Real-Time Spectral Evolution of Interchain Coupling and Assembling during Solvent Vapor Annealing of Dispersed Conjugated Polymers
Journal
Macromolecular Chemistry and Physics
Journal Volume
222
Journal Issue
16
Date Issued
2021
Author(s)
Abstract
Solvent vapor annealing (SVA) for polymer treatment is widely used for manufacturing organic photovoltaic devices, but the process is poorly understood on the microscopic scale. In this study, an optical monitoring system is designed and used to perform real-time fluorescence analysis of dispersed poly(3-hexylthiophene) (P3HT) and para-phenylene ethynylene (PPE) films during SVA. The initial swelling of aggregates occurs within seconds. Chain rearrangements then occur and an equilibrium state is reached within minutes. Surface morphologies for both P3HT and PPE polymers are examined using atomic force microscopy (AFM) before and after the SVA process. Although similar transformations from random globules to micrometer-scale nanowires are observed for both polymers, P3HT forms nanowires more easily and quickly than PPE does. The higher solubility of P3HT in chloroform results in superior long-range order; by contrast, PPE chains align into nanowires only with sufficient free space. Real-time spectroscopic monitoring of structures and morphological characterization of such structures through AFM during SVA can improve the understanding of how polymer chains rearrange into ordered structures. ? 2021 Wiley-VCH GmbH
Subjects
conjugated polymers
nanowires
poly(3-hexylthiophene)
poly(para-phenylene ethynylene)
solvent vapor annealing
Atomic force microscopy
Chlorine compounds
Fluorescence
Nanowires
Organic solar cells
Fluorescence analysis
Interchain coupling
Morphological characterization
Optical monitoring systems
Organic photovoltaic devices
Poly-3-hexylthiophene
Solvent-vapor annealing
Spectroscopic monitoring
Conjugated polymers
SDGs
Type
journal article