Barrier coatings for thin film solar cells: final subcontract report, September 1, 2002-January 30, 2008

Original publisher: Golden, Colo. : National Renewable Energy Laboratory, U.S. Dept. of Energy, Office of Energy Efficiency and Renewable Energy, [2010] OCLC Number: (OCoLC)586059491 Subject: Photovoltaic cells -- Research. Excerpt: ... the A-factor would change very little while the Jo value increased by two orders of magnitude. The relatively constant A-factor suggests that the dominant recombination center is the same in both cases, but the increase in Jo indicates the density of recombination centers increased by two orders of magnitude. Two encapsulated circuits with appropriate P-Layers were returned to SSI for measurement with their simulator after being subjected to 1000 hours at 60ºC / 90 % RH. I-V characteristics of these circuits were measured by SSI before sending them to PNNL. Barrier coatings were then applied to the circuits and then they were stressed in an environment of 60ºC / 90 % RH for 1000 hours. The devices were then returned to SSI where they were characterized. In both cases, the circuit efficiencies increased, even after being stressed at 60ºC / 90 % RH for 1000 hours ( see Table 2 ). SSI also subjected these encapsulated circuits to UV testing. Although some blistering occurred, circuit 22-9 actually improved in performance as the power increased to 0.688 watts. The power produced by Circuit 22-4 decreased to 0.498 watts. More studies are required before we can characterize the effects of UV, but these results were very encouraging. However, the effect of light-induced transients has to be better characterized. Table 2. Measurements By Shell Solar Circuit P ( Watts ) max Bare Circuit 22-4 0.525 Encapsulated ( and 1000 hrs @ 60 / 90 ) 22-4 0.582 Bare Circuit 22-9 0.592 Encapsulated ( and 1000 hrs @ 60 / 90 ) 22-9 0.631 Damp Heat Studies in 85C / 85 % RH As this program progressed, it became clear that damp heat conditions defined by 85ºC and 85 % relative humidity were being established as the appropriate stress conditions. In fact, t...