COMPOSITE SILICON SOLAR CELL EFFICIENCY SIMULATION STUDY; SENSITIVITY TO THE ABSORPTION COEFFICIENTS AND THE THICKNESS OF INTRINSIC ABSORBER LAYER

Abstract: In this paper, two silicon solar cells p+-ii-n+ with homogenous and heterogeneous intrinsic absorber layers based on hydrogenated amorphous-nanocrystalline-microcrystalline silicon (a-Si:H/nc-Si:H/?c-Si:H) have been studied by computer modeling and simulation program (AMPS-1D - Analysis of Microelectronic and Photonic Structures). Various factors that affect cell efficiency performance have been studied such as layers absorption coefficients, band gap and layer thickness up to 1200nm. It was found that in the case of standard solar cell conditions a layers absorption coefficient has a major contribution to solar cell performance according to measurement on the actual solar cell samples. It is demonstrated that, for homogenous a-Si:H/nc-Si:H intrinsic absorber layer with constant crystal fraction of Xc=30% cell efficiency is higher than in case of heterogeneous intrinsic absorber layer which contains of arbitrary crystal fractions depending of absorber layer thickness. Second case scenario of silicon thin film composite structure is more common in solar cells production according to PECVD and HWCVD deposition technique proven by earlier X-ray diffraction and high resolution electron microscopy measurements.

Keywords: Amorphous-nanocrystalline-microcrystalline silicon, absorption coefficients, crystal fraction, efficiency.