GaAs/P3HT bilayer hybrid structure.

• Main Author: Nguyen, Hung Quang.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Physics::Optics and light
• Online Access: http://hdl.handle.net/10356/55141
• Institution: Nanyang Technological University

Conjugated polymers such as P3HT attract great attention of photovoltaic researchers due to its advantages compared to solid film materials. A hybrid organic-inorganics system, with P3HT as active layer blended with group III-V semiconductor GaAs, is fabricated to study charge separation at the interface and polarons formation due to photo-doping. In order to achieve these goals, bilayer organic/inorganic photovoltaic devices were fabricated with different architectures of electrodes; and were measured by different methods including I-V characterization measurement, steady state photocurrent measurement and photo-induced absorption measurement (PIA). I-V characterization measurement is an electrical method showing the dependence of photocurrent on bias voltage; and through analyzing I-V curves of each device, fill factors and efficiencies of the devices can be compared to show the effect of electrode on device’s performance. Steady state photocurrent measurement investigates the dependence of photocurrent on wavelengths/energies of the incident photons from that how the device responses to a specific wavelength can be recorded. Photocurrent measurement shows the effect of bias voltage on charge separation in the device, when negative bias leads to higher photocurrent. Lastly, PIA spectroscopy is used to investigate the photogeneration of charge carriers in the organic/inorganic interface of the device. PIA spectroscopy is a pump-probe measurement, which can obtain the change in reflectance/transmittance of the device depends on the range of probe signal. The measurement shows a broad photoinduced absorption signal at around 1.24eV, which indicates the formation of polaron P2 of P3HT on GaAs/P3HT hybrid system.