Thermal curing of interface defects at a-si:H/c-Si in heterojunction with intrinsic thin layer (HIT) solar cell processing

Abstract

This study explores the use of thermal treatment to recover defects at the a-Si:H/c-Si interface caused by transparent conductive oxide (TCO) deposition, improving passivation by diminishing interface defect density (D_it). A 200 °C thermal treatment enhanced HIT solar cell performance, increasing the effective bulk lifetime to 1.1 ms at a minority carrier density of 1.0 × 10¹⁵ cm⁻³. Key performance metrics improved, including J_sc (from 38.70 to 38.88 mA/cm²), V_oc (from 727 to 730 mV), FF (from 75.50 % to 77.82 %), and efficiency (from 21.27 % to 22.09 %). AFORS-HET simulations showed that D_it must be less than 1 × 10¹¹ cm⁻² eV⁻¹ for optimal efficiency. The best solar cell performance, achieved in simulations, included J_sc of 37.71 mA/cm², V_oc of 716.8 mV, FF of 83.50 %, and efficiency of 22.57 % at D_it of 1 × 10⁹ cm⁻² eV⁻¹. This combined approach offers insights into defect management for solar cell technology.