Understanding the degradation mechanisms of organic photovoltaics is particularly important, as they tend to degrade faster than their inorganic counterparts, such as silicon and cadmium telluride. An overview is provided here of the main degradation mechanisms that researchers have identified so far that cause extrinsic degradation from oxygen and water, intrinsic degradation in the dark, and photo-induced burn-in. In addition, it provides methods for researchers to identify these mechanisms in new materials and device structures to screen them more quickly for promising long-term performance. These general strategies will likely be helpful in other photovoltaic technologies that suffer from insufficient stability, such as perovskite solar cells. Finally, the most promising lifetime results are highlighted and recommendations to improve long-term performance are made. To prevent degradation from oxygen and water for sufficiently long time periods, OPVs will likely need to be encapsulated by barrier materials with lower permeation rates of oxygen and water than typical flexible substrate materials. To improve stability at operating temperatures, materials will likely require glass transition temperatures above 100 °C. Methods to prevent photo-induced burn-in are least understood, but recent research indicates that using pure materials with dense and ordered film morphologies can reduce the burn-in effect.
Mateker WR, McGehee MD (2016) Progress in Understanding Degradation Mechanisms and Improving Stability in Organic Photovoltaics. Advanced Materials 29: 1603940. Available: http://dx.doi.org/10.1002/adma.201603940.
The authors would like to thank Craig Peters, Toby Sachs-Quintana, Thomas Heumueller, Rongrong Cheacharoen, Christopher Bruner, Stephanie Dupont, and Professor Reinhold Dauskardt for insight and discussion on this topic over the years. The authors also acknowledge funding from the Office of Naval Research Award No. N00014-14-1-0580 and N00014-14-1-0280 and the King Abdullah University of Science and Technology.