Three-dimensional nano-networked P3MT/PCBM solar cells.

The bulk heterojunction has been widely applied for the construction of efficient organic polymer solar cells. Typically, the heterojunction is formed as a result of the phase segregation of the donor and acceptor mixture. Here, we report a study in which, differently than the common annealing approach, efficient bulk heterojunction solar cells were fabricated using electrochemically grown 3-dimension (3D) poly-3-methyl-thiophene (P3MT) nano-networked structures. Porous and interconnected P3MT (donor) nano-structures were first electrochemically grown on a transparent Au electrode; then PCBM (acceptor) was infiltrated into the openings of the 3D P3MT nano-structure structure to form the bulk heterojunction. With this approach, efficient exciton dissociation can be realized, and importantly, excellent continuity of both donor and acceptor phases can be accomplished; and proper connection of each phase to the corresponding electrode is insured, therefore allowing effective collection of the free carriers. A power conversion efficiency (PCE) of 3.0% has been demonstrated.