The Experimental Investigation of The performance of Phosphor Coating

Abstract

Different screen printing parameters have a distinct effect on the quality of coating that is created. This experimental work looked to measure these parameters. It is divided into two parts where the first part measured the surface wettability of various substrates Wettability measurement was performed through measuring the contact angle between the droplet and the substrate surface. Varying the UV exposure time by putting substrate in the UV ozone cleaner has a considerable effect on the wettability of the surface. Water was supplied to a PEDOT: PSS substrate via Fibro DAT 1100 which is attached to a camera and a computer for capturing and analyzing coatings for the spread of a water droplet on the substrate surface. From these analyses, the main aim is to measure the contact angle between the droplet and the substrate surface which indicates the surface wettability. Some factors may affect the wettability of the surface such as varying the UV time and varying the hold time. As a result, increasing these times will decrease the contact angle where a small contact angle indicates a favorable wettability. The second part measured the electrical resistance and transparency of the printed ink after various printing experiments such as implementing UV treatment, changing the ink and changing the mesh ruling. The Rheometer device was used to test the properties of the specimen. Where this device can be used to measure the properties of the specimen such as the shear modules, in this paper the plate was used to effect on the specimens, where different readings are recorded for these specimens. Also, 24 samples were prepared and the electrical resistance for these samples was measured in this paper. As a result, the electrical resistance for treated samples was greater than that for untreated samples; the electrical resistance of Elentan ink was greater than that for PEDOT at the same conditions. Changing the screen size from (61-64) to (40-100) increase the value of resistance at the same conditions. For the transparency measurements the Elentan ink had a higher transparency than PEDOT ink. The paper also carried out an analysis for the relation between the thickness of the phosphor layer and the lamp output, where the relation was inversely proportion.