Study On Preparation And Performance Of Monocrystalline Black Silicon Using Ag-Assisted Chemical Etching

Photovoltaics is the most practical new energy in the foreseeable future. Crystalline silicon solar cell has dominated the market of photovoltaics in the recent decades. The limiting factor for the application of photovoltaic is the low conversion efficiency of solar cells. Increasing the usage of incident light is one of the ways to effectively increase conversion efficiency of solar cells. Compared with traditional crystalline silicon solar cells, black silicon solar cells can effectively reduce the front reflection of solar cells. Now, it has been considered as the most important technique to achieve high conversion efficiency solar cells and has great application prospect in the future industry.This work focuses on the research of black silicon solar cells using Ag metal-assisted etching to grow nanopores and fabricate black silicon solar cells. We have studied the influence of reaction time on the nanostructure morphology and reflectivity. We found that increasing the reaction time could enlarge the length of nanopores and reduce the front reflectivity to less than 3%. However the increase of the length of nanopores could result in the enhancement of surface recombination in black silicon solar cells reducing the minority lifetime of black silicon solar cells, the open-circuit voltage as well as the short-circuit current, leading to deteriorated electrical performance.This work restructured the surface modification of fabricated nanostructure using NH4OH solution to address the problem of surface recombination in black silicon solar cells. We studied the influence of NH4OH solution to different nanostructure. The research demonstrated that the NH4OH solution can effectively reduce the surface ratio of nanostructure, reduce surface recombination of nanostructure and increase the minority lifetime of nanostructure to 42.04μs. With the increase of the etching time in NH4OH solution, the minority lifetime in black silicon solar cells increase, with the open-circuit voltage of 602m V comparable to pyramid texture. At the same time, the short-circuit current was increased as well. Because of the increase of reflectivity of etched solar cells, the solar cell performance is best with etching time of 10 min. The short-circuit current has increased 0.9mA/cm2 compared with pyramid solar cells. The conversion efficiency has increased 0.3%, demonstrating the potential of the black solar cells in increasing the conversion efficiency of crystalline solar cells.Black solar cell can reduce the surface reflectivity of solar cells. But the internal quantum efficiency of solar cells is low in short-wavelength range unable to effectively utilized solar energy. Therefore, this work adopted melting method to grow Eu2+:ZnCdSxsemiconductor microcrystal and studied their light-emitting property hoping that it could be applied in industry. Our research showed that the size and the energy band gap of semiconductor microcrystal could get controlled by adjusting the annealing time realizing ideal light-emitting property and reaching quantum efficiency of more than 20%. At the same time, we have cooperated with photovoltaic companies to get the effective parameters predicting the direction of next research.