Tuning of the Morphology and Optoelectronic Properties of ZnO/P3HT/P3HT-b-PEO Hybrid Films via Spray Deposition Method

Abstract

The self-assembly of amphiphilic diblock copolymers yields the possibility of using them as a template for tailoring the film morphologies of sol-gel chemistry-derived inorganic electron transport materials, such as mesoporous ZnO and TiO. However, additional steps including etching and backfilling are required for the common bulk heterojunction fabrication process when using insulating diblock copolymers. Here, we use the conducting diblock copolymer poly(3-hexylthiophene)- block-poly(ethylene oxide) (P3HT- b-PEO) in which P3HT acts as charge carrier transport material and light absorber, whereas PEO serves as a template for ZnO synthesis. The initial solution is subsequently spray-coated to obtain the hybrid film. Scanning electron microscopy and grazing-incidence small-angle X-ray scattering measurements reveal a significant change in the morphology of the hybrid films during deposition. Optoelectronic properties illustrate the improved charge separation and charge transfer process. Both the amount of the diblock copolymer and the annealing temperature play an important role in tuning the morphology and the optoelectronic properties. Hybrid films being sprayed from a solution with the ratio of ω, ω, and ω of 2:1:1 and subsequent annealing at 80 °C show the most promising morphology combined with an optimal photoluminescence quenching. Thus, the presented simple, reagent- and energy-saving fabrication method provides a promising approach for a large-scale preparation of bulk heterojunction P3HT/ZnO films on flexible substrates.

Comparison of UV Irradiation and Sintering on Mesoporous Spongelike ZnO Films Prepared from PS-b-P4VP Templated Sol–Gel Synthesis

“…All the ZnO films show high transmittance in the visible region, which makes it possible for the adsorbed dye molecules to absorb more photons. For the direct bandgap of the wurtzite phase, which is also confirmed in our earlier work, , Tauc’s equation is used where α is the absorption coefficient, A is a constant, h υ is the photon energy, E g is the bandgap energy, and n = 1/2 is for direct transition Figures S6c and 6d show the curves by plotting (α h υ) 2 as a function of photon energy and the corresponding linear fits (dashed lines) at the absorption edge.…”

“…All the ZnO films show high transmittance in the visible region, which makes it possible for the adsorbed dye molecules to absorb more photons. For the direct bandgap of the wurtzite phase, which is also confirmed in our earlier work, 26,58 Tauc's equation is used…”

Multidimensional Morphology Control for PS‐b‐P4VP Templated Mesoporous Iron (III) Oxide Thin Films

“…Grazing‐incidence small‐angle X‐ray scattering (GISAXS) ideally complements microscopic imaging techniques as it readily provides statistical structure information at both, the surface and the bulk of the thin film. [ 48 ] Figure a–c shows the 2D GISAXS data of the α‐Fe 2 O 3 thin films prepared with DMF solvent. The shape of the Bragg peaks indicates the presence of well‐ordered nanostructures in the horizontal direction of the thin films.…”

Morphology Tuning of ZnO/P3HT/P3HT-b-PEO Hybrid Films Deposited via Spray or Spin Coating

“…In our previous work, we demonstrated that this diblock copolymer improves the interfaces of ZnO and P3HT greatly as compared to the morphology of the hybrid films without templating. 24 In the present work, different deposition methods, namely, spray and spin coating, are compared with respect to the obtained hybrid film morphologies. Given the industrial relevance of spray coating, different weight ratios of ZnO are investigated for the sprayed samples to further improve the morphology of sprayed hybrid films.…”

“…The P3HT block acts as a charge carrier transport material in conjunction with the P3HT homopolymer, while the PEO block performs its role as a template for growing the ZnO nanoparticles from the precursor. In our previous work, we demonstrated that this diblock copolymer improves the interfaces of ZnO and P3HT greatly as compared to the morphology of the hybrid films without templating . In the present work, different deposition methods, namely, spray and spin coating, are compared with respect to the obtained hybrid film morphologies.…”