Shelf-Life Comparison of Paper Solar Cells With Either MoO₃ or Epoxy as Encapsulation Layers

Paper substrate organic solar cells (OSC) are susceptible to degradation during ambient use and storage. An effective and low-cost encapsulation is desirable. MoO3 and UV-curing epoxy layers are compared as possible encapsulation options for P3HT:PCBM bulk heterojunction solar cells on paper substrates. Two encapsulation structures are explored–encapsulation on top of the device and top and bottom of the device. The shelf-life studies as per the widely accepted ISOS-D-1 protocol show that epoxy layers are superior to MoO3 layers as encapsulants. Most MoO3 encapsulated devices degrade below 80% of the initial efficiency values within 24 h of shelf storage, and the top and bottom encapsulation devices fare worse than top encapsulation devices. On the other hand, epoxy encapsulation allows for more than 500 h of shelf-life for the devices studied, which typically retain nearly 90% of initial efficiencies. The shelf-life stability of top and double encapsulation devices are found to be similar.