Investigation On The Fabrication And Performance Of Antimony Sulfide-Based Solar Cells

Energy has taken a vital strategic position in Chinese national economy.As stepped into the new millennium,our country has yet suffered the sharp conflict of imbalanced energy sources supplies and demands,which as a result of an unoptimized energy structure.In this case,it is a priority to build an energy system with diverse origins along with superior cost performances.In the journey of exploring energy sources,photovoltaic has been characterized as"environmentally friendly"or"zero pollution",thus elected to be the most promised new energy technology that has the ability to substitute fossil fuels.Among photovoltaic materials,metal chalcogenide semiconductor compounds can never draw enough attention.Antimony sulfide(Sb2S3),as we investigated in this thesis,has remarkable PV properties and wonderful stability in both moisture and O2 atmosphere,which distinguished to be an ideal candidate for PV devices.Currently,the synthesis method of Sb2S3 can be categorized as chemical deposition(chemical bath deposition,precursor solution deposition,and hydrothermal deposition,etc.)and physical deposition(thermal evaporation and atomic layer deposition,etc.).The former is convenient,low-cost,and more compatible to industrial production.Moreover,chemical deposition shows a great capacity of coupling optimization means such as doping to control the film growth process.If chemical deposition can be implemented in mass production process,it can effectively diminish the fabrication cost of PV devices,leading a big step towards grid parity.Unsatisfactorily,most of the current chemical deposition methods employ organic solvents as reaction mediums or carriers.Those organic molecules have great chances to remain in the film as recombination centers or trap centers that strongly limit the power conversion efficiency of PV devices.In fixing this problem,this paper developed a new precursor solution system,using 3-mercaptopropionic acid(MPA)and ammonium hydroxide(AH)as solvents.Almost none residual solvents were detected after the fabricated Sb2S3 film was treated properly.Based on this solution system,we assembled PV devices with planner heterojunction structures and gained a champion PCE of 5.57%.Furthermore,given the development trend of PV technology is lairge-scale in device volume and high-efficient in performance,we did some researches on enlarging current devices,fabricated a monolithic solar cell and acquired a Voc of 2.42 V,built a foundation as well as gained experience in this aspect.Chapter 1 involves basic physical knowledge,including the mechanism of photoelectronic eflfect and the band gap theory;gave a very brief review of the history of PV devices,then discussed important parameters of PV devices;the research theme and methodology were delivered at the last section;Chapter 2 introduced functional layers of PV devices,including the material selection and fabrication methods;introduced the measurements of thin films and PV devices.The first two chapters consist the theoretical background of this thesis.Chapter 3 is about synthesis Sb2S3 with precursor solution method.In this Chapter,we unveiled the reaction mechanism of this new solution system,analyzed the phasing process;XPS was used to characterize the compensation information of the Sb2S3 film,according to which,the excess solvents can be totally removed as annealed in a proper temperature;Solar device was assembled in a structure of planner heterojunction,and gained a PCE of 5.57%.In Chapter 4,we gave an introduction of fabricate large scale Sb2S3 devices,laser etching was studied in order to achieve monolithic structure;optimized experimental conditions were presented;finally,the fabricated large-scale cells reached a high Voc of 2.42V.In Chapter 5,we briefly summarized our work;putted up some problems remain to be solved,and moreover,we provided outlooks to those projects.