Étude de performance et de vieillissement d'un dispositif OLED

Abstract

This thesis presents a method to evaluate the lifetime of a PMOLED display by ADT. It uses photodegradation as accelerant factor. The light was emitted by LEDs with an emission peak at 405 nm, which is in the visible spectrum. The display requires no modification in order to perform the test. The test bench can be built with a minimum of components. The LEDs were controlled with a Darlington transistor driven by an operational-amplifier. To avoid any external light exposure, the test bench was placed in a black box. The whole test bench is ventilated to keep it near room temperature. The selected PMOLED units were UG-9664HDDAG01 and LEDs for photodegradation were LZ1-10UA00-00U8. Those LEDs were powered at an irradiance from 140 W/m2 to 1090 W/m2. After tests, the active parts of displays were more degraded than those turned off. Also, the degraded pixels became thinner at their center. The measurements were taken at every 24 hours with a calibrated powermeter sets at the main peak wavelength of the PMOLED display. It is known that the blue light emitter has the shortest lifetime. This work focuses on the degradation of the blue emitter. The tests finishes when the displays reach half of the original irradiance. The data were presented in a log-log plot and the relation seems linear for the obtain results. If the tested displays were used under the same conditions as a solar panel, as described in the standard ASTM G173-03 at 405 nm, the displays would last 21,866 hours. The same data was analysed with Weibull and lognormal distributions in order to get average life. According to those distributions, the average life time would respectivetly be 23 666 hours and 21 995 hours. The manufacturer specified a lifetime of 10 000 hours estimated by thermal cycling. If that lifetime is considered as a reference, the display should be exposed to an irradiance of 2.31 W/m2 at 405nm in order to respect that reference.

Date	15 May 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Sylvain G. Cloutier (Supervisor)