Science
Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/1
Browse
3 results
Search Results
Item EFFECT OF THE TYPE OF CONDUCTING GLASS SUBSTRATE ON ELECTRODEPOSITED CdS AND CdTe THIN FILMS(Solar Asia 2018 Int. Conf. National Institute of Fundamental Studies, Kandy, Sri Lanka, 2018) De Alwis, A.C.S.; Atapattu, H.Y.R.; De Silva, D.S.M.Thin film CdS/CdTe solar cells produced by the technique of electrodeposition (ED) on conducting glass substrates have become one of the leading applications of photovoltaics due to its high energy conversion efficiency via absorption of solar energy in a wider range within the solar spectrum. In previous studies, it has been established that the quality of CdS and CdTe thin films depends upon several growth parameters namely; the deposition potential, precursor concentrations & their ratios, pH of the electrolyte, deposition temperature and the rate of stirring of the electrolyte during the process of ED. In addition, the effect of conducting glass substrate on properties of the deposited material has been identified as a decisive consequence in achieving photoactive materials. Hence, the present study was carried out to determine the effect of the type of glass substrates on electrodeposited CdS and CdTe thin films. In this study, glass substrates coated with different transparent conducting oxide (TCO) layers namely; fluorine-doped tin oxide (FTO) and indium tin oxide (ITO) were considered and for each type of TCO layer two different sheet resistances (FTO: 7 vs. 13 Ω/sq and ITO: 7 vs. 15 Ω/sq) were taken into account. CdS thin layers were electrodeposited on these four types of glass substrates using an electrolyte consisted of CdCl2 (0.1 mol/L) and Na2S2O3 (0.01 mol/L) as Cd and S precursors respectively at pH of 1.7 and temperature of 55 °C for 30 minutes under cathodic deposition potential (CDP) of 650 mV vs. a saturated calomel electrode (SCE). Out of twelve replicates of CdS depositions on each type of glass substrate, six replicates from each type (glass/TCO/CdS) were conveyed for electrodeposition of CdTe thin films in an electrolyte consisted of CdSO4 (1.0 mol/L) and TeO2 (1.0 mmol/L) as Cd and Te precursors respectively at pH of 2.2 and temperature of 65 °C for 3 hours under CDP of 660 mV vs. SCE. The resulting CdS and CdTe thin films were heat treated at 400 °C for 10 minutes after each deposition and subsequent studies namely; UV-Vis absorption spectroscopy, photo-electrochemical cell analysis, scanning electron microscopy and X-ray diffraction spectroscopy were carried out to determine the optical, electrical, morphological and structural properties respectively of glass/TCO/CdS and glass/TCO/CdS/CdTe samples produced. As results revealed, the CdS and CdTe layers deposited on glass/FTO (7 Ω/sq) substrates have exhibited better optoelectronic qualities and the study further confirmed the dependence of material quality on type of the conducting glass substrate. Hence, the individual growth parameters optimization for each type of TCO glass substrate is an essential step in electrodeposition of good quality CdS and CdTe thin films for solar cell fabrications.Item Influence of the type of conducting glass substrate on the properties of electrodeposited CdS and CdTe thin films(Journal of Materials Science: Materials in Electronics (2018) 29:12419-12428 https://doi.org/10.1007/s10854-018-9358-8, 2018) De Alwisl, A.C.S.; Atapattu, H.Y.R.; De Silva, D.S.M.Owing to the greater efficiency in energy conversion by absorbing energy in a wider range of the solar spectrum, thin film CdSICdTe solar cells have been popularized as a prominent application of photovoltaics and the technique of electrodeposi-tion (ED) is an ideal method available for producing both CdS and CdTe materials upon its outrivaled simplicity, low cost, scalability and manufacturability. Typically the quality of these deposited thin films depends on several growth parameters and amid them, the type of conducting glass substrate plays a crucial role. This study is focused on the influence of conduct-ing glass substrate on the properties of electrodeposited CdS and CdTe thin films. Two types of glass substrates coated with different transparent conducting oxide (TCO) layers namely; fluorine-doped tin oxide (FTO) and indium tin oxide (ITO) having different sheet resistances (FTO: 7 and 13 Disq and ITO: 7 and 15 Disq) were considered. CdS and CdTe materials were electrodeposited respectively on each of these types of TCO layers using a three electrode electrolytic system under a consistent set of growth parameters which has been pre-optimized with respect to FTO having sheet resistance of 7 afsq. The deposited CdS and CdTe thin layers were subsequently heat treated and characterized to understand their optical, electri-cal, morphological and structural properties. Accordingly, CdS and CdTe semiconductor materials deposited on glass+10 (7 .0./sq) substrates have exhibited better optoelectronic qualities and hence, endorse the requirement of individual growth parameter optimization for each type of TCO glass substrate for the production of good quality CdS and CdTe thin films in photovoltaic device fabrications.Item Electrodeposited Cu2O homojunction solar cells: Fabrication of a cell of high short circuit photocurrent(Elsevier, 2016) Wijesundera, R.P.; Gunawardhana, L.K.A.D.D.S.; Siripala, W.A Cu2O homojunction solar cell was fabricated using a consecutive electrodeposition method of deposition of an n-Cu2O film followed by a p-Cu2O film, in two different acetate baths. Both n-type and p-type film growth conditions were optimized separately to yield high photocurrents in a photoelctrochemical (PEC) cell. Further, the resulted bi-layer films were investigated in the PEC for the verification of the formation of the p-n homojunction. In addition, p-Cu2O film surfaces of the bi-layers were sulphided using Na2S and (NH4)2S in order to improve the photoresponse of the homojunction before depositing a Au film for the solar cell device. The structural, morphological and optoelectronic properties of the Cu2O films were investigated using X-ray diffraction (XRD), scanning electron micrographs (SEMs), dark and light current–voltage (I-V) and spectral response measurements and observed that the films are of good quality. Incident photon to current efficiency (IPCE) and I-V characteristics of the solar cell device demonstrated that the Cu2O homojunction can produce a high short circuit current density Jsc. However, the overall conversion efficiency of the device is low due to poor fill factor and Voc. The solar cell characteristics of the structure Ti/n-Cu2O/p-Cu2O/Au were Voc=287.0±0.1 mV, Jsc=12.4±0. 1 mA/cm2, FF=25±2% and η=0.89±0.02%, under AM 1.5 illumination. The record high Jsc value of the device demonstrates the prospect being improved the efficiency of Cu2O homojunction solar cells by optimizing deposition, pretreatment and post treatment processes.