Numerical Analysis of Metal Poly-Si Contact in TOPCon Solar Cells Through Device Simulations Using Sentaurus TCAD

Tunnel oxide passivated contact (TOPCon) is an emerging technology for highly efficient with excellent passivation photovoltaic (PV) devices. However, a standard TOPCon cell suffers from insufficient efficiency gain and recombination losses due to the presence of a direct metal-crystalline silicon contact. Therefore, bifacial configurations with advanced passivated structures have been considered in this research work. In this work, the performance of bifacial TOPCon device with double-side (DS) TOPCon structures, integrated with poly-Si, is explored and modeled using Sentaurus TCAD software. The reported study develops a framework to obtain state-of-the-art bifacial TOPCon structures with optimized input parameters and considering tunneling structures. The impact of collective front/rear SiNx layer thickness (from 50 to 100 nm) and p+ poly Si thickness (from 20 to 100 nm) on the performance of bifacial-DS TOPCon solar is studied and analyzed for optimized PV performance. This research study reveals that optimizing the p+ poly-Si thickness enhances carrier collection with minimal bulk recombination losses. The PV performance of DS structure indicates that incorporating DS carrier selective contacts increases the PV efficiency. Also, the detailed analysis of bifacial TOPCon structure reveals that suppressing the recombination by incorporating tunneling structures on both sides can be the key strategy to improve PV performance with an optimized efficiency of 26.3%. The reported study set a clear direction for higher PV performance by incorporating a tunneling approach in next-generation c-Si solar cells at low cost.