A round robin study of polymer solar cells and small modules across China

A round robin study across 15 laboratories in China was carried out using single junction devices with an active area of 1 cm2 and differently sized small module with an active area of 20 and 24 cm2 respectively. The devices represented the state of the art in terms of processing as they did not employ indium or vacuum and were prepared using only printing and coating techniques on flexible substrates. The devices were studied in their flexible form and thus approach the vision of what the polymer solar cell is. The main purpose of the work was to establish and chart geographic and cultural differences in what constitutes a competent IV-characterization procedure and also to establish the spread in measured data across the globe. The main finding is that efficiency data deviated up to 30% from the mean while an overall relative standard deviation of 12% was observed. Collating this spread with previous findings points toward a seemingly region-independent i.e. global observation of the uncertainty in the IV-characterization of a polymer solar cell. Finally, we highlight what might be done to improve the accuracy of the reported data.