posted on 2017-06-16, 00:00authored byWenran Wang, Guocan Jiang, Juan Yu, Wei Wang, Zhenxiao Pan, Naoki Nakazawa, Qing Shen, Xinhua Zhong
Unambiguously
direct adsorption (DA) of initial oil-soluble quantum
dots (QDs) on TiO2 film electrode is a convenient and simple
approach in the construction of quantum dot sensitized solar cells
(QDSCs). Regrettably, low QD loading amount and poor reproducibility
shadow the advantages of DA route and constrain its practical application.
Herein, the influence of experimental variables in DA process on QD
loading amount as well as on the photovoltaic performance of the resultant
QDSCs was investigated and optimized systematically, including the
choice of solvent, purification of QDs, and sensitization time, as
well as QD concentration. Experimental results demonstrated that it
is essential to choose appropriate solvent as well as control purification
cycles of original QD suspensions so as to realize satisfactory QD
loading amount and ensure the high reproducibility. In addition, DA
mode renders efficient electron injection from QD to TiO2, yet low QD loading amount and adverse QD agglomeration in comparison
with the well-developed capping ligand induced self-assembly (CLIS)
deposition approach. Mg2+ treatment on TiO2 photoanodes
can promote the QD loading amount in DA mode. The optimized QDSCs
based on DA mode exhibited efficiencies of 6.90% and 9.02% for CdSe
and Zn–Cu–In–Se QDSCs, respectively, which were
comparable to the best results based on CLIS mode (6.88% and 9.56%,
respectively).