Cite this article:
Swami and Tiwari (2014). Optical Characteristics of PCDTBT: PCBM70 Organic Solar Cells. Journal of Ravishankar University (Part-B: Science), 27(1), pp. 115-121.
Optical Characteristics of PCDTBT: PCBM70 Organic Solar Cells
Rashmi Swami* and Sanjay
Tiwari
Photonics Research Laboratory,
School of Studies in Electronics, Pt. Ravishankar Shukla University, Raipur - 492010
*corresponding Author: rashmi.swami3@gmail.com
[Received
2 April 2014; accepted 21 April 2014]
Abstract. We herein report on the improved photovoltaic (PV)
effects of using
a polymer bulk-heterojunction (BHJ) layer that consists of a low-band gap electron donor
polymer of poly(N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2 thienyl- 2',l',3'-benzothiadiazole))
(PCDTBT) and an acceptor of [6,6]-phenyl C70 butyrlc
acid methyl ester (PCBMro). The characteristics investigated include
refractive index, extinction coefficient, optical conductivity,
absorbance/transmittance/reflectance and their variation with wavelength, Absorbance/transmittance/reflectance
are calculated using extended net radiation method and coding is done in MATLAB.
Refractive index, extinction coefficient, absorption coefficient, absorbance of
PCDTBT: PCBM70 blend film shows variations in vi"ible range (350
run - 650 nm). Refractive index of PCDTBT: PCBM70increases from wavelength 450
run to 612 nm and reaches to its maximum
value 2.2883 at 610 run wavelength. Extinction
coefficient of PCDTBT:PCBM70 has maximum
value of 0.4408 at 300 nm wavelength then decreases with increase in
wavelength. The
PCDTBT:PCBM70 PV showed strong absorption bands and optical conductivity in the
visible range from 350 to 650 run, extending to an absorption and conductivity onset
at 800 nm, and containing two distinct but broad absorption bands and conductivity
band centered at ca. 380-420 run and ca. 475-570 nm. We get high optical conductivity
in the region where absorbance of PCDTBT:PCBM70 OSC is high because
α ). PCDTBT:PC7oBM OSC shows more than 50% transmittance at
wavelengths longer than 570 run i.e. transmittance is high in infrared region and
sharp fall below 350 run because of strong
absorbance in this region, Reflectance i11 less than 17% in visible and infrared region.
Keywords: bulk heterojunction, organic solar cell, absorbance,
transmittance, reflectance
NOTE: Full version
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