Organizational Unit:
University Center of Excellence for Photovoltaics
University Center of Excellence for Photovoltaics
Permanent Link
Research Organization Registry ID
Description
Previous Names
Parent Organization
Parent Organization
Includes Organization(s)
ArchiveSpace Name Record
Publication Search Results
Now showing
1 - 3 of 3
-
ItemImplementation of a Homogenous High-Sheet-Resistance Emitter in Multicrystalline Silicon Solar Cells(Georgia Institute of Technology, 2005-01) Yelundur, Vijay ; Nakayashiki, Kenta ; Hilali, Mohamed M. ; Rohatgi, AjeetSolar cell efficiency enhancement resulting from the implementation of a high-sheet-resistance emitter (95 Ω/sq.) in multicrystalline silicon solar cells with screenprinted contacts is demonstrated in this paper. Solar cells on low-cost String Ribbon Si from Evergreen Solar, Baysix mc-Si from Deutsche Solar, and high-quality float zone silicon with 45 Ω/sq. and 95 Ω/sq. phosphorus-doped n+- emitters are fabricated with RTP-fired screen-printed contacts and characterized to asses the impact of a highemitter-sheet resistance emitter on cell performance. Screen-printed mc-Si solar cells show an improvement in Voc of 4-5 mV in most cases that is attributed to the use of the high-sheet-resistance emitter. An appreciable increase in Jsc by as much as 1.0 mA/cm(2) is also observed due to enhanced blue response identified by internal quantum efficiency measurement.
-
ItemInvestigation of High-Efficiency Screen-Printed Textured SI Solar Cells with High Sheet-Resistance Emitters(Georgia Institute of Technology, 2005-01) Hilali, Mohamed M. ; Nakayashiki, Kenta ; Ebong, Abasifreke ; Rohatgi, AjeetIn this study it is found that the efficiency enhancement (Δη) resulting from the use of a 100 Ω/sq emitter instead of a conventional 45 Ω/sq emitter is substantially enhanced further by surface texturing. This enhancement is greater for textured cells by at least ~0.4% absolute over the enhancement for planar cells, and is mainly due to the greater difference in the front-surface recombination velocity (FSRV) between the high and low-sheet-resistance emitter textured cells. A FSRV of 60,000 cm/s resulted in a reasonably good V(oc) of ~642 mV for the 100 Ω/sq emitter textured cell. Our investigation of the Ag-Si contact interface shows a more regular distribution of Ag crystallite precipitation for the textured emitter (mainly at the peaks of the texture pyramids). The high contact-quality resulted in a series resistance of 0.79 Ω-cm, a junction leakage current of 18.5 nA/cm(2) yielding a FF of 0.784. This resulted in a record high-efficiency 4 cm(2) screen-printed cell of 18.8% (confirmed by NREL) on textured 0.6 Ω-cm FZ, with single-layer antireflection coating.
-
ItemRecord-High-Efficiency Solar Cells on Multicrystalline Materials Through Understanding and Implementation of RTP-Enhanced SiNx-induced Defect Hydrogenation(Georgia Institute of Technology, 2004-01) Rohatgi, Ajeet ; Kim, Dong Seop ; Yelundur, Vijay ; Nakayashiki, Kenta ; Upadhyaya, A. D. ; Hilali, Mohamed M. ; Meemongkolkiat, VichaiThis paper presents results on five record-high-efficiency 4 cm(2) solar cells on three different multicrystalline silicon materials through effective hydrogen passivation of bulk defects during cell processing. Silicon ribbon solar cell efficiencies of 18.2% and 17.9% were achieved on EFG and String Ribbon Si cells fabricated with photolithography front contacts, screen-printed Al-doped back surface field, and double layer anti-reflection coating. In addition, high-efficiency, screen-printed, manufacturable cells were achieved on HEM (16.9%), EFG (16.1%), and String Ribbon (15.9%) Si. It is found that proper implementation of a fast co-firing of front and back screen-printed contacts in a belt furnace can significantly enhance the bulk lifetime to ~100 μs and simultaneously produce high quality contacts with fill factors approaching 0.78. The firing process involves fast ramp-up and cooling rates to enhance PECVD SiN(x)-induced hydrogen passivation of defects and the quality of Al back surface field.