Fundamental Study on the Effect of Spray Parameters on Characteristics of P3HT:PCBM Active Layers Made by Spray Coating

Abstract

This paper is an attempt to elucidate the effects of the important spray characteristics on the surface morphology and light absorbance of spray-on P3HT:PCBM thin-films, used as an active layer in polymer solar cells (PSCs). Spray coating or deposition is a viable scalable technique for the large-scale, fast, and low-cost fabrication of solution-processed solar cells, and has been widely used for device fabrication, although the fundamental understanding of the underlying and controlling parameters, such as spray characteristics, droplet dynamics, and surface wettability, is still limited, making the results on device fabrication not reproducible and unreliable. In this paper, following the conventional PSC architecture, a PEDOT:PSS layer is first spin-coated on glass substrates, followed by the deposition of P3HT:PCBM using an automatic ultrasonic spray coating system, with a movable nozzle tip, to mimic an industrial manufacturing process. To gain insight, the effects of the spray carrier air pressure, the number of spray passes, the precursor flow rate, and precursor concentration are studied on the surface topography and light absorbance spectra of the spray-on films. Among the results, it is found that despite the high roughness of spray-on films, the light absorbance of the film is satisfactory. It is also found that the absorbance of spray-on films is a linear function of the number of spray passes or deposition layers, based on which an effective film thickness is defined for rough spray-on films. The effective thickness of a rough spray-on P3HT:PCBM film was found to be one-quarter of that of a flat film predicted by a simple mass balance. OPEN ACCESSCoatings 2015, 5 489

Defect-Free Large-Area (25 cm2) Light Absorbing Perovskite Thin Films Made by Spray Coating

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New design of potentially low-cost solar cells using TiO2/graphite composite as photon absorber

“…They found that the absorption of the active layer increases with active layer thickness. Yu Xie et al investigated the effects of thickness on light absorbance of P3HT:PCBM thin-films which is used as an active layer in polymer solar cells (PSCs) [26]. This active material was deposited using spray method.…”

A Review of Conductive Metal Nanomaterials as Conductive, Transparent, and Flexible Coatings, Thin Films, and Conductive Fillers: Different Deposition Methods and Applications

“…After deposition, washing the thin film with water or acid treatment is recommended to remove the residual solvents. Reports on spray deposition of Ag NWs [21,22,33,60,61] have demonstrated the workability of this method [62,63].…”