Inspection of substrate-heated modified PEDOT:PSS morphology for all spray deposited organic photovoltaics

2015

J Coat Technol Res

In an attempt to improve surface wetting and coating characteristics, a novel technique, i.e., imposing ultrasonic vibration on the substrate, is introduced. This technique is combined with conventional ultrasonic spray coating, thus substrate vibration-assisted spray coating (SVASC), and is employed to fabricate PEDOT:PSS thin films. PEDOT:PSS is a co-polymer, commonly used as solar cell buffer layers and thin-film electrodes. Advanced surface characterization techniques, such as atomic force microscopy and confocal laser scanning microscopy are utilized. The results show that the application of the imposed vibration on the substrate results in a significant decrease in surface roughness, film thickness, and the number of defects and pin-holes. In terms of the film functionality, the electrical conductivity of the PED-OT:PSS films made using the SVASC technique shows a four-time increase, compared to those made by conventional ultrasonic spray coating. In conventional ultrasonic spray coating, increasing the number of spray passes or deposition layers usually improves the coating uniformity. For aqueous PEDOT:PSS solution and within the range of the values of the parameters investigated in this work, with imposed substrate vibration, the number of spray passes is immaterial, as far as the film uniformity is concerned. However, the application of multiple spray passes enhances the film's electrical conductivity. Our unprecedented results on the combined substrate vibration with spray coating provide a platform for low-cost fabrication of solutionprocessed thin-film solar cell devices, and a forward step toward commercialization of emerging solar cells, such as polymer and perovskite solar cells. The positive effect of using imposed substrate vibration on spray-on solar cell thin films may be deployed in other coating (e.g., spin coating) and spray coating applications as well.

Section: Vibrating Substratesupporting

confidence: 71%

Substrate vibration-assisted spray coating (SVASC): significant improvement in nano-structure, uniformity, and conductivity of PEDOT:PSS thin films for organic solar cells

Zabihi

2015

J Coat Technol Res

“…The electron blocking PEDOT:PSS layer, which could also function as the anode in an inverted configuration, has been fabricated by spray coating and studied rather well [8][9][10][11][12][13][14][15][16][17][18]. The objective of those studies has been to improve the performance of the layer by adjusting the processing parameters.…”

Section: Recent Advances On Spray-on Polymer Solar Cellsmentioning

confidence: 99%

“…The setback, however, is that this is not a one step process thus removing the main advantage of spray coating as a fast process with roll-to-roll capability. Spray-on PEDOT:PSS layers may also be modified by adding selected solvents and also by post annealing to improve their conductivity and structure [9].…”

Section: Recent Advances On Spray-on Polymer Solar Cellsmentioning

confidence: 99%

Spray-on Thin Film PV Solar Cells: Advances, Potentials and Challenges

2014

Coatings

137

Abstract:The capability to fabricate photovoltaic (PV) solar cells on a large scale and at a competitive price is a milestone waiting to be achieved. Currently, such a fabrication method is lacking because the effective methods are either difficult to scale up or expensive due to the necessity for fabrication in a vacuum environment. Nevertheless, for a class of thin film solar cells, in which the solar cell materials can be processed in a solution, up scalable and vacuum-free fabrication techniques can be envisioned. In this context, all or some layers of polymer, dye-sensitized, quantum dot, and copper indium gallium selenide thin film solar cells illustrate some examples that may be processed in solution. The solution-processed materials may be transferred to the substrate by atomizing the solution and carrying the spray droplets to the substrate, a process that will form a thin film after evaporation of the solvent. Spray coating is performed at atmospheric pressure using low cost equipment with a roll-to-roll process capability, making it an attractive fabrication technique, provided that fairly uniform layers with high charge carrier separation and transport capability can be made. In this paper, the feasibility, the recent advances and challenges of fabricating spray-on thin film solar cells, the dynamics of spray and droplet impaction on the substrate, the photo-induced electron transfer in spray-on solar cells, the challenges on characterization and simulation, and the commercialization status of spray-on solar cells are discussed.

“…The approximate thickness of the layers is also given [7]. PEDOT:PSS layer, which is an electron blocking layer and also an anode in some configurations, has been fabricated by spray coating and studied rather well [8][9][10][11]. In an attempt to reduce or eliminate the defects such as pinholes and non-uniformities, Lee et al [12,13] studied the effect of annealing and also the effect of using various solvents for spray coating of P3HT:PCBM layer on PEDOT:PSS.…”

Section: Introductionmentioning

confidence: 99%

Spray-on PEDOT:PSS and P3HT:PCBM Thin Films for Polymer Solar Cells

Newton

2014

Coatings

Abstract:PEDOT:PSS electron-blocking layer, and PEDOT:PSS + P3HT:PCBM stacked layers are fabricated by ultrasonic atomization and characterized by scanning electron microscopy (SEM) and optical profilometry. The measured thicknesses based on SEM and optical profilometry are quite different, indicating the incapability of measurement techniques for non-uniform thin films. The thickness measurements are compared against theoretical estimations and a qualitative agreement is observed. Results indicate that using a multiple pass fabrication strategy results in a more uniform thin film. It was also found that the film characteristics are a strong function of solution concentration and spraying passes, and a weak function of substrate speed. Film thickness increases with solution concentration but despite the prediction of theory, the increase is not linear, indicating a change in the film porosity and density, which can affect physical and opto-electrical properties. Overall, while spray coating is a viable fabrication process for a wide range of solar cells, film characteristics can be easily altered by a change in process parameters.