Controlling a crystalline seed layer for mirocrystalline silicon oxide window layer in rear emitter silicon heterojunction cells

Abstract

Remarkable progress has been made in the improvement of rear-emitter silicon heterojunction (RE-SHJ) solar cells with the use of very thin n-type front contact layers. However, further reducing the thickness of the front window layers while maintaining high conductivity for mitigating the parasitic absorption and carrier collection loss has proven challenging. In this study, we implement controlling a seed layer for achieving ultra-thin, high crystalline and conductivity of n-type hydrogenated microcrystalline silicon oxide (n-mu c-SiOx:H) front window layer in RE-SHJ solar cells. By using a seed layer, the crystallinity confirmed by Raman and TEM measurements, and the conductivity of the n-mu c-SiOx:H front layers are significantly enhanced compared with that without using the seed layer. This leads to a remarkable increase in the open-circuit voltage (V-oc) by 6 mV and fill factor (FF) by 4.11% while maintaining a high short-circuit current density (J(sc)) in range of 38 mA/cm(2). A high cell performance of 21.1% is obtained with the use of an optimised seed layer.