Bio

DR. WAITA SEBASTIAN M

Personal Information

Areas Of Specialization

Condensed Matter Physics (Materials for Solar Energy conversion)

Research Interests

Photovoltaic (Solar Energy) Research & Training
 Materials for Solar Energy conversion
 Nanotechnology for Technology Applications
 Thin film characterization

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Publications


2014

Simiyu, J, WAITA SEBASTIAN, Robinson Musembi, Ogacho A, Aduda B.  2014.  Promotion of PV Uptake and Sector Growth in Kenya through Value Added Training in PV Sizing, Installation and Maintenance. Energy Procedia . 57 :817–825.

2013

Sebastian, W, Justus S, Robinson M, Alex O.  2013.  Promoting photovoltaic energy in Kenya through training. http://www.epsnews.eu/2013/03/photovoltaic-energy-in-kenya.
Fanuel Mugwang'a Keheze, Karimi Mwangi Patrick, Walter N, WAITA SEBASTIAN.  2013.  Copper Based Solar Cell Materials. EPS. , London: LAP LAMBERT Academic Publishing
WAITA, SEBASTIAN.  2013.  Performance of TiO2/In(OH)iSj/Pb(OH)xSy Composite ETA Solar Cell Fabricated from Nitrogen Doped TiO2 Thin Film Window Layer. International Journal of Materials Engineering . 3(2):11-16.

2012

Ayieko, CO, Musembi RJ, Waita SM, Aduda BO, Jain PK.  2012.  Performance of TiO2/In(OH)iSj/Pb(OH)xSy Composite ETA Solar Cell Fabricated from Nitrogen Doped TiO2 Thin Film Window Layer. AbstractPerformance of TiO2/In(OH)iSj/Pb(OH)xSy Composite ETA Solar Cell Fabricated from Nitrogen Doped TiO2 Thin Film Window Layer

In this work, Titanium Dioxide (TiO2) thin films were prepared by spray pyrolysis and thermally annealed at 400 oC. The films were characterized as deposited (no annealing) as well as after annealing. Optical studies showed that the energy band gap of the films was lowered from 3.25 eV to 2.90 eV on Nitrogen (N2) doping. The reduction in energy band gap was attributed to the introduction of N2 impurity states on the bands (conduction band and or valence band). The effect of N2 doping of Titanium Dioxide window layer on the efficiency of the ETA TiO2/In(OH)iSj/Pb(OH)xSy solar cell was investigated using a conventional current-voltage (I-V) technique. The photovoltaic conversion efficiency (η) increased from 1.06% for the solar cell with undoped films to 1.32% for the solar cell with N2-doped films. The increase in photovoltaic conversion efficiency on doping was attributed to increased light absorption due to the Nitrogen doping.

Mugwang’a, FK, Karimi PK, Njoroge WK, Omayio O, Waita SM.  2012.  Optical Characterization of Copper Oxide Thin Films Prepared By Reactive Dc Magnetron Sputtering For Solar Cell Applications. AbstractOptical Characterization of Copper Oxide Thin Films Prepared By Reactive Dc Magnetron Sputtering For Solar Cell Applications

— Cu2O thin films have been deposited using reactive dc magnetron sputtering technique using an Edward Auto 306 Magnetron Sputtering System. Transmittance and reflectance data in the range 300 nm-2500 nm were obtained using UV-VIS NIR Spectrophotometer Solid State 3700 DUV for all the thin films samples that were prepared. Transmittance values of above 70% were observed. The optical measurements were simulated using SCOUT 98 software to determine optical constants and optical bad gap of the thin. The optical properties in these films were varied by varying oxygen flow rate at constant powerof 200 W. Optical studies show a direct allowed transition and a shift in the optical absorption edge as the oxygen flow rate varies at constant argon flow rate and other deposition parameters. These results show that single phase Cu2O thin films can be synthesized at a relatively low substrate temperature using the reactive dc magnetron sputtering technique. Band gap values of 1.62 eV –2.54 eV is observed. The surface sheet resistivities at room temperature of 298 K were found to vary with the deposition parameters and film thickness. Urbach energy varied between 0.6 ×10-4 to 1.92 ×104

WAITA, SEBASTIAN.  2012.  Dark J-V Characterization of a Dye-Sensitized Module. International Journal of Professional Practice (IJPP),. 3(1&2):165-168.: International Journal of Professional AbstractWebsite

