Hand-drawn organic photovoltaics

Over the past three decades, organic LEDs have gone from promising prototypes to commercial digital displays and light sources (see Physics Today, November 2008, page 26 and February 2013, page 10). Perhaps it’s little surprise that organic photovoltaics (OPVs) are starting down a similar path. OPVs offer the promise of flexible, large-area, and low-cost solar cells and photodetectors. In the lab, test samples are usually prepared by spin-coating: A small amount of solution containing a mix of organic semiconductors is placed on a substrate, and the substrate is spun rapidly to spread the solution into a thin film.