Research On The Thin-film(P)/Crystal-silicon(N) Hetero-junction With Intrinsic Amorphous Silicon Passivation Layer Solar Cells

Hetero-junction with intrinsic thin-layer?HIT?solar cells combining high conversion efficiency of crystalline silicon cells and simple process of thin-film silicon cells become a hot topic in the world of PV field.Recently,the world's highest HIT conversion efficiency level of 25.6%has been achieved by Japan Panasonic,which was obtained by the back contact technology.With a area of 143.7cm² and a thickness of less than 100?m,HIT cells show its great potential to improve efficiency and reduce cost.However,the theoretical basis and industrialization level of HIT cells are very backward in our country.The highest efficiency of the cell is only 17.36%?1.2cm²?.For the above,this paper mainly focused on the core technology of hetero-junction cells carries out the following tasks:?1?The impact of the hydrogen treatment time,i-layer thickness and depositional condition on the properties of hetero-junction solar cells were investigated.Studies have shown that:under the H treatment time of 50s,the i-layer thickness of 5nm,the discharge power density of 50mW/cm²,the deposition pressure of 0.3torr,the silane concentration of 8%and the frequency of VHF of 75MHz,the passivation effect of intrinsic layer was best.At the said condition,an efficiency of 9.106%with the open-circuit voltage of 673mV was obtained.?2?The influence of annealing treatment upon hetero-junction soalr cells was introduced.The conclusions are as follows:the V_oc and I_sc of the hetero-junction cells?without intrinsic layer?all increased firstly and then decreased with increasing annealing time.They both obtained a maximum at the annealing time of 60min and30min respectively,the?increased at 60min.This can be explained that annealing treatment can produce the heat effect inside the battery,which can reduce the interface defect density of states and optimize the structure of thin film.At the same time,annealing treatment can also recombine each thin film,which can improve the overall contact and the performance of the cell.An optimized annealing time?60min?was used in hetero-junction cells?with intrinsic layer?.It can improve the overall contact because of the heating of the aluminum back electrode,which can decrease R_s and increase I_sc.However,the annealing time was too long for this cell.It increased the crystallization rate of intrinsic hydrogenated amorphous silicon?i-a-Si:H?thin film and added the amount of precipitation of hydrogen in this layer,which can not saturate the interface dangling bonds effectively and influenced the passivation effect of the intrinsic layer thin film.?3?In order to improve the fill factor,preparation technology of several kinds of hetero-junction cells was compared.1)The p-type window layer and the front ITO electrode was deposited in sequence on the positive side of c-Si,then the aluminum back electrode was deposited on the back side of c-Si.2)Changed the sputtering power of the 1)cell's ITO electrode.3)Before depositing the 1)cell's aluminum back electrode,a thickness of 50nm ITO thin film was deposited on the back side of c-Si substrate and formed a double-sided ITO battery.4)Changed the preparation order of the 1)cell's electrode and deposited the aluminum back electrode before the ITO front electrode.5)Increased the 1)cell's area to 2?2 cm² and introduced aluminum gate lines on the ITO electrode.After attempts and comparative analysis of the above five kinds of craft,the hetero-junction cells which adopted the first preparation process has the toppest FF and the best performance.