Macroscale and Nanoscale Morphology Evolution during in Situ Spray Coating of Titania Films for Perovskite Solar Cells

Abstract

Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol-gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not only on micellization but also on solvent evaporation during the spray coating. Perovskite (CHNHPbI) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

Humidity‐Induced Nanoscale Restructuring in PEDOT:PSS and Cellulose Nanofibrils Reinforced Biobased Organic Electronics

“…Spray deposition is a non‐equilibrium deposition process under applied heat where droplets evaporate on the position they are deposited. [ 38 ] The humidified nanocomposite film is swells only very little compared to previously reported experiments on pure PEDOT:PSS electrodes. [ 5 ] Obviously, the film swelling is limited by the mechanical integrity enhancement due to the CNF reinforcing agent.…”

Core–Shell Nanoparticle Interface and Wetting Properties

“…Most particles will be found on the edge of the former droplet, and a coffee ring appears. This phenomenon has been previously extensively studied and is well known in spray‐deposited thin films 62. This desired and targeted low number of NPs per area unit means that the analysis is indeed for sub‐monolayers and the resulting effect on surface wetting will be more affected by the chemical nature of the NP and not secondary roughness as for multilayers 19…”

Morphology Phase Diagram of Slot‐Die Printed TiO2Films Based on Sol–Gel Synthesis

“…The combination of sol–gel chemistry with an amphiphilic block copolymer acting as a structure‐directing template was proven to be a promising route for producing nanostructured TiO 2 films . The obtained sol‐gel solution can be directly deposited by various film fabrication techniques, such as spin coating, solution casting, doctor blading, spray coating, or inkjet printing …”

“…[14,15] The combination of sol-gel chemistry with an amphiphilic block copolymer acting as a structure-directing template was proven to be a promising route for producing nanostructured TiO 2 films. [16][17][18][19][20] The obtained sol-gel solution can be directly deposited by various film fabrication techniques, such as spin coating, [21] solution casting, [22] doctor blading, [23] spray coating, [24] or inkjet printing. [25] To date, most attention of such kind of wet chemical TiO 2 film fabrication has only been paid to laboratory-scale Mesoporous titania films with tailored nanostructures are fabricated via slot-die printing, which is a simple and cost-effective thin-film deposition technique with the possibility of a large-scale manufacturing.…”