Preparation And Research Of TCO/c-Si Heterojunction Solar Cells

In order to deal with the energy conservation and environmental protection requirements of industrial development,the development of clean energy is the general trend.As a kind of clean energy,solar power generation has developed rapidly in recent years.Because of its earliest research and abundant materials,silicon solar cells have mature manufacturing processes and occupy 90%of the photovoltaic market.At present,high-efficiency crystalline silicon solar cells mainly include:HIT?IBC?TOPcon?IBC-SHJ and DASH.These solar cells optimize the structure of solar cells from these aspects:carrier selection contact,contact passivation,reduction of light shading,etc.,and thus achieve higher efficiency.For a long time,TCO materials have been widely used in solar cells because of their excellent photoelectric properties.As a window layer of solar cells,how to improve the optical performance without compromising electrical performance has become a hot spot.It was found in research that TCO material not only has good photoelectric performance,but also is a high work function material.This paper mainly studies two transparent conductive films:IWO and ITOH,and uses these two materials for silicon heterojunction solar cells.By using the work function of the material,itself to form a band gap with the silicon material,selective transport of holes is achieved.The main research contents are as follows:1)IWO films were prepared by modulating the sputtering power and their effects on the properties of IWO films were analyzed.As the sputtering power is increased from 30W to 150W,the structure and morphology of the thin film changes less.The photoelectric characteristics are greatly affected by power,the average transmittance has decreased from 88.5%to 85.7%,and the resistivity has decreased from42.79×10-4 ?·cm to 4.3×10-4 ?·cm.The best mobility at 120 W was 47.2 cm2V-1s-1.The maximum value of the work function measured by the Kelvin probe was 4.9 eV.On this basis,the effects of different power deposition on the performance of IWO/c-Si heterojunction solar cells were studied.When the deposition power is 90W,the performance of the IWO/c-Si heterojunction solar cell is:Voc is 569.7 mV,Jsc is 38.22 mA/cm2,and the FF is 75.0%.Finally,a cell efficiency of 16.32%is obtained.2)We investigated the effects of hydrogen-doped ITO(ITOH)films prepared by RF magnetron sputtering on the performance of TCO/Si heterojunction solar cells.The results show that:hydrogen doping is more conducive to increase the fill factor(FF)of ITO Si heterojunction cells,up to 82%.Experimental data show that:ITO Si heterojunction cells optimum efficiency of 14.7%,which Voc reach 572 mV,Jsc was 36.5 mA/cm2,FF was 70.3%.ITOH/c-Si heterojunction cell efficiency is improved by 6.8%to 15.7%,where Voc reach 530 mV,Jsc was 38.1mA/cm2,FF was 77.9%.For single-layer films,as the annealing temperature rises,the sheet resistance of the ITOH film decreases monotonically,while ITO increases first and then decreases.The degree of crystallinity of the films was enhanced,and they all showed(222)preferential growth.At 300?,the optical performance of ITO film is better than that of ITOH film,and the optical band gap of ITO reached 3.93eV.At present,we have also made preliminary attempts on stacked ITO/ITOH/c-Si heterojunction cells.The stacked ITO/ITOH balances the performance of Voc and FF and achieves a battery efficiency of 17.5%.