Sri Lankan Journal of Physics, Volume 9, March 2008.
Determination of electrochemical stability window of a polyacrylonitrile
based polymer system for different electrodes
Kumudu Perera*, K.P. Vidanapathirana and M.A.K.L. Dissanayake
Solid polymer electrolytes are considered to be very appealing candidates for numerous applications such as batteries, artificial muscles and super capacitors. For applications, the voltage limits between the oxidation and reduction are very important. The voltage limits are taken as the positions where oxidation and reduction occurs. Those two positions can be traced using a cyclic voltammogram. The solid polymer electrolyte under investigation comprised of polyacrylonitrile (PAN), ethylene carbonate (EC). propylene carbonate (PC) and lithium trifluoromethanesulfoinate (LiCF3SO3 – LiTF). All the preparation steps were carried out in side an Argon filled glove box. Electrolyte film was sandwiched in a brass sample cell holder in between a Li electrode and one of an inert electrode made of stainless steel, nickel, platinum, copper and aluminium. Lithium was used as the reference and counter electrodes while the inert electrode was used as the working electrode. Cyclic voltammetry measurements were taken in the potential range, 2.0 V – 4.9 V vs Li. A good stability window was seen when the stainless steel electrodes were used.
Sri Lankan Journal of Physics, Volume 9, March 2008.
Properties of solid-state ZnO|dye|CuCNS solar cell
P.M. Sirimanne* and J.B. Zhang
Hybrid ZnO films were prepared via a single-step electrochemical process. Extraction of organic component from the hybrid films resulted tiny ZnO columns perpendicular to the substrate. A Semiconductor hetro Junction was prepared by depositing CuSCN on ZnO films. The maximum photocurrent of 0.36 mAcm-2 and photovoltage of 290 mV were observed for the solid-state cell fabricated by sandwiching organic dye mercurochrome in between ZnO and CuSCN films.
Sri Lankan Journal of Physics, Volume 9, March 2008.
Characterization of electrochemically prepared CuSCN films
and their capabilities of application in dye sensitized photovoltaic cells
P.M. Sirimanne* and J.B. Zhang
CuCNS was deposited on conducting glass substrates by cathodic electrochemical technique using rotating disc electrode. CuCNS films exhibited transparency over 85% for visible light. High transparency of these films suggests capability of utilization as an optical window in photovoltaic cells. Cathodic photocurrent was observed on sensitized CuCNS electrodes when in contact with an electrolyte. An enhancement in photocurrent was observed under back wall mode than front wall mode illumination on photocathode.
Sri Lankan Journal of Physics, Volume 9, March 2008.
Enhanced photovoltaic effects of dye-sensitized solar cells
of SnO2 surface modified with gold nano particles
G.L.M.P Aponsu, R.C.L de Silva, and V.P.S Perera*
The photovoltaic properties of dye-sensitized solar cells of SnO2 are improved by depositing gold nano-particles on the surface of SnO2 particles. The enhancement of the efficiency is attributed to increment of both the photocurrent and the photo voltage of the cells. This is described by the shift of the conduction band edge of SnO2 to a higher energy level when SnO2 particles are in contact with gold nano-particles.
Sri Lankan Journal of Physics, Volume 9, March 2008.
Electrodeposition of p-type, n-type and p-n Homojunction
Cuprous Oxide Thin Films
K.M.D.C. Jayathileke, W. Siripala* and J.K.D.S. Jayanetti
Potentiostatic electrodeposition of cuprous oxide (Cu2O) thin
films in aqueous acetate baths was investigated to study the conduction type,
n-type or p-type, and the p-n homojunction formation of the films, using photocurrent
spectral response and capacitance-voltage measurements to determine the conduction
type. The study reveals that not only the pH value but also the cupric ion concentration
of the acetate bath determines the conduction type of the films. Electrodeposition
of p-n homojunction of Cu2O is possible with a single or a two step electrodeposition.
Both parameters of the deposition bath, pH and cupric ion concentration, can
be adjusted to control conduction type and p-n homojunction formation of Cu2O
films.
Sri Lankan Journal of Physics, Volume 9, March 2008.
Thermodynamic investigation of solar energy conversion into
work
W.T.T. Dayanga and K.A.I.L.W. Gamalath*
Using a simple thermodynamic upper bound efficiency model for the conversion of solar energy into work, the best material for a converter was obtained. Modifying the existing detailed terrestrial application model of direct solar radiation to include an atmospheric transmission coefficient with cloud factors and a maximum concentration ratio, the best shape for a solar concentrator was derived. Using a Carnot engine in detailed space application model, the best shape for the mirror of a concentrator was obtained. A new conversion model was introduced for a solar chimney power plant to obtain the efficiency of the power plant and power output.