Vol 2 No 2 (2020) e-ISSN: 2682-8383 Journal of Engineering Technology and Applied Physics (2020) 2, 2, 6: 36-41 https://doi.org/10.33093/jetap © The Authors. This article is licensed under Creative Common License. Published by MMU PRESS. URL: https://journals.mmupress.com/index.php/jetap/index Investigation of MEH-PPV OLED Assisted by An IoT Environment Monitoring System Ibrahim Attia, Guang Liang Ong, Teng Sian Ong, Chen Hon Nee and Seong Shan Yap * Faculty of Engineering, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor, Malaysia. *seongshan@gmail.com https://doi.org/10.33093/jetap.2020.2.2.6 Abstract - Single layer organic light emitting diode (OLED) devices based on poly{[2-methoxy-5-(- 2ethylhexyloxy)-1,4-phenylene]vinylene} (MEH-PPV) are fabricated and studied in this work. There are several factors that affect the performance of the fabricated OLED samples. Some of these factors are related to the fabrication parameters chosen for the OLED fabrication process. The effect of concentration and annealing temperature are investigated. Other environmental factors such as humidity or temperature affect the performance of fabricated OLED samples under long term exposure. An internet of things environment monitoring system (IoT-EMS) is developed to monitor and study the effect of these factors on the performance of the OLED samples. Exposure to humidity is found to severely degrade the samples. In summary, the optimum concentration for MEH-PPV is concluded to be 4 mg/ml, and the best annealing temperature is 90C in this study. It is also deduced that humidity of 72-75 % caused degradation of the samples in less than 20 hours. Keywords— Organic light emitting diodes (OLED), Electroluminescence (EL), Indium Tin Oxide (ITO), IoT environment monitoring system (IoT-EMS), degradation, poly(2-Methoxy-5-(20-Ethyl-Hexoxy)-P- PhenyleneVinylene) (MEH-PPV). I. INTRODUCTION Electroluminescence phenomenon was discovered in 1907. The discovery changed the history of display and opened up endless possibilities for newer display technologies. OLED was discovered later, and showed that it possesses attractive manufacturing advantages such as having a lower cost and higher flexibility as compared to inorganic devices [1]. Electroluminescence behavior from a polymer was first reported in 1990 [2] and since then it was discovered in a wide range of polymers [3]. One of the polymers that allowed low voltage operation is PPV based polymers such as MEH-PPV [4,5]. The efficiency of the fabricated OLED sample can be optimized by controlling the parameters in the fabrication processes of said sample. In the fabrication process, increasing the concentration of the emissive layer will increase the thickness of the sample. Changing the annealing temperature will also cause changes to the OLED’s efficiency. The annealing temperatures chosen are usually higher than the glass transition temperature (Tg) of MEH-PPV which is around 65°C [6] because the electrical characteristics of the sample depends on the polymer chains. When heated above Tg, the polymer chains could move freely and hence enhance the packing of the polymer film. That will improve the electrical efficiency of the polymer. As the annealing temperature increases, the hole injection efficiency also increases, hence, increasing the electrical efficiency (characteristics) of the OLED sample [7,8]. There are external factors that affect the OLED’s efficiency negatively [9]. These external factors cause the OLED sample to degrade and lose its efficiency rapidly until the sample fails. There are two types of degradation, recoverable and unrecoverable [10]. Recoverable degradation occurs a few minutes after a bias have been applied to the sample; however, a change in the physical appearance of the sample will be noticed. Example of recoverable degradation is ionic impurities. The ionic impurities cause the formation of internal electric field, which is opposite to the external applied electric field. After the first forward bias, the internal electric field is formed and it reduces the current density in the sample. However, if a reverse bias is applied to the sample for 10 s, the internal electrical field can be removed and the current density of the sample will be improved [10]. Compare to Journal of Engineering Technology and Applied Physics