Metal assisted chemically etched silicon nanowires for application in a hybrid solar cell
Loading...
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Western Cape
Abstract
Photovoltaic (PV) devices based on inorganic-organic hybrid active layers have been
extensively studied for over a decade now. However, photoactive hybrid layers of
material combinations such as rr-P3HT and SiNWs still require further exploration as
candidates for solar cell (SC) fabrication, due to favourable optical absorption and
charge carrier mobility associated with them respectively. The ultimate goal of the study
is to fabricate ITO/PEDOT:PSS/rr-P3HT:SiNWs/Al SCs with different SiNWs content
and investigate the different parameters or factors influencing the performance of these
cells. The vertically aligned SiNW arrays on a Si wafer were synthesised via metal
assisted chemical etching (MACE) and a method of chemically detaching these wires
was developed. The average length and the diameter of the SiNWs obtained were 4.5
μm and 0.2 μm, respectively. Different weight ratios of as-synthesised SiNWs were then
incorporated within rr-P3HT to form different hybrid solutions, i.e. rr-P3HT: 0.3 wt%
SiNWs, rr-P3HT: 0.7 wt% SiNWs and rr-P3HT: 1.3 wt% SiNWs. In addition, a pure rr-
P3HT solution was made for reference purposes. SEM characterisation shows that the
SiNWs are randomly distributed across the active area, and that the film becomes
progressively inhomogeneous upon addition of SiNWs, whereas the TEM
characterisation revealed that there is no chemical interaction between the rr-P3HT and
SiNWs. The UV-Vis and PL spectra suggest that there are changes in absorption and
emission characteristics upon SiNW incorporation into the rr-P3HT matrix, which may
have impacted the charge transfer .The electrical properties of the different hybrid films
were probed using Hall Effect measurements, which revealed that the conductivity
increases with the increase in the concentration of nanowires (NWs). The increase in
conductivity upon the addition of SiNWs in the rr-P3HT matrix was related to an
increase of the mobility (μ) of charge carriers in the hybrid films.
Description
>Magister Scientiae - MSc
Keywords
Photovoltaics, Spin coating, Electric properties, Optical properties, Optimisation