Merocyanines for vacuum-deposited small-molecule organic solar cells
Journal
Organic Electronics: physics, materials, applications
Journal Volume
26
Pages
319-326
Date Issued
2015
Author(s)
Abstract
Abstract We report here synthesis and photovoltaic properties of three merocyanines dyes (DPPT, DTPT, 1-NPPT) which are functionalized with electron withdrawing thiazolidenemalononitrile and electron rich diarylamine functionalities. It is found that structural feature of the diarylamino groups has a profound effect on the physical properties such as the absorption spectrum, oxidation potential, and HOMO/LUMO energy levels. The compound DTPT containing a better electron-donating ditolyl group, exhibits red-shifted absorption with relatively higher molar extinction coefficient, indicating its better light-harvesting ability. Hole mobility of these compounds is found to be strongly dependent on the various intermolecular interactions. Interestingly, single crystal structures reveal that the crystal packing motifs are rather closely related to the observed hole mobility in a trend of DPPT > DTPT > 1-NPPT. Vacuum-processed small-molecule organic solar cells were fabricated using the title merocyanines as p-type materials (donor) in combination with fullerene (C60 or C70) as n-type material (acceptor) with various device configurations. Among them, the DPPT-based devices outperform the devices based on DTPT and 1-NPPT. The power conversion efficiency (PCE) of DPPT-based device was improved from 1.55% of a BHJ device to 2.63% of a PMHJ device and 3.52% of a PMHJ device without the thin donor layer. © 2015 Elsevier B.V.
Subjects
Bulk heterojunction; Merocyanine; Organic photovoltaic; Planar-mixed heterojunction; Small molecule organic solar cell
SDGs
Other Subjects
Absorption spectroscopy; Heterojunctions; Hole mobility; Molecules; Single crystals; Solar cells; Solar power generation; Vacuum applications; Bulk heterojunction; Device configurations; Intermolecular interactions; Merocyanine; Molar extinction coefficient; Organic photovoltaics; Power conversion efficiencies; Small-molecule organic solar cells; Organic solar cells
Type
journal article