Hybrid Layers of Donor-Acceptor Copolymers with Homogenous Silver Nanoparticle Coverage for Photonic Applications

Abstract

Hybrid layers of donor-acceptor (D-A) copolymers containing N,N′-dialkylperylene-3,4,9,10-tetracarboxydiimide electron-acceptor units covered with silver nanoparticles (Ag-NPs) were prepared by electrochemical doping of pristine layers during reduction processes. In situ optical absorption spectra of the layers were recorded during the formation of Ag-NP coverage. The hybrid layers were characterized by absorption spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). In the absorption spectra of the hybrid layers, a surface plasmon band characteristic of Ag-NPs appeared. Significant improvements in light absorption due to the plasmonic effects of Ag NPs were observed. Stable Ag-NPs with an average diameter of 41–63 nm were formed on the surface, as proven by SEM and XPS. The Ag-NP coverage and size depended on the hybrid layer preparation conditions and on the copolymer composition. The metallic character of the Ag-NPs was proven by XPS. The location in the surface layer was further confirmed by EDX analysis. To the best of our knowledge, this is the first report on such hybrid layers having the potential for a variety of photonic and electronic applications.

Effects of the Donor Unit on the Formation of Hybrid Layers of Donor-Acceptor Copolymers with Silver Nanoparticles

“…The other weaker peaks at higher BEs are associated with shake-up phenomena-π-π* satellite peaks of C=O and aromatic C sp 2 [76][77][78][79]. A decrease in the main peak area and an increase in the satellite/main peak area ratios are observed in the spectra of the hybrid layers, similar to the HR C 1s spectra of CFC8-EHPDI HL layers as analyzed in detail in our previous work [21]. The HR C 1s spectra of the CEHCz-EHPDI layers, which are displayed in Figure 9, were deconvoluted into 5 components corresponding to aromatic C sp 2 , aliphatic C sp 3 , C-N sp 2 , C-N sp 3 , and C=O groups, and π-π* satellite components, which typically appear in the XPS spectra of aromatic compounds.…”

“…The HR Ag 3d spectra were deconvoluted into two Ag 3d 5/2 and Ag 3d 3/2 main components and additional symmetrical lines corresponding to the satellites analogously to the metallic Ag spectrum. The HR Ag 3d spectra of CEHCz-EHPDI hybrid layer surfaces exhibited similar features as the HR Ag 3d spectra of CFC8-EHPDI hybrid layer surfaces, which are analyzed in detail in our previous work [ 21 ]. The satellites S1 and S3, which are separated by ca.…”

“…As the position of the LSPR absorption band maximum depends on the size and shape of the Ag-NPs [ 59 ], this indicates that the Ag-NP properties and coverage in HL1 and HL2 layers differ. The absorption spectra of the HL1 and HL2 layers of the CFC8-EHPDI copolymer with the 9,9-dioctylfluorene D unit also differed, but in another way, as described in detail in our previous paper [ 21 ]. The absorption and difference spectra of both copolymer hybrid layers are displayed in Figure 3 for comparison.…”

“…Recently, we have prepared and characterized hybrid layers of two donor-acceptor (D-A) copolymers (CFC8-DDPDI and CFC8-EHPDI) with homogenous coverage of silver nanoparticles (Ag-NPs) with average sizes below 100 nm [ 21 ]. The CFC8-DDPDI and CFC8-EHPDI copolymers, which were used, consist of 9,9-dioctylfluorene electron-donor (D) units and N , N ′-dialkylperylene-3,4,9,10-tetracarboxydiimide electron-acceptor (A) units, and they differed by the side chains attached to the perylene-3,4,9,10-tetracarboxydiimide (PDI) units (dodecyls and 2-ethylhexyls, respectively).…”

Donor-Acceptor Copolymers with 9-(2-Ethylhexyl)carbazole or Dibenzothiophene-5,5-dioxide Donor Units and 5,6-Difluorobenzo[c][1,2,5]thiadiazole Acceptor Units for Photonics

“…Non-fullerene small-molecule organic electron acceptors such as ITIC-4F or Y6 (Figure 12) can be used. D-A copolymers with perylene-3,4,9,10-tetracarboxydiimide-based A units and various D units (Figure 12) synthesized and studied in our previous work are suitable as electron acceptors due to their higher electron affinities (3.8-3.9 eV) and other desirable properties [46,47,101]. These n-type polymers could also be used in ternary solar cells together with a second acceptor, such as ITIC-4F or Y6, with higher electron affinities and absorption in the NIR region, improving sunlight harvesting.…”