(D)n–σ–(A)m type partially conjugated block copolymer and its performance in single-component polymer solar cells.

We synthesized two types of novel poly(3-alkylthiophene)-free (D)_n-b-(A)_m conjugated block copolymers: PTQI-block-PNDISs. PTQI-b-PNDIS is the fully conjugated block copolymer, in which the donor block is connected to the acceptor block via a π-conjugated unit. In addition, the donor block was connected to an acceptor block through a non-conjugated alkylene spacer, yielding PTQI-b-PNDISL, which is a partially conjugated block copolymer. The power conversion efficiency (PCE) was 1.54% with an open-circuit voltage of 0.79 V in the single-component polymer solar cell (PSC) based on PTQI-b-PNDISL, better performance than that of the PSC containing PTQI-b-PNDIS (PCE ∼ 0.36%). These results reveal the potential for improving the photovoltaic performance in PSCs by controlling the internal morphology with exploitation of the self-segregating behavior of p- and n-blocks in the film state. [ABSTRACT FROM AUTHOR]