Yeh Y.-C.Li S.-S.Wu C.-C.Shao T.-W.Kuo P.-C.Chen C.-W.CHUN-WEI CHEN2019-11-272019-11-27201409270248https://www.scopus.com/inward/record.uri?eid=2-s2.0-84897387476&doi=10.1016%2fj.solmat.2014.03.017&partnerID=40&md5=9b443580474dfb0cf83070217cc08db6https://scholars.lib.ntu.edu.tw/handle/123456789/432814In 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.Built-in potential; Cathode work-function; Charge recombination; Polymer solar cell; Solution processable[SDGs]SDG7Alignment; Electronic structure; Polymers; Solar cells; Titanium oxides; Built-in potential; Charge recombinations; Polymer Solar Cells; Solution processable; TiO; Cathodesjournal article10.1016/j.solmat.2014.03.0172-s2.0-84897387476