Application Of O/M/O Composite Transparent Conductive Films In Solar Cells

In this thesis,ITO/Ag/ITO（IAI）and ITO/Ag/AZO（IAA）metal matrix composite transparent conductive films with better optical and electrical properties were fabricated by magnetron sputtering（PVD）and pulsed laser deposition（PLD）.And then a copper indium gallium selenide（CIGS）solar cell was prepared using a sputtering selenization method and an amorphous silicon（a-Si）solar cell was prepared by plasma enhanced chemical vapor deposition（PECVD）.The composite transparent conductive films were applied to copper indium gallium selenide and amorphous silicon solar cells.Copper indium gallium selenide（Cu（In,Ga）Se₂）thin films were fabricated using radio frequency magnetron sputtering from a single quaternary ceramic target followed by the rapid thermal annealing treatment.The target was made of Cu₂Se,Ga₂Se₃,and In₂Se₃ powder with the ratio of Cu:In:Ga:Se=20:17.5:7.5:55 wt%.By adopting a gradient sputtering power,i.e.,a constant 45 W for the first 120 minutes and a step power from 45 to 50 W for the last 30 minutes,the films had a Cu-poor smooth surface and showed favorable chemical stoichiometry.After selenization,the ratio of Cu/（In+Ga）was examined as about 0.80-0.95 and the ratio of Ga/（In+Ga）was about 0.20-0.30.CIGS thin film solar cells were prepared with the ITO/Ag/AZO sandwich structure as the electrode,then the IAA structures high transmittance and low resistance were fabricated through the pulsed laser deposition（PLD）technique combined with the RF magnetron sputtering technique These structures exhibited an extreme low sheet resistance about 7.26Ω/sq and a relative high transparency of96.53%at the wavelength of 550 nm.CIGS solar cells with the IAA electrodes exhibited a maximum power conversion efficiency of 5.61%under the standard AM1.5 global illumination with a light intensity of 100 mW/cm².An improvement of over 21%in short-circuit current density and a 9%increase in the energy conversion efficiency were achieved comparing with the ITO/Ag/AZO and ITO（360 nm）electrodes.A structure with dual p-layers（p-a-SiO_x:H/p-nc-Si O_x:H）was used as the window layer in thin film hydrogenated amorphous silicon（a-Si:H）p-i-n solar cells with SnO₂:F（FTO）as the front electrode.By this method,we introduced the high conductivity of p-nc-SiO_x:H layer with a higher optical band gap in a-Si:H solar cells.And the destabilized problems of Sn⁴⁺in FTO with a high-flux hydrogen plasma have been solved during the growth of p-nc-SiO_x:H.The dual p-layers in a-Si:H solar cells exhibited the properties that enhance the hole transmission and reduce the recombination current.The properties of a-Si:H solar cells were controlled by different thicknesses of p-a-SiO_x:H and p-nc-SiO_x:H.The p-nc-SiO_x:H film in dual p-layers could increase the built-in potential in a-Si:H solar cells to achieve higher open circuit voltage(V_oc)and short-circuit current density(J_sc).Finally,the conversion efficiency of the a-Si:H solar cell with p-a-SiO_x:H（7 nm）/p-nc-SiO_x:H（7 nm）dual p-layers was enhanced by 12.90%.ITO/Ag/ITO（IAI）trilayer films were deposited on glass substrates by the radio frequency magnetron sputtering at room temperature.A high optical transmittance over 94.25%at the wavelength of 550 nm and an average transmittance over the visual region of 88.04%were achieved.The calculated value of figure of merit（FOM）reaches 80.9×10^-3Ω^-11 for IAI films with a 15-nm-thick Ag interlayer.From the morphology and structural characterization,the IAI films could show an excellent correlated electric and optical performance if Ag grains interconnect with each other on the bottom ITO layer.These results indicate that IAI trilayer films,which also exhibit the low surface roughness,have a potential application in optoelectronic devices.