Our research on the TOPCon solar cells aimed to (a) demonstrate a mechanism for enhancing cell performance in a TOPCon structure; (b) achieve an efficiency exceeding 27% utilizing the TOPCon cell configuration; (c) conduct extensive research on high-quality passivating contacts, such as stacks of nc-SiO\({}_{\text{x}}\)(n)/SiO\({}_{\text{x}}\) contacts, which are at the cutting edge in the latest photovoltaic (PV) research; (d) establish a systematic experimental and simulation procedure for the TOPCon cell; and (e) propose a method of increasing the performance of TOPCon cells. This unconventional structure contains a thermally grown thin silicon oxide layer (SiO\({}_{2}\)) on both sides of the c-Si wafer, with a surface covered by a phosphorus-doped nanocrystalline silicon oxide (nc-SiO\({}_{\text{x}}\)) on both sides. The technique we used for the fabrication was a plasma-enhanced chemical vapor deposition (PECVD) for the synthesis of the nc-SiO\({}_{\text{x}}\) layer. Furthermore, a wide thermal processing window helped in improving the temperature stability due to the existence of a thermally fabricated SiO\({}_{2}\) layer. The passivation properties were studied by varying the annealing temperature and fixing the thickness of SiO\({}_{2}\). The influence of the forming gas annealing (FGA) was also investigated. Moreover, in the experiment, our research concentered on the experimental designs of the nc-SiO\({}_{\text{x}}\) layer to describe the physical mechanisms for improvement and optimization of the passivation characteristics of the symmetric structures, by employing a quasi-steady-state photoconductance (QSSPC) measurement system. As far as a simulation is concerned, we accept the fundamental findings deduced by [PERSON], and our study can be considered as an extension of their prior published works. The uniqueness of our work lies in acknowledging the consequences of the elaborated parameters on the complete device performances, including for instance, the various thickness and work function of an oxide layer, the doping of nc-SiO\({}_{\text{x}}\), bulk defect density, rear SRV, interface-states density (D\({}_{\text{ht}}\)) as well as pinhole density through the oxide (D\({}_{\text{ph}}\)). SRV refers to the charge carriers that generated a loss that would have been imparted to the voltage or current which the cell could generate. The recombination mainly takes place in the surface and bulk region [18] and minimization is required on both the bulk recombination and surface recombination, to collect the maximum photo-generated carriers, which may be accomplished when the generated carriers are under their diffusion length. As compared to bulk recombination, surface recombination [19] needs extra consideration for numerous silicon devices on account of it enhancing the surface-to-volume ratio [20]. The parameters which influence the recombination are mentioned here; the effective minority carrier lifetime (\(\tau_{\text{eff}}\)), and SRV as well as the emitter recombination current (J\({}_{\text{oo}}\)). The effective lifetime can be divided based on location, bulk lifetime (\(\tau_{\text{b}}\)), and surface lifetime (\(\tau_{\text{s}}\)). These two terms are related by an inverse addition, as mentioned in Equation (1). The effective carrier lifetime is conveyed as a function of surface recombination velocity, as depicted in Equation (2). Here, W represents the wafer thickness, and D represents the diffusion constant of minority charge carriers [21; 22; 23]:  
\[\frac{1}{\tau_{\text{eff}}}=\frac{1}{\tau_{\text{b}}}+\frac{1}{\tau_{\text{s}}} \tag{1}\]  
\[\text{S}=\frac{\text{W}}{2\Big{(}\tau_{\text{s}}-\frac{1}{\text{D}}\big{(} \frac{\text{w}}{\pi}\big{)}^{2}\Big{)}} \tag{2}\]  
Additionally, our proposed simulation schemes for an optimized design of the tunnel oxide as well as the nc-SiO\({}_{\text{x}}\) layer contribute to a low tunneling resistance as well as high V\({}_{\text{oc}}\).