Tuning the Optical Properties of MEH–PPV/PFO Hybrid Thin Films via the Incorporation of CsPbBr₃ Quantum Dots

• Main Authors: Saif M. H. Qaid, Bandar Ali Al-Asbahi, Hamid M. Ghaithan, Abdullah S. Aldwayyan
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Coatings
• Subjects: CsPbBr₃ perovskite quantum dots; MEH–PPV/PFO conjugated polymers; composite; light-emitting materials; tunable bandgap
• Online Access: https://www.mdpi.com/2079-6412/11/2/154

The current work examines the effects of cesium lead bromide (CsPbBr₃) perovskite quantum dots (PQDs) on the structural and optical properties of conjugated polymer blends of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH–PPV) and poly(9,9-di-<i>n</i>-octylfluorenyl-2,7-diyl) (PFO). MEH–PPV/PFO composite thin‑films containing PQDs with weight ratios between 0.5 wt.% and 10 wt.% were prepared via a solution-blending method prior to spin-coating on glass substrates. The MEH–PPV/PFO composites’ crystallinity was improved, and the roughness was dramatically increased with higher PQDs content, as confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Conversely, a higher PQDs content resulted in a gradual reduction of the Urbach tail and an increase in the steepness parameter, thereby reducing the localized density of the electronic states within the forbidden bandgap of the hybrids. Moreover, a slight reduction in the direct and indirect bandgaps was found in PQDs/(MEH–PPV/PFO) composite films containing a higher PQDs content and provided evidence of the low concentration of the localized states. The incorporation of the PQDs resulted in enhanced non-radiative energy transfer processes in the MEH–PPV/PFO hybrids, which are very important for the development of optimized optoelectronic devices.