Absorption enhancement in amorphous Si by introducing RF sputtered Ti intermediate layers for photovoltaic applications

Abstract

In this paper, embedded Amorphous-Silicon (a-Si) and Titanium (Ti) ultrathin-films forming a multilayer structure is proposed as a new efficient absorber material for thin-film solar cells (TFSCs). Promising design strategy based on combining FDTD (Finite Difference Time Domain) with Particle Swarm Optimization (PSO) was adopted to identify the a-Si/Ti multilayer geometry offering the highest Total Absorbance Efficiency (TAE). It is found that the optimized design can serve as an effective absorber, yielding superb TAE exceeding 80%.The optimized a-Si/Ti multilayer was then elaborated by successive growth of a-Si and Ti ultrathin layers using RF magnetron sputtering technique. The sputtered a-Si/Ti thin-film was characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and UV-Visible absorption spectroscopy. Measurements showed a unique optical behavior, promoting broadband absorbance over the visible and even NIR spectrum ranges. In particular, the prepared a-Si/Ti absorber exhibits an optical band-gap of 1.36 eV, which is suitable for photovoltaic applications. A performance assessment of the elaborated absorber was investigated by extracting I-V characteristics and electrical parameters under dark and 1-sun illumination. It is revealed that the proposed absorber demonstrates outstanding electrical and sensing performances. Therefore, promoting enhanced resistive behavior and light-scattering effects, this innovative concept of optimized a-Si/Ti multilayer provides a sound pathway for designing promising alternative absorbers for the future development of a-Si-based TFSCs.