Flexible polymer solar cells prepared using hard stamps for the direct transfer printing of polymer blends with self-organized interfaces

A transfer printing technique allows the development of flexible photovoltaic devices. Blending poly(ethylene glycol) (PEG) in the photoactive layer causes the PEG molecules to migrate spontaneously to and weaken the bonding at the interface between the polymer film and the Si wafer, thereby facilitating the transfer process from a hard stamp to the receiving flexible substrate. The device fabricated using this transfer printing process had characteristics similar to those of the corresponding device prepared using a spin-coating process. Using hard stamps should help to realize the low-cost, high-throughput roll-to-roll fabrication of flexible solar cells.