristics between CZTSSe and Mo electrodes were investigated.The results show that the increases of the band gap and electron affinity of CZTSSe make the ohmic contact of CZTSSe/Mo(S,Se)2/Mo weaken and transform to the rectifying contact.For CZTSSe with a narrow band gap,the addition of the interface layer causes the ohmic contact formed by CZTSSe/Mo(S,Se)2/Mo to be converted into a rectifying contact.As the thickness of the interface layer increases,the rectifying contact weakens.For CZTSSe with a wide band gap,the addition of a 2 nm interface layer enhances the rectifying contact formed by CZTSSe/Mo(S,Se)2/Mo.As the thickness of the interface layer increases,the rectifying contact weakens.When the work function of CZTSSe is low,CZTSSe/Mo(S,Se)2/Mo forms an ohmic contact,and the optimal electrical contact characteristics can be obtained by controlling the thickness of the interface layer to about 100 nm.