Linker-assisted Assembly Of Quantum Dots And Their Application In Solar Cells

Since 1998,Nozik sensitized TiO2 photoelectrodes with InP quantum dots,in the past,quantum dot sensitized solar cells(QDSSCs)have attracted great interest due to their excellent optical stability,quantum size effect,multi-exciton effect,wide variety and low cost.The photoelectric conversion efficiency(PCE)of QDSSCs can reach up to 44%in theory,but the maximum PCE of QDSSCs is only 21.5%,which is still far from the theoretical value.Many factors will limit the photoelectric performance of QDSSCs,such as narrow quantum dot light absorption range,too many defective particle surface,mismatched energy level alignment,too small optical anode,low mobility of charge carriers and so on.In recent years,linkers have been widely used in high-efficiency QDSSCs,but the effect between the mechanism of linkers and quantum dots is often ignored.In this paper,the following studies were carried out on the influence of linker on PCE in QDSSCs:(1)First,CdS QDs with mature technology was used to assist the assembly of metal sulfur group compounds(MCCs)onto the TiO2 photoanode as a connector,and the ZnS was used for post-processing.Then it was assembled with PdSe as counter electrodes to form a cell and the influence of the number of Sn2S64-ligand assisted assembly cycles on the battery performance was texted.As a result,the optimal cycle number is 3,and the corresponding cell efficiency is 1.58%.(2)We have synthesized an environmentally friendly CuInS2(CIS)QDs with wide absorption,which avoids the toxicity of cadmium and chalcogen sulfide QDs.We connect the QDSSCs through metal chalcogenide complexes(MCCs).The results show that the exchange process not only eliminates the insulating organic barrier of charge transfer,but also maintains the quantum constraint band structure.The treatment was verified by energy dispersive X-ray spectrum(EDX),time-resolved photoluminescence and electrochemical impedance spectroscopy.The MCC-capped photoanode exhibits higher photovoltaic performance than the conventional MPA-CIS QDSSCs.And it was investigated the influence of different exchange cycles on cell efficiency.The findings reported can be extended to different nanocrystals and inorganic surface ligands.