High Efficiency and Stable Flexible Organic Solar Cells Facilitated by Light Sensitive Hydrophilic-to-Hydrophobic Converting Surface Modification of the Flexible Barrier Films.

Abstract

With the advantages of high efficiency and flexibility, the flexible organic solar cells (FOSCs) showed great application in wearable electronics. However, degradation of device performance due to the infiltration of water and oxygen into the flexible substrate becomes the main obstacle to its development. The traditional encapsulation with a sandwich structure would reduce the optical and mechanical properties of the devices and increase the device's weight. In this work, a strategy of in situ fabrication of highly efficient and long-term stable FOSCs on the highly transparent barrier film (BF) substrates is developed. A kind of light-sensitive material, o-nitrobenzyl alcohol derivatives, which can convert from hydrophilic to hydrophobic, is induced to improve the wettability of AgNWs on the substrate and enable the printing fabrication of a uniform AgNWs transparent electrode. After light conversion, the NBE films are converted to hydrophobic, which sufficiently improved the barrier property. The efficiency of the BF/NBE devices reached 16.33% and retained 80% of its initial value after being stored in the air for 600 h, which is compared to the grid devices with the glass substrate. Besides, due to the superior mechanical properties and thin thickness, the in situ FOSCs with barrier substrates exhibited excellent mechanical bending durability.