Stacking Orientation Mediation of Pentacene and Derivatives for High Open-Circuit Voltage Organic Solar Cells.
In this Letter, we investigated the effect of the molecular stacking orientation on the open circuit voltage (VOC) of pentacene-based organic solar cells. Two functionalized pentacenes, namely, 6,13-diphenyl-pentacene (DP-penta) and 6,13-dibiphenyl-4-yl-pentacene (DB-penta), were utilized. Different molecular stacking orientations of the pentacene derivatives from the pristine pentacene were identified by angle-dependent near-edge X-ray absorption fine structure measurements. It is concluded that pentacene molecules stand up on the substrate surface, while both functionalized pentacenes lie down. A significant increase of the VOC from 0.28 to 0.83 V can be achieved upon the utilization of functionalized pentacene, owing to the modulation of molecular stacking orientation, which induced a vacuum-level shift.
†Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Chi-Ta
CT
Chou
Chien-Hung
CH
Lin
†Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Yian
Y
Tai
†Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Chin-Hsin J
CH
Liu
Li-Chyong
LC
Chen
⊥Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
Kuei-Hsien
KH
Chen
VOC; molecular orientation; organic solar cell; photovoltaic