A n-type conjugated polymer containing naphthalene diimide (NDI) and 1,3,4-thiadiazole (TZ) moieties, named PNTZ, has been synthesized and applied for all-polymer solar cells (all-PSCs). By the incorporation of TZ unit into the polymer main chains, the lowest unoccupied molecular orbital level of this polymer has been adjusted effectively. In addition, the electron-acceptor PNTZ shows a broad absorption spectrum in the range of 300-700 nm, and possesses complementary absorption spectrum with the electron-donor PTB7-Th. On the basis of PNTZ as the acceptor and PTB7-Th as the donor, the all-PSCs are fabricated. After optimization, the well blend morphologies with a continuous D/A interpenetrating network are observed and the best all-PSC device exhibits a power conversion efficiency of 4.35% with a high short-circuit current density of 13.26 mA cm(-2). This research demonstrates that the TZ-containing polymer PNTZ is a promising non-fullerene acceptor for high efficiency all-PSCs. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 990-996