Numerical Simulation and Experiment of a High-Efficiency Tunnel Oxide Passivated Contact (TOPCon) Solar Cell Using a Crystalline Nanostructured Silicon-Based Layer  
[PERSON]  
1 Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Gyeonggi-do, Korea; [EMAIL_ADDRESS] (M.Q.K. ); [EMAIL_ADDRESS] (M.A.Z. ); [EMAIL_ADDRESS] (D.P.P)  
[PERSON]  
2 Department of Physics, Lahore Campus, COMSATS University Islamabad, Lahore 54000, Pakistan; [EMAIL_ADDRESS]  
[PERSON]  
1 Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Gyeonggi-do, Korea; [EMAIL_ADDRESS] (M.Q.K. ); [EMAIL_ADDRESS] (M.A.Z. ); [EMAIL_ADDRESS] (D.P.P)  
[PERSON]  
progressed cell design such as the interdigitated back contact (IBC) [14], TOPCon solar cells hold the full area contact, excluding the comparatively complex procedure for localized contacts. Through dominant equipment suppliers, new TOPCon processes have developed and matured, representing a considerable potential towards mass production [15]. The developing TOPCon solar cells have been analyzed primarily under experimental techniques and to experience the extensive knowledge of the critical parameters which influence the device's performance, an organized numerical inspection is necessary. Such vital parameters include the thickness as well as the characteristics of the silicon oxide (SiO\({}_{2}\)) layer, quality and the concentration of doping in the nc-SiO\({}_{\text{x}}\) layer, and the interface characteristics, in addition to their combination thereof. Through simulation, [PERSON] et al. have provided an acceptable model to evaluate the achievement of TOPCon solar cells displaying various n\({}^{+}\)-Si materials (polycrystalline silicon as well as amorphous silicon) [16; 17]. They focused on the carrier-selective electron contacts with tunnel oxides as well as identified what sort of material structures are appropriate in favor of a TOPCon solar cell. In the present study we examined the routes to accomplish this, together with an outstanding carrier collection as well as surface passivation of a TOPCon solar cell by employing the simulation tool of the AFORS-HET (automat for simulation of heterostructures) software and through experiments. The main factor which limited our efficiency was the rear side contact because in the case of the front side contact it gave an exceptional passivation junction characteristic to the solar cells. The rear side layer should be transparent to provide a superior passivation and an excellent charge carrier transfer, while parasitic absorption losses should be minimized. We report on an unconventional rear side passivating electron contact which minimized absorption losses and ameliorated the transparency by substituting a doped poly-Si layer. Herein, we propose a TOPCon solar cell comprising of a SiO\({}_{\text{x}}\)/nc-SiO\({}_{\text{x}}\)(n) stack on the rear end. To reduce the optical and parastical absorption, nc-SiO\({}_{\text{x}}\)(n), a wide bandgap material, was developed to replace the doped poly-Si. The carrier selectivity, surface passivation, optical transmission, and electrical characteristics could then be improved by the nc-SiO\({}_{\text{x}}\)(n) layer, which is crucial for device functionality, while changing the oxygen content may alter the optical and electrical properties. This study on TOPCon cells aimed to propose the creation of a TOPCon silicon solar cell system with a high performance and suggests an alternative framework that can be employed in the industry by using poly-Si in a TOPCon cell structure. Thus, our proposed TOPCon cell arrangement provides several advantages as compared to the conventional cell. Figure 1a,b shows a schematic of our proposed TOPCon solar cell.