The Study Of Optoelectronics Performance On Cu（InGa）Se₂Thin Film Material And Device With Variable Bandgap

The large-scale fabrication and application of bandgap engineering have becameone of key issues in the field of solar cells. Sputtering deposition techniques aresuitable for large-scale and industrial production. Therefore, this paper mainlyfocuses on how to prepare high quality Cu(In_1-xGa_x)Se₂（CIGS） alloy films withvariable bandgap by using sputtering technique. And the properties of these filmsare deeply studied. Meanwhile, the effects of the characteristics parameters withdifferent bandgaps profile on the device performances are also systematicallyresearched. Finally, it is studied how to use rapid thermal annealing （RTA） processto improve device performance.By adjusting deposition temperature, rate of rotation, the deposition rate and time tocontrol the ratio of Ga/（In+Ga） during the deposition process, we successfullyfabricated the CIGS solar cell with variable band gap by using Cu-Ga （28at.%） alloytarget and an In target acting as sputtering source. For the CIGS solar cell with the“” grading profile, the optimal opto-electric conversion efficiency of8.83%(J_SC=24.3mA/cm2,V_oc=600mV, FF=60.5%) is obtained. For the solar cell with the“V” grading profile, the optimal opto-electric conversion efficiency of12.1%(J_SC=26.8mA/cm2,V_oc=630mV,FF=72.1%) is obtained under AM1.5G.The interfaces characteristics of CIGS cells with “V” profile are studied by theapproach combined X-ray photoelectron spectroscopy （XPS） with Rutherford backscattering （RBS）. The results showed that its structure can be divided into nine layerssuch as AZO/ZnO/Interface Mixed layer/CdS/Interface mixed layer/CIGS1/CIGS2/MoSe₂/Mo.Screen printing suitable for large scale and industrial production is developed toprepare front electrode of CIGS solar cells. The front electrode fabriation process insilicon solar cells is transplant into CIGS solar cells by low temperature slurry. Theeffects of different components, drying temperature and time parameters in slurry on the device performance are systematically studied. At the same time, we compare theeffect of vacuum evaporation on CIGS solar cell performance and stability withscreen printing.The impact mechanism of RTA on CIGS device performance is systematicallystudied. RTA can effectively eliminate the residual Cu2-xSe compounds in CIGS thinfilm，improve the crystallinity of the thin film, reduce the light loss of front surface,improve the CdS film on the blue response, increase the roughness of the frontsurface and reduce the defect states in CIGS layer. Meanwhile, RTA also optimizesthe atomic composition ratio in the multilayer film and adjusts the mixing zone atMo/CIGS interface.