Effect of illumination intensity on a self-powered UV photodiode based on solution-processed NPD:Alq3 composite system

• Main Authors: Alzahrani, Hanan, Sulaiman, Khaulah, Muhammadsharif, Fahmi F., Abdullah, Shahino Mah, Mahmoud, Alaa Y., Bahabry, Rabab R., Ab Sani, Siti Fairus
• Format: Article
• Published: SPRINGER 2021
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.um.edu.my/28603/
• Institution: Universiti Malaya

In this work, the impact of UV illumination intensity on a self-powered photodiode based on organic NPD:Alq3 composite is comprehensively investigated. Solution-processed spin coating was used to fabricate the active layers followed by electrode deposition to form devices with architecture ITO/PEDOT:PSS/NPD:Alq3/LiF/Al. UV-Vis and PL spectrometers were used to investigate the properties of the active layer, while a Keithley source meter was utilized to record the current-voltage response of the photodiodes. Results showed that the self-powered photocurrent was linearly increased (with logarithmic gradient similar to 0.5, confirming the presence of a bimolecular recombination), while the photovoltage was logarithmically increased with illumination intensity. A sensitivity of 1.3 x 10(5) was achieved with responsivity and detectivity of 5.39 mA/W and 5.25 x 10(11) Jones, respectively at 40 mW/cm(2) illumination. The photodiode sensitivity was found to be linearly increased, while the responsivity and detectivity were exponentially decreased with illumination intensity. The variation of bulk resistance of the photodiode followed an exponential and linear relation under low and high illumination intensities, respectively.