Study Of Surface Texturization On Mono‐crystalline Silicon

With world’s energy crisis increasing fiercely, solar energy has become the most potentialalternative energy in the future, and now the biggest problem is how to increase the photoelectricconversion efficiency of solar cell. Surface texturization of mono-crystalline silicon is the keytechnique to improve photoelectric conversion efficiency of solar cell. With texturization,pyramid structure was formed on the surface and light trapping effect was occurred whenmono-crystalline silicon was exposured to light, which reduced the reflectance of light andthereby improved the photoelectric conversion efficiency.The texturization technologies reported were mostly adding surfactant IPA in alkalinesolutions (NaOH, KOH, TMAH, etc.), which prepared low-reflection texturized surface withpyramid structure because of anisotropic etching to silicon. However, IPA is so expensive,low-boiling, and toxic, making the high production cost. Along with the too long etching time,the texturization technologies reported go against to the large-scale industrial application, sincethe high requirement of cost and time. Based on it, this paper aims to explore a kind oftexturization technology, which prepares low-reflection texturized surface with low cost andshort etching time.Using a self-made equipment, we first used single components of Na2CO3and NaHCO3asetching solution to texturize mono-crystalline silicon. Then, by setting optimized experimentalconditions, we prepared texturized surface in Na2CO3/NaHCO3mixed solution with differentproportions, time and temperature. Scanning electron microscope (SEM) characterized themorphology of texturized surface and UV-2500uv-vis spectrophotometer with an integratingsphere tested the reflectivity. Through analyzing the reaction mechanism, the results andconclusions followed:The lowest reflection loss of texturized surface in Na2CO3solution was15.78%, and usingNaHCO3solution to prepare texturized surface, the reflectivity was always higher than19.0%.The surface prepared by Na2CO3/NaHCO3mixed solution got the lowest reflection loss of13.24%. In the etching process, the OH-ion plays a key role, and CO32-and HCO3-have thesame effectiveness of IPA used in traditional texturization technologies. CO32-and HCO3-just act as new surfactant, promoting H2bubbles to depart from silicon surface and making the pyramidstructure more well-distributed. The optimum experiment conditions are10:1(mass ratio) ofNa2CO3/NaHCO3,90°C of temperature,10min of etching time.