Shear-Enhanced Transfer Printing of Conducting Polymer Thin Films

Polymer
conductors that are solution-processable provide an opportunity
to realize low-cost organic electronics. However, coating sequential
layers can be hindered by poor surface wetting or dissolution of underlying
layers. This has led to the use of transfer printing where solid film
inks are transferred from a donor substrate to partially fabricated
devices using a stamp. This approach typically requires favorable
adhesion differences between the stamp, ink, and receiving substrate.
Here, we present a shear-assisted organic printing (SHARP) technique
that employs a shear load on a post-less polydimethylsiloxane (PDMS)
elastomer stamp to print large-area polymer films that can overcome
large unfavorable adhesion differences between the stamp and receiving
substrate. We explore the limits of this process by transfer printing
poly­(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)
films with varied formulation that tune the adhesive fracture energy.
Using this platform, we show that the SHARP process is able to overcome
a 10-fold unfavorable adhesion differential without the use of a patterned
PDMS stamp, enabling large-area printing. The SHARP approach is then
used to print PEDOT:PSS films in the fabrication of high-performance
semitransparent organic solar cells.