https://www.sciencedaily.com/releases/2018/05/180529103558.htm

OPVs are made from inexpensive, lightweight materials, and benefit from good safety as well as easy production. However, their power conversion efficiencies (PCEs) -- the ability to convert light into electricity -- are still too low for full-scale commercialization.

The PCE depends on both the organic and the polymer layer. Traditionally, chemists have experimented with different combinations of these by trial-and-error, leading to a lot of wasted time and effort.