Simulation of an efficient silicon heterostructure solar cell concept featuring molybdenum oxide carrier‐selective contact

• Published in: International journal of energy research Vol. 42; no. 4; pp. 1563 - 1579
• Main Authors: Mehmood, Haris, Nasser, Hisham, Tauqeer, Tauseef, Hussain, Shahzad, Ozkol, Engin, Turan, Raşit
• Format: Journal Article
• Language: English
• Published: Bognor Regis John Wiley & Sons, Inc 25.03.2018
• Subjects: Absorption; carrier‐selective contact; Computer simulation; Current carriers; Electric contacts; Electrical properties; heterostructure; Industrial production; Mathematical models; Metals; Molybdenum; molybdenum oxide; Molybdenum oxides; Optical properties; Oxides; Photovoltaic cells; Recombination; Schottky barrier; semiconductor; Silicon; Silicon wafers; simulation; Simulators; solar cell; Solar cells; Technology; Thickness; Transition metal oxides
• ISSN: 0363-907X; 1099-114X
• DOI: 10.1002/er.3947

Summary Transition metal oxides/silicon heterocontact solar cells are the subject of intense research efforts owing to their simpler processing steps and reduced parasitic absorption as compared with the traditional silicon heterostructure counterparts. Recently, molybdenum oxide (MoOx, x < 3) has emerged as an integral transition metal oxide for crystalline silicon (cSi)‐based solar cell based on carrier‐selective contacts (CSCs). In this paper, we physically modelled the CSC‐based cSi solar cell featuring MoOx/intrinsic a‐Si:H/n‐type cSi/intrinsic a‐Si:H/n+‐type a‐Si:H for the first time using Silvaco technology computer‐aided design simulator. To analyse the optical and electrical properties of the proposed solar cell, several technological parameters such as work function and thickness of MoOx contact layer, intrinsic a‐Si:H band gap, interface recombination, series resistance, and temperature coefficient have been evaluated. It has been shown that higher work function of MoOx induces the formation of a favourable Schottky barrier height as well as an inversion at the front interface, stimulating least resistive path for holes. Utilising thinner MoOx layer implies reduced tunnelling of minority charge carriers, thus enabling the device to numerically attain 25.33% efficiency. With an optimised interface recombination velocity and reduced parasitic absorption, the proposed device exhibited higher Voc of 752 mV, Jsc of 38.8 mA/cm2, fill‐factor of 79.0%, and an efficiency of 25.6%, which can be termed as the harbinger for industrial production of next‐generation efficient solar cell technology. The 2‐D cross‐section view of the proposed device is illustrated in Figure 1A for which we have applied memory intensive numerical method based on the computation of Poisson, charge transport, and continuity equations in the Silvaco ATLAS module. To undertake in‐depth analysis of the proposed structure, a simple device based on MoOx/cSi wafer was first designed and simulated to understand the charge transport behaviour in such solar cells with CSC. Figure 1B shows the energy band diagram of the simple solar cell structure. Interface inversion is created at the interface due to Fermi level pinning indicating excess of hole carriers near the surface, which are ready be collected by anode terminal.