INFLUENCE OF INTRINSIC LAYER THICKNESS IN THE EMITTER AND BSF OF HIT SOALR CELLS

摘要

A symmetric structure has been generally used to fabricate heterojunction with intrinsic thin layer(HIT) solar cells, i.e. hydrogenated amorphous silicon (a-Si:H) forms the emitter (i-p stack) and the back surface field(BSF) (i-n stack), and transparent conductive oxide (TCO) covered with metallic electrodes is used on either side. Inthis contribution, we present the influence of the intrinsic a-Si:H layer thickness in both the emitter and BSF on thepassivation and solar-cell performance. Using a thicker intrinsic a-Si:H layer in the emitter results in a longereffective minority carrier lifetime, indicating a better passivation of the a-Si:H/c-Si interface and leading to a higheropen-circuit voltage (V_(oc)). In the BSF, thinner or even no intrinsic a-Si:H can be used to increase FF. In both theemitter and BSF, the fill factor (FF) is strongly related to the intrinsic a-Si:H layer thickness. In our investigation, theshort circuit current density (J_(sc)) does not change obviously with the variation of the intrinsic a-Si:H layer thickness.In the case that a full metal contact is used on the BSF side, the solar cell without back TCO shows a betterperformance. An efficiency of 17.5% is obtained in the flat HIT solar cell without intrinsic a-Si:H passivating layerand TCO on the side of BSF.