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WAITA, SEBASTIAN.  2012.  Structural and Optical Characterization of Nitrogen Doped TiO2 Thin Films Deposited by Spray Pyrolysis on Fluorine Doped Tin Oxide (FTO) Coated Glass Slides. International Journal of Energy Engineering. 2(3):67-72.: International Journal of Energy Engineering AbstractWebsite

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WAITA, SEBASTIAN.  2012.  Application of Dye-Sensitized Solar Cell Technology in the Tropics: Effects of Radiation Intensity and Temperature on DSSC Performance. International Journal of Advanced Renewable Energy Research (IJARER). 1(2):17-25.: International Journal of Advanced Renewable AbstractWebsite

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WAITA, SEBASTIAN.  2012.  Application of Dye-Sensitized Solar Cell Technology in the Tropics: Effects of Air Mass on Device Performance. International Journal of Renewable Energy Research (IJRER). 2(3):369-375.: International Journal of Renewable Energy Research AbstractWebsite

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2011

WAITA, SEBASTIAN.  2011.  Workshop on Research Grant and Project Grant Training on proposal writing, 09/26-30/2011. Chiromo Conference Centre, University of Nairobi. , NAIROBI: Elsevier Abstract

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WAITA, SEBASTIAN.  2011.  Training on Photovoltaic Application and Installations, 4-5 August. PV TRAINING AND INSTALLATION. , Department of Physics, University of Nairobi: Elsevier Abstract

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2010

WAITA, SEBASTIAN.  2010.  Extraction of Resistances in Dye Sensitized Solar Cells Fabricated from Obliquely Sputtered TiO2 Films,, 8-9 JULY. Opto-Electronics Devices: Their potential for Sustainable Development, conference held at the Department of Physics, University of Nairobi. , DEPT OF PHYSICS, UON: Elsevier Abstract

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WAITA, SEBASTIAN.  2010.  Electrochemical Characterization of TiO2 Blocking Layers Prepared by Reactive DC Magteron Sputtering, 3-7 MAY. African School on Nanoscience for solar Energy Conversion, Addis Ababa, Ethiopia.. , AKAKI CAMPUS, ADDIS ABABA: Elsevier Abstract

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2009

WAITA, SEBASTIAN.  2009.  Optical characterization of sputtered TiO2 compact under layers for dye-sensitized solar cell applications, 3-5 OCTOBER. 1st International conference on Solar Energy Materials Dar Es Salaam, Tanzania.. , Dar es Salaam: Elsevier Abstract

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WAITA, SEBASTIAN.  2009.  Electrochemical characterization of TiO2 blocking layers prepared by reactive DC magnetron sputtering. Journal of the Electroanalytical Chemistry 637, 79-83.. 637: Elsevier AbstractWebsite

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2008

Waita, SM, Aduda BO, Mwabora, J.M; Niklasson GA, Lindquist SE, Granqvist CG.  2008.  DC sputter deposited TiO2 photoelectrodes: Effect of deposition angle on the efficiency of dye sensitized solar cell..

2007

WAITA, SEBASTIAN.  2007.  Columnar and passivated nanoporous TiO2 based excitonic solar cell, 20-27 January. US/Africa workshop on frontiers in Material Science, Abuja, Nigeria.. , Abuja, Nigeria: Elsevier Abstract

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WAITA, SEBASTIAN.  2007.  Charge transport in bare and MgO-coated TiO2 thin films and in dye-sensitized solar cells: effect of film thickness, 31st July-3rd Au. ICE2007, International conference on Electroceramics, Arusha, Tanzania.. , Arusha, Tanzania: Elsevier Abstract

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WAITA, SEBASTIAN.  2007.  Electron Ttransport and Recomination in Dye Sensitized Solar Cells Fabricated from Obliquely Sputtered and Thermally Annealed TiO2 films. Journal of the Electroanalytical Chemistry 605(2), 151-156.. : Elsevier AbstractWebsite

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WAITA, SEBASTIAN.  2007.  Effect of nitration on pressed TiO2 photoelectrodes for dye-sensitized solar cells. African Journal of Science and Technology,Vol. 8 No. 2, pp 63-71. : ANSTI AbstractWebsite

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2006

WAITA, SEBASTIAN.  2006.  Nanostructured TiO2 for dye sensitized photoelectrochemical solar cells, 14-25th August. ICTP-NCNNC . , Beijing, China: Elsevier Abstract

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WAITA, SEBASTIAN.  2006.  Performance of Dye Sensitized Solar Cells Fabricated From Obliquely DC Sputtered TiO2 Films. African Journal of Science and Technology Vol. 7, No. 2, 125-138. : ANSTI AbstractWebsite

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2000

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