It should be noted that, because of the large number
of processing steps and the batch processing adopted
by our university research laboratory, there is a wide
variation in the cell efficiencies (7% to 10.7%), depending
on the batch. In the best batch to date, the 3 cells had
power conversion efficiencies of 10.4%, 10.1%, and
10.7%, yielding an average value of 10.4%.