Study Of Low-Temperature Preparation And Performance Of The PbS Colloidal Quantum Dot Solar Cells

Colloidal quantum dots(CQDs) are solution-synthesized and-processed semiconductor nanocrystals that provide a tunable bandgap via quantum size effect. The promise in multiple exciton generation makes CQDs very attractive to low-cost, high-efficiency solar cells. Here we synthesized well-crystallized and nearly monodispersed tetragonal PbS CQDs, Cd3P2 CQDs and Sb2S3 nanocrystals. By solution and surface passivation strategy, we prepared the controllable electrical conductivity, adjustable carrier concentration and high mobility film, and then made the quantum junction solar cells.Firstly the article introducted the synthesis of PbS CQDs, Cd3P2 CQDs and Sb2S3 nanocrystals, the size of nanocrystals can be controlled by changing the temperature, the ratio of precursor and the reaction time. The XRD and TEM characterization show that the nanocrystals are nearly monodispersed which is greatly prepared for device fabrication. And then we fabricated the Cd3P2/PbS quantum junction solar cell device by solution-process at low temperature, and demonstrated the influence of CQD size and Ag-doping on the performance of devices. We find that the CQDs size has a great impact on the open-circuit voltage(Voc); the AgCl doping can improve the short circuit current(Jsc) and AgNO3 doping can improve the Voc. And finally we optimized the device structure of PbS CQDs solar cells, tried the p-PbS/n-PbS homojunction devices and low-toxicity Sb2S3/PbS solar cell. We demonstrated the influence of film thickness and ligand exchanged time on the performance of p-PbS/n-PbS devices. We find that the film thickness may influence the depletion region and absorption, therefore affect the Voc and Jsc; the ligand treated can improve the density of carrier as well as the defect of film. In view of the poor quality of Sb2S3 film, we fabricated the Zn O nanocrystals film on ITO first and got a certain efficiency of devices.