Influence of Solvent Additive 1, 8‐Octanedithiol on P3HT:PCBM Solar Cells. (12th March 2018)

• Record Type: Journal Article
• Authors: Wang, Weijia; Song, Lin; Magerl, David; Moseguí González, Daniel; Körstgens, Volker; Philipp, Martine; Moulin, Jean‐François; Müller‐Buschbaum, Peter
• Is Part Of: Advanced functional materials. Volume 28:Number 20(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-12
• Subjects: crystallinity -- morphology -- organic photovoltaics -- solvent additives -- TOF‐GISANS; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201800209
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Processing solvent additives in polymer:fullerene bulk heterojunction systems are known as a promising method to enhance photovoltaic performance. It is generally agreed that solvent additives enable polymers to have a high degree of molecular order which increases the device performance. However, the understanding of the efficiency enhancement is not complete. There is a lack of insight regarding the quantitative determination of the molecular miscibility between polymer and fullerene as well as the inner morphology changes induced by the additives. In this work, understanding of the influence of the solvent additive 1, 8‐octanedithiol (ODT) is provided on the classic system poly(3‐hexylthiophene‐2, 5‐diyl):[6, 6]‐phenyl‐C61 butyric acid methyl ester (P3HT:PCBM) films. The impact on polymer crystallinity, surface structure, inner morphology, and quantitative molecular miscibility of P3HT and PCBM is studied as a function of ODT volume concentration. The crystallinity is probed with absorption spectroscopy and grazing incidence wide‐angle X‐ray scattering. The morphology and miscibility are characterized via atomic force microscopy and time‐of‐flight grazing incidence small angle neutron scattering. Besides an increased crystallinity and prominent phase separation, ODT increases the solubility of PCBM in P3HT and reduces the size of amorphous P3HT domains. Moreover, solvent processing with a high ODT concentration alters the vertical material composition of the active layer. Abstract : The function of 1, 8‐octanedithiol (ODT) on polymer:fullerene bulk heterojunction systems is comprehensively studied for the well‐established model system poly(3‐hexylthiophene‐2, 5‐diyl):[6, 6]‐phenyl‐C61 butyric acid methyl ester. Besides the positive influence of ODT on crystallinity and surface morphology, the influence on the molecular miscibility between polymer and fullerene is probed, providing a complete correlation between morphology and solar cell efficiency.