Large-size multi-crystalline silicon solar cells with honeycomb textured surface and point-contacted rear toward industrial production

In this paper, we present a multi-crystalline solar cell with hexagonally aligned hemispherical concaves, which is known as honeycomb textured structure, for an anti-reflecting structure. The emitter and the rear surface were passivated by silicon nitride, which is known as passivated emitter and rear (PERC) structure. The texture was fabricated by laser-patterning of silicon nitride film on a wafer and wet chemical etching of the wafer beneath the silicon nitride film through the patterned holes. This process succeeded in substituting the lithographic process usually used for fabricating honeycomb textured structure in small area. After the texturing process, solar cells were fabricated by utilizing conventional fabrication techniques, i.e. phosphorus diffusion in tube furnace, deposition of anti-reflection film and rear passivation film by chemical vapor deposition, front and rear electrodes formation by screen printing, and contact formation by furnace. By adding relatively small complicating process to conventional production process, conversion efficiency of 19.1% was achieved with mc-Si solar cells of over 200 cm2 in size. The efficiency was independently confirmed by National Institute of Advanced Industrial Science and Technology (AIST).