Electrical Properties of 10x10 cm~2 HIT Solar Cells with Screen-printed Metal Grids Manufactured on Textured p-type mc-Si Substrates

摘要

In the present study we have investigated the electrical properties of 10x10 cm~2 HIT solar cells with low temperature ( < 250°C) screen-printed metal grids manufactured on p-type mc-Si substrates. The HIT solar cells consist of a grid/ITO/(n)a-Si:H/(i)a-Si:H/(p)mc-Si/Al structure. The bulk lifetime is improved by the SiN_x deposition and subsequent firing, as shown by Quasi-steady-state lifetime measurements. The substrates are subject to an acid texturing. The a-Si:H emitter and intrinsic buffer layers are deposited with a standard PECVD setup at substrate temperatures below 250°C. An indium tin oxide layer is sputtered as a transparent conductive anti-reflection coating layer under conditions optimized according to the internal quantum efficiency characteristics. The front and back sides of the solar cells are metallized by low temperature screen-printing and evaporated Al, respectively. The series and parallel resistances are about 0.2 or less and 270 Ω or higher, respectively, as deduced from Ⅰ-Ⅴ and C-V measurements. Thermographic images show that there are no local shunts over the entire solar cell area except at the wafer edge. The resulting efficiency is up to 12.9% for the solar cells prepared on standard block cast mc-Si substrates without back surface field.