Design And Fabrication Of Absorbing Layer Of Vertical Nanowire Structure Solar Cell

In order to increase the photoelectric conversion efficiency of compound copper,zinc,tin and sulfur（CZTS）solar cells,nanostructures were applied to P-type absorption layer semiconductor materials.The advantages of nanowire structure solar cells over thin film solar cells were discussed by simulation and analysis of finite difference time domain（FDTD）.In this paper,single-phase crystallized CZTS absorbing layer films were prepared by two-step electrochemical deposition and high temperature vulcanization heat treatment,and nanowire absorbing layer structures perpendicular to the substrate were prepared on Mo/SiO₂ using plasma etching nanocolumns and through-hole anodic alumina（AAO）as templates,respectively.The results show that copper-zinc and copper-tin films were deposited by two-step electrodeposition.When the deposition potential and time were-1.2V,600s and-0.7V,10s respectively,the composition ratio of the prefabricated layer was 2:1:1.The single-phase CZTS absorbing layer was obtained after sulfurization treatment at 550 C for 50 minutes in sulfur atmosphere.The composition ratio of CZTS elements after sulfurization treatment was close to 2:1:1:4.Next,CZTS nanowires were fabricated by nano-pillar and nano-pore template methods,respectively.Polystyrene microspheres as masks and inductively coupled plasma etching（ICP）were used to fabricate vertical Mo/SiO₂ nanowire substrates,and the CZTS absorption layer with a diameter of 650 nm was electrodeposited on this substrate.Another method was to prepare nanoporous CZT nanowires with a diameter of 75 nm by secondary anodic oxidation.The CZT precast layer was electrochemically deposited in the pore.The absorption layer of CZTS nanowires with a diameter of 100 nm was obtained by sulfidation heat treatment.Compared with the two methods,the CZTS nanowires with nanopillars as templates had better perpendicularity to the substrate,but the distance between nanowires decreases or even disappears completely during vulcanization.In the preparation of CZTS nanowires with nanopore as template,AAO template was removed first,and then sulfurized annealing could avoid the fracture of nanowires.A few collapses occurred because the nanowires lost the support of AAO template.The nanowire structure obtained by two methods could reduce surface reflection and increase light absorption.