Study of Tunable Dielectric Permittivity of PBDB-T-2CL Polymer in Ternary Organic Blend Thin Films Using Spectroscopic Ellipsometry

Abstract

The ellipsometric analyses reported in this paper present a novelty by bringing an in-depth optical investigation of some ternary organic blends. This study focuses on the tunability and control of the relative permittivity of active layers by varying the weight ratio of blended materials spin-coated as thin films. To investigate this, an extensive approach based on spectroscopic ellipsometry was conducted on ternary blend (D:A1:A2) thin films, involving a donor [D = chlorinated conjugated polymer (PBDB-T-2Cl)] and two acceptor materials [A1 = a non-fullerene (ITIC-F) and A2 = a fullerene (PCBM)]. The refractive index constitutes a key parameter that exposes insights into the feasibility of photovoltaic cells by predicting the trajectory of light as it transits the device. In this term, higher obtained refractive indexes support higher absorption coefficients. Notably, the dielectric constant can be rigorously tuned and finely calibrated by modest variations in the quantity of the third element, resulting in considerable modifications. Moreover, the inclusion of fullerene in blends, as the third element, results in a smooth topographical profile, further refining the surface of the film. From an electrical point of view, the ternary blends outperform the polymer thin films. The synergistic interaction of constituents emphasizes their potential to enhance solar conversion devices.

Impact of PCBM as a Third Component on Optical and Electrical Properties in Ternary Organic Blends

“…Small adjustments in the quantity of the third element can result in significant changes to the dielectric constant. The dielectric environment changes as acceptor elements are introduced into the polymeric matrix, enhancing its character, as previously reported in [32]. Considering solely ternary blends, the absorption coefficient decreases as the amount of NFA in the blends diminishes.…”

Microstructure and Dielectric Properties of Gradient Composite BaxSr1−xTiO3 Multilayer Ceramic Capacitors

“…Moreover, organic material-based tunable dielectrics exhibit characteristics such as flexibility, light weight, and ease of processing. However, the limited dielectric constant of organic materials, their lower operating frequencies, and the sensitivity of polymer materials to environmental factors make them less suitable for microwave applications [6].…”