Sudha Kartha, C; Vijayakumar, K P; Rajeshmon, V G; Vimalkumar, T V; Poornima, N(Hindawi Publishing Corporation, January 6, 2013)
[+]
[-]
Abstract:
This work projects photoluminescence (PL) as an alternative technique to estimate the order of resistivity of zinc oxide (ZnO) thin
films. ZnO thin films, deposited using chemical spray pyrolysis (CSP) by varying the deposition parameters like solvent, spray rate,
pH of precursor, and so forth, have been used for this study. Variation in the deposition conditions has tremendous impact on the
luminescence properties as well as resistivity. Two emissions could be recorded for all samples—the near band edge emission (NBE)
at 380 nm and the deep level emission (DLE) at ∼500 nm which are competing in nature. It is observed that the ratio of intensities
of DLE to NBE (𝐼DLE/𝐼NBE) can be reduced by controlling oxygen incorporation in the sample. 𝐼-𝑉 measurements indicate that
restricting oxygen incorporation reduces resistivity considerably. Variation of 𝐼DLE/𝐼NBE and resistivity for samples prepared under
different deposition conditions is similar in nature. 𝐼DLE/𝐼NBE was always less than resistivity by an order for all samples.Thus from
PL measurements alone, the order of resistivity of the samples can be estimated.
Description:
International Journal of Photoenergy
Volume 2013, Article ID 105796, 9 pages
Sudha Kartha, C; Vijayakumar, K P; Angel, Susan Cherian; Abe, T; Kashiwaba, Y(Elsevier, 2012)
[+]
[-]
Abstract:
Thin film solar cells having structure CuInS2/In2S3 were fabricated using chemical spray pyrolysis (CSP) technique
over ITO coated glass. Top electrode was silver film (area 0.05 cm2). Cu/In ratio and S/Cu in the precursor solution
for CuInS2 were fixed as 1.2 and 5 respectively. In/S ratio in the precursor solution for In2S3 was fixed as 1.2/8. An
efficiency of 0.6% (fill factor -37.6%) was obtained. Cu diffusion to the In2S3 layer, which deteriorates junction
properties, is inevitable in CuInS2/In2S3 cell. So to decrease this effect and to ensure a Cu-free In2S3 layer at the top of
the cell, Cu/In ratio was reduced to 1. Then a remarkable increase in short circuit current density was occurred from 3
mA/cm2 to 14.8 mA/cm2 and an efficiency of 2.13% was achieved. Also when In/S ratio was altered to 1.2/12, the
short circuit current density increased to 17.8 mA/cm2 with an improved fill factor of 32% and efficiency remaining
as 2%. Thus Cu/In and In/S ratios in the precursor solutions play a crucial role in determining the cell parameters
Sudha Kartha, C; Vijayakumar, K P; Sreekumar, K; Maheshkumar, M V; Rajesh Menon, M R(WILEY-VCH Verlag GmbH & Co, September 22, 2011)
[+]
[-]
Abstract:
In this paper, we report the results of investigations on the
potential of spray pyrolysis technique in depositing electron
selective layer over larger area for the fabrication of inverted
bulk-heterojunction polymer solar cells. The electron selective
layer (In2S3) was deposited using spray pyrolysis technique and
the linear heterojunction device thus fabricated exhibited good
uniformity in photovoltaic properties throughout the area of the
device. An MEH-PPV:PCBM inverted bulk-heterojunction
device with In2S3 electron selective layer (active area of
3.25 3.25 cm2) was also fabricated and tested under indoor
and outdoor conditions. Fromthe indoor measurements employing
a tungsten halogen lamp (50mW/cm2 illumination), an opencircuit
voltage of 0.41V and a short-circuit current of 5.6mA
were obtained. On the other hand, the outdoor measurements
under direct sunlight (74mW/cm2) yielded an open-circuit
voltage of 0.46V and a short-circuit current of 9.37mA
Sudha Kartha, C; Nimmi, K P; Sreekumar, K; Rani, Joseph; Pramitha, V(Wiley Online Library, January 7, 2012)
[+]
[-]
Abstract:
Holographic grating with good storage
life in poly(vinyl alcohol) based photopolymer film, prepared
by gravity settling method, with reduced concentration
of the dye was found to give good diffraction
efficiency without crosslinking. The material was found
to show good diffraction efficiency and sensitivity (75%
diffraction efficiency at exposure energy of 80 mJ/cm2).
The shelf life of the photopolymer solution could be
improved by storage at a temperature 4 C in refrigerator
Description:
Journal of Applied Polymer Science, Vol. 125, 1238–1243 (2012)
