Opto-electrical modelling and optimization study of a novel IBC c-Si solar cell

Abstract

Interdigitated back contact (IBC) crystalline silicon (c-Si) solar cells are attracting a lot of attention because of their capability to reach world record conversion efficiency. Because of the relatively complex contact pattern, their design and optimization typically require advanced numerical simulation tools. In this work, a TCAD-based simulation platform has been developed to account accurately and in detail the optical and passivation mechanisms of front texturization. Its validation has been carried out with respect to a novel homo-junction IBC c-Si solar cell based on ion implantation and epitaxial growth, comparing measured and simulated reflectance, transmittance, internal quantum efficiency, external quantum efficiency spectra, and current density-voltage characteristics. As a result of the calibration process, the opto-electrical losses of the investigated device have been identified quantitatively and qualitatively. Then, an optimization study about the optimal front surface field (FSF) doping, front-side texturing morphology, and rear side geometry has been performed. The proposed simulation platform can be potentially deployed to model other solar cell architectures than homo-junction IBC devices (e.g., passivated emitter rear cell, passivated emitter rear locally diffused cell, hetero-IBC cell). Simulation results show that a not-smoothed pyramid-textured front interface and an optimal FSF doping are mandatory to minimize both the optical and the recombination losses in the considered IBC cell and, consequently, to maximize the conversion efficiency. Similarly, it has been showed that recombination losses are affected more by the doping profile rather than the surface smoothing. Moreover, the performed investigation reveals that the optimal FSF doping is almost independent from the front texturing morphology and FSF passivation quality. According to this result, it has been demonstrated that an IBC cell featuring an optimal FSF doping does not exhibit a significant efficiency improvement when the FSF passivation quality strongly improves, proving that IBC cell designs based on low-doped FSF require a very outstanding passivation quality to be competitive. Deploying an optimization algorithm, the adoption of an optimized rear side geometry can potentially lead to an efficiency improvement of about 1% abs as compared with the reference IBC solar cell. Further, by improving both emitter and c-Si bulk quality, a 22.84% efficient solar cell for 280-μm thick c-Si bulk was simulated.

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

“…Accurate opto‐electrical simulations of poly‐poly solar cells are performed using a modelling framework based on TCAD Sentaurus,combining thin film optics and opto‐electrical properties, such as free carrier absorption. The simulated structure is reported in Figure C using experimentally extracted wavelength‐dependent refractive index of poly‐Si .…”

Transparent silicon carbide/tunnel SiO2 passivation for c‐Si solar cell front side: Enabling Jsc > 42 mA/cm2 and iVoc of 742 mV

“…For the light trapping model, we assumed a substrate thickness of 170 μm. Lastly, potential short‐circuit current densities were calculated by means of Monte Carlo ray tracing technique in combination with the transfer matrix method boundary conditions within Sentaurus TCAD . Models and parameters are detailed elsewhere .…”

Efficient Low-Cost IBC Solar Cells with a Front Floating Emitter: Structure Optimization and Passivation Layer Study

“…Interdigitated back contact (IBC) crystalline silicon solar cells are attracting much attention in the solar cells research society due to their potential to achieve a high power conversion efficiency by eliminating the shading losses altogether through putting both contacts on the rear of the cells [1,2]. Many institutes such as Fraunhofer ISE, ECN, and ISC-Konstanz are now working on IBC solar cells and their commercialization [3,4].…”