Stoichiometric dependence of TiOx as a cathode modifier on band alignment of polymer solar cells
Journal
Solar Energy Materials and Solar Cells
Journal Volume
125
Pages
233-238
Date Issued
2014
Author(s)
Abstract
In this study, we systematically investigated the stoichiometric dependence of titanium oxide (TiOx, x=1.56-1.93) as a cathode modifier on the device performance of polymer solar cells. Electronic structures of the synthesized TiOx modifier layers were controlled by tuning the compositions of various O/Ti ratios. The effective cathode work-functions and the corresponding device performances of polymer solar cells are systematically changed as a result of inserting the TiOx modification layers. Interfacial modification of the Al cathode with a low O/Ti ratio of TiO x layer yields the best performing photovoltaic device as a result of a largest built-in potential. The correlation of power conversion efficiencies and carrier dynamics of these devices by inserting various TiOx modification layer is further examined by using the Mott-Schottky analysis and the impedance spectroscopy technique. The consistent result shows an enhanced carrier collection efficiency and a reduced charge recombination rate of the device via adequate band alignment between the photoactive layer and the cathode using the TiOx modification layer with an optimized O/Ti ratio. © 2014 Elsevier B.V.
Subjects
Built-in potential; Cathode work-function; Charge recombination; Polymer solar cell; Solution processable
SDGs
Other Subjects
Alignment; Electronic structure; Polymers; Solar cells; Titanium oxides; Built-in potential; Charge recombinations; Polymer Solar Cells; Solution processable; TiO; Cathodes
Publisher
Elsevier
Type
journal article