Preparation Of All Solid-state Compact PbS Quantum-dot Thin Film Sensitized TiO₂ Nanorod Array Solar Cells And Research Of Photovoltaic Performance

Quantum dot solar cells include schottky quantum dot solar cells,depleted heterojunction solar cells,quantum dot-sensitized solar cells?QDSCs?,and quantum dot-polymer hybrid solar cells.At present,the photoelectric conversion efficiency?PCE?of Zn-Cu-In-Se QDSCs and PbS/CdS QDSCs using polysulfide liquid electrolytes has reached 12.34% and 7.90%,respectively.Due to the leakage of liquid electrolytes,all solid-state PbS QDSCs have attracted the attention of the scientific community.Considering the balance of the hole transporting distance limit and the loading of PbS QDs in solid-state PbS QDSCs,the rutile phase TiO₂ nanorod array with short length,small diameter and high areal density was prepared by hydrothermal method and used as the photo anode.The lead nitrate which was strong electrolyte and easily soluble in water,the lead acetate which was weak electrolyte and easily soluble in water,the lead halide which was strong electrolyte and insoluble in water and lead fatty acid lead with different chain lengths were used as lead sources in the deposition of PbS QDs by spin-SILAR,respectively.The effects of different lead sources,fatty acid chain length and MPA surface modification of TiO₂ nanorod arrays on the crystalline size,morphology and optical absorption of PbS QDs were systematically studied.And the effect of all solid-state PbS QDs with spiro-OMe TAD as solid electrolyte on photovoltaic performance of solar cells.The main research contents are as follows:?1?Rutile TiO₂ nanorod arrays with short length?200 nm?,small diameter?20 nm?and high surface density?720 ?m-2?were prepared by hydrothermal method,and firstly used in all solid-state PbS QDSCs.Using Pb?NO₃?₂ which was strong electrolyte and easily soluble in water as lead source,and Na₂S?9H₂O was used as sulfur source,compact PbS QD thin films were deposited on 200 nm long TiO₂ nanorod arrays by spin-SILAR method with introducing dithioglycol in the deposition process.The effects of the number of spin-coating cycles on the crystallite size and morphology of PbS QDs,as well as the photoelectric conversion properties of all solid-state compact PbS QD thin films senstized solar cells were studied.The highest PCE was 4.12%.?2?Lead acetate which was weak electrolyte and easily soluble in water was used as lead source,and PbS QDs were deposited on 360 nm long TiO₂ nanorod array.the reaction mechanism of PbS QDs deposited by lead acetate as lead source and the reason why acetate ion pair inhibited the crystallite growth of PbS QDs were revealed.When the number of spin-SILAR cycles is 20,compact PbS QD thin films can be formed onthe surface of TiO₂ nanorods,and the PCE of all solid-state compact PbS QD thin films senstized solar cells can reach 3.57%.?3?Compact PbS QD thin films were deposited on a 550 nm long TiO₂ nanorod array using strong electrolyte of lead halide?PbI₂,PbBr₂,PbICl?as lead sources,which improved carrier injection and transport efficiency.The recombination of electrons and holes between PbS QDs/spiro-OMe TAD layers was improved.The effects of lead halide on the crystallite size of PbS QDs and the photovoltaic performance of all solid-state compact PbS QD thin films sensitized solar cells were also studied.The rate relationship between the formation of PbS QDs by the reaction of lead halide with S^2-,and the charge recombination between compact PbS QD thin film and spiro-OMe TAD layer was clarified.?4?Three kinds of fatty acids?n-butyric acid,n-hexanoic acid,n-octanoic acid?and Pb O were used to prepare Pb?C₃H₇COO?₂,Pb(C₅H₁₁COO)₂,Pb(C₇H₁₅COO)₂ precursor solutions.The effect of the ligand chain length of fatty acids on average crystallite size,morphology and optical absorption of PbS QDs,and the photoelectric conversion properties of all solid-state compact PbS QD thin films sensitized solar cells were studied.?5?The rutile TiO₂ nanorod arrays with a length of 550 nm were modified by MPA to solve the serious problem of electron and hole recombination at the interface of PbS QD thin film/spiro-OMe TAD.The effect of MPA surface modification on photoelectric conversion properties of all solid-state PbS QDSCs was studied when Pb?NO₃?₂ and PbAc)₂?3H₂O were used as lead sources,respectively.