Influence of patterning the TCO layer on the series resistance of thin film HIT solar cells

Abstract

Thin HIT solar cells combine efficient surface passivation and high open circuit voltage leading to high conversion efficiencies. They require a TCO layer in order to ease carriers transfer to the top surface fingers. This Transparent Conductive Oxide layer induces parasitic absorption in the low wavelength range of the solar spectrum that limits the maximum short circuit current. In case of thin film HIT solar cells, the front surface is patterned in order to increase the effective life time of photons in the active material, and the TCO layer is often deposited with a conformal way leading to additional material on the sidewalls of the patterns. In this article, we propose an alternative scheme with a local etching of both the TCO and the front a-Si:H layers in order to reduce the parasitic absorption. We study how the local resistivity of the TCO evolves as a function of the patterns, and demonstrate how the increase of the series resistance can be compensated in order to increase the conversion efficiency.

Effect of ZnO‐based TCO on the performance of a‐Si H(n)/a‐Si H(i)/c‐Si H(p)/Al BSF(p+)/Al heterojunction solar cells

“…The c‐Si layer will thus absorb more incident light and J SC will consequently increase. Ability of TCO layers to behave as anti‐reflecting coatings has been reported in earlier multi‐layer solar cells . The simulated J–V plots are shown in Figure for cells with and without ZnO layer.…”

“…The report focused on experimental deposition and characterization issues but did not extend the study to photovoltaic applications. Inclusion of ITO‐based TCO in a‐Si:H solar cells was simulated as described earlier , and the TCO showed enhanced absorption by behaving as anti‐reflecting coating (ARC). Unlike earlier studies, the present work specifically describes how ZnO‐based TCO films deposited onto silicon wafers may affect the photo‐voltaic performance of the solar cell.…”

Emitter layer optimization in heterojunction bifacial silicon solar cells

“…The authors of Ref. [4] employed a modeling approach to optimize the device structure and thickness of silicon heterojunction solar cells with TiO 2 as a carrier-selective interface to achieve excellent performance, even with thin Si and to reduce the material cost of Si photovoltaics. Lower parasitic absorption in the transparent conducting oxide layer (TCO) of a thin HIT solar cell with a patterned TCO layer can enhance conversion efficiency at the price of a different front contact design.…”