| Summary: | TiO2 solution of 1% and 5% was added into the MEH-PPV dissolved in
chlorobenzene. MEH-PPV and PCBM materials were mixed with weight ratio of
1:1, 1:2 and 1:4 then each ratio was dissolved in chlorobenzene. These solutions
were deposited on ITO substrates using spin coating method to form a blendedlayer.
Absorbance of layer was determined using the UV-Vis spectrophotometer
while I-V characteristics of layer were measured by a Keithley of 2602A model.
Internal parameters of solar cell were determined by the best fitting between
experimental and modelling results. We performed modelling using two
approaches i.e. linear profile near breakdown voltage and Particle Swarm
Optimization (PSO).
MEH-PPV:TiO2 blend layers absorbed light at wavelengths of less than 400
and 450 to 550 nm. Energy gap of TiO2 and MEH - PPV was (3.7 ± 0.2) eV and
(2.1 ± 0.1) eV which is obtained from analysis of absorbance vs wavelength
curves. I-V characterization showed that the addition of TiO2 increased
conductivity. It is considered that the addition of TiO2 in the polymer MEH-PPV
can reduce the barrier of electron charge carrier between the polymer and Al
electrode. In addition, the absorption spectra of the mixed layer showed a
superposition of spectra of the pure MEH-PPV and pure PCBM layer. The energy
band gap of the pure PCBM layer was (2.3 ± 0.1) eV. Based on the I-V
characterization, the best efficiency was obtained in blend MEH-PPV:PCBM =
1:2. The addition of PCBM in the polymer MEH-PPV is also reduces the barrier
of electron charge carrier between the polymer and Al electrode. The linear and
PSO approaches have similar trend of internal parameters thought different values
of internal parameters. Furthermore, the addition of PCBM can decrease the series
resistance. Meanwhile, the intensity of illumination increase that cause the
photocurrent density and saturation current increase. As consequence, series and
parallel resistance decreases with the increase of light intensity.
Key words: MEH-PPV, PCBM, TiO2, Solar cells parameters internal
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