Controllable Prepartion Of Quantum Dot Sensitized Nanocrystalline Films And Its Applications In Solar Cells

Quantum dot sensitized solar cells(QDSSCs)have attracted considerable attention due to its simple fabrication process,low production cost and high theroretic efficiency.Quantum dot sensitized photoanode,taking the role in light absorption and electron transportation,is key important in determing the performance of QDSSCs.In this thesis,we introduced a new route to post-treat the PbS sensitized photoanodes by using I-/I2 solution.The effects of such a treatment on the photovoltaic performances of PbS QDSSCs have been investigated.The specific research results are as follows:1?PbS sensitized photoanodes were fabricated through a SILAR method and post-treatment were performed using I-/I2 solution.Based on XPS analyses,a mechanism of the benefit role of I-/I2 solution treatment in suppressing the defective sites have been proposed.IMPS/IMVS and EIS analyses illustrated that the treatment led to the decrease of defect related charge recombination,the increase of electron injection from PbS QDs to TiO2 and electron collection efficiency.As a result,both the short-circuit photocurrent and open-circuit photovoltage are enhanced,which leads to a high photovoltaic conversion efficiency of 4.82%for PbS QDSSC.2.Mono-dispersed PbS QD was successfully synthesized through a hot-injection method.PbS sensitized photoanodes were fabricated by tethering the pre-synthesied PbS quantum dots on Ti02.The photoanodes were passivated through the deposition of CdS/ZnS and further subjected to I-/I2 solution post-treatment.Light absorption investigations showed that the I-/I2 solution post-treatment reduced the particle size of PbS QD and raised its conduction band,which is benefit to increase the electron injection from PbS QD to Ti02 conduction band.IMVS/EIS analyses showed that CdS/ZnS double treatment is more efficient than ZnS alone treatment in suppressing carrier recombination.In combination of I-I2 solution post-treatment and CdS/ZnS double treatment,the pre-synthesized PbS QDSSCs achieved a short current density of 20.76 mA·cm-2 and a power conversion efficiency of 3.63%.