Passivation of all-angle black surfaces for silicon solar cells

Abstract

Abstract-Optical losses at the front surface of a silicon solar cell have a significant impact on efficiency, and as such, efforts to reduce reflection are necessary. In this work, a method to fabricate and passivate nanowire-pyramid hybrid structures formed on a silicon surface via wet chemical processing is presented. These high surface area structures can be utilised on the front surface of back contact silicon solar cells to maximise light absorption therein. Hemispherical reflectivity under varying incident angles is measured to study the optical enhancement conferred by these structures. The significant reduction in reflectivity (<2%) under low incident angles is maintained at high angles by the hybrid textured surface compared to surfaces textured with nanowires or pyramids alone. Finite Difference Time Domain simulations of these dual micro-nanoscale surfaces under varying angles supports the experimental results. In order to translate the optical benefit of these high surface area structures into improvements in device efficiency, they must also be well passivated. To this end, atomic layer deposition of alumina is used to reduce surface recombination velocities of these ultra-black silicon surfaces to below 30 cm/s. A decomposition of the passivation components is performed using capacitance-voltage and Kelvin Probe measurements. Finally, device simulations show power conversion efficiencies exceeding 21% are possible when using these ultra-black Si surfaces for the front surface of back contact silicon solar cells.

Development of efficient solar cells with the use of multifunctional multitextures

“…However, the above technologies employ sophisticated equipment that predetermines high cost of the resulting product. It is possible to reduce the cost of SC along the way of forming the layers of porous silicon (PS) of the "Black Si" type by using electrochemical etching [3,4]. All these factors need to be considered when choosing the technological method for obtaining the front surface of SC.…”

Graphene as transparent electrode in Si solar cells: A dry transfer method

“…[6][7][8] On the other hand, as the alternative transparent electrode, graphene transfer on cell has unique advantages such as low cost, high performance and simple process. Therefore, many studies focus on graphene/Si schottky junction solar cell with wet transfer graphene process in recent years.…”

Investigation of effective near-infrared light-trapping structure with submicron diameter for crystalline silicon thin film solar cells

“…Many researchers have reported that SiNW arrays have high light absorptance and are promising as absorber layers for solar cells. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, despite their excellent optical advantages, the conversion efficiency of SiNW-based solar cells is yet insufficient because of serious surface recombination due to their high surface area-to-volume ratio. Accordingly, it is necessary to obtain high absorptance with short wires from the perspective of not only an etching margin but also surface recombination.…”