Facile one-pot polymerization of a fully conjugated donor-acceptor block copolymer and its application in efficient single component polymer solar cells

Conjugated block copolymers containing donor (D) and acceptor (A) blocks have high potential for single component polymer solar cells (SC-PSCs), but still exhibit the complexity of polymer synthesis and low device efficiency. In this research, we successfully synthesized a new fully conjugated D-A block copolymer (CDABP) by performing the entire reaction in one-pot from start to completion. This polymerization method has the advantage of saving synthesis time and cost. The photoluminescence (PL) of the CDABP film was completely quenched due to photoinduced inter/intramolecular charge transfer. A single component polymer solar cell (SC-PSC) with a CDABP film annealed at 180 °C showed the maximum power conversion efficiency (PCE) of 5.28%, a high short circuit current of 10.77 mA cm^-2 and a fill factor of 62.86%, which is much higher than that (2.62%) of the device with the as-cast film. This performance can be attributed to its fine internal/surface morphology and high crystallinity of the CDABP film. In addition, transient absorption experiments on the CDABP films showed that charge carrier generation is faster and the lifetime of the generated charge carriers is longer in the annealed film than in the as-cast film. Our research explicitly provides a new structural design and simple synthesis strategy for D-A conjugate block copolymers for high-efficiency SC-PSCs.