| dc.description.abstract | Dye-sensitized solar cells (DSSCs), one of the third generation solar cells, are getting more popular these days, due to their light weight, low cost and easy to make. In DSSCs, electrolyte plays the role of re- generating the oxidized dye, transferring hole to the counter electrode and determining the theoretical Voc of the devices. The most common electrolyte used in DSSCs is iodide/triiodide (I-/I3-) redox couple. However, I-/I3- redox system has some disadvantages, such as the fixed redox potential and the structure of the electrolyte can not be modified, which limits it development. Many scientists are now looking for new electrolytes to increase the efficiency of DSSCs. Cobalt based electrolyte, due to it adjustable potential which can be used to increase the Voc of DSSCs, is one of the potential electrolytes. However, cobalt based electrolyte has the disadvantage of easily capture the electron on TiO2 electrode, increasing the dark current, therefore reducing Voc of the device. We use the SJW-B18 and CYC-B11H with long alkyl chain on their ancillary ligand developed by our lab to avoid the charge re- combination. In the study, we found that compared to CYC-B11H dye using SJW-B18 dye, which has 4 terminal alkyl chain, as a sesitizer can protect the surface of TiO2 electrode, increase the resistance between dye adsorbed on TiO2 electrode and electrolyte, prevent the dark current, increase the life time of the electron on TiO2 electrode and decrease the loss of Voc. The highest efficiency of the device based on SJW-B18 dye combined with cobalt electrolyte is 7.08%. The optimal composition of the electrolyte is 0.2 M Co(II), 0.02 M Co(III), 0.5 M TBP and 0.1 M LiClO4 in acetonitrile. | en_US |