The Study Of Deposition Strategies And Photovoltaic Device Performance Of Antimony Sulfide Thin Film

Exploring superior photovoltaic materials and improving device performance are of great significance to enhance the developmet of photovoltaic industry.Sb₂S₃ as a low-cost,stable and environmentally friendly binary compound owns suitable bandgap?1.73 eV?and high light absorption coefficient(>10⁵ cm^-1 at visible light region),which showing great potential in photovoltaic application.Furthermore,Sb₂S₃ can be an ideal candidate to match with Si-based tandem structure and promote the progess of next-generation Si solar cells.This project focuses on deposition processes,back-contact treatment,interface epitaxy,defect recombination,alloy research and tandem structure to develop efficient and stable Sb₂S₃ thin film solar cells.Firstly,the compact Sb₂S₃ film with high crystallinity was deposited by rapid thermal evaporation?RTE?method,and the basic physical parameters were measured to provide guidance for device performance optimization.Usually,Sb₂S₃ is applied to dye sensitized solar cell with organic hole transport materials?HTM?,indicationg high cost and poor stability.Thus,we fabricated a full-inorganic planar TiO₂/Sb₂S₃ thin film solar cell free of HTM.In order to increase carrier density and weaken back contact barrier,the selenium atmosphere annealing process was designed to treat the Sb₂S₃ surface.The series resistance?Rs?,quality factor?A?and reverse saturation current density?J₀?of the treated device were significantly reduced,and the Sb₂S₃ doping concentration reached 9.3×10¹⁵ cm^-3.The Se treatment passivates bulk defects as a doping effect and reduces the back contact barrier by alloying the surface.The Sb₂S₃ solar cell obtained a power conversion efficiency?PCE?of3.2%.The Se-annealed Sb₂S₃ device could keep stable for more than 400 hour illumination and six-month storing in air.As the device performance was limited by interface defect recombination,one-dimensional charge transport and high reflection loss.Herein,we developed a quasi-epitaxial growth strategy for PN junction interface and Sb₂S₃ orientation control.By engineering the facet expose and oxygen vacancy of TiO₂ substrate,Sb₂S₃ film realized epitaxial growth from TiO₂ layer according to the coincident diffraction pattern by TEM.The Sb₂S₃ film was dominated by[221]orientation and each grain grows independently from the substrate.For the epitaxial solar cell,systematic physical characterizations prove that the interface quality of PN junction is significantly improved,and both the interface and bulk recombination from defects are suppressed.The open circuit voltage(V_OC)was increased from 0.49 V to 0.65 V.In addition,Sb₂S₃ surface was optimized by tuning the grain sizes to form strong light trapping effect.The Sb₂S₃ with 3.2?m revealed most efficient light absorption and the short-circuit current density(J_SC)of solar cell was enhanced about 21%.The final optimal device with high stability obtained a PCE of 5.4%,which was the best efficiency for full-inorganic Sb₂S₃ solar cells.Sb₂(Se_xS_1-x)₃ alloy film with tunable bandgaps can easily obtain from Sb₂S₃ and Sb₂Se₃,which further improve device performance by balancing V_OC and J_SC.The present work developed a close-space dual-source evaporation method to successfully deposit high-throughput Sb₂(Se_xS_1-x)₃ film library and designed solar cell arrays to explore the effect of Se to device performance.On surface of the obtained alloy film,the x value of Se content evolved from 0.09 to 0.84 by a series of complementary characterizations.The bandgaps decreased from 1.66 eV to 1.2 eV.And the other ralated properties also gradually evolved with Se content.At depth direction,the alloy film kept high crystallinity and composition consistency.The selenium-rich alloy film showed higher carrier lifetime,shallower defect and smaller band offset,which reduces recombination loss.After detailly studying the evolution between device performance and composition,the optimal Sb₂(Se_0.68S_0.32)₃ device achieved a PCE of 5.7%.Finally,the thesis explored the application of Sb₂S₃ as a top-solar-cell material in tandem solar cell.We designed and fabricated the tandem solar cells with Sb₂S₃ and PbS quantum dots.The quantum dots with exciton absorption peak of 945 nm could well match the Sb₂S₃ in spectrum.The optimal thickness of Sb₂S₃ film as top cell was 350 nm.In tandem solar cell,1 nm-Au and 200 nm ZnO nanoparticle as the middle layer could effectively reduce the barrier and improve V_OC and fill factor.The tandem solar cell achieved 4.7%PCE with aV_OC of 1.11 V,which was the superposition of Sb₂S₃ and PbS quantum dot solar cells.The exploration of Sb₂S₃/PbS tandem structure would provide a reference for further application in Si tandem solar cell.