All‐polymer solar cells (all‐PSCs) have attracted immense attention in recent years due to their advantages of tunable absorption spectra and electronic energy levels for both donor and acceptor polymers, as well as their superior thermal and mechanical stability. The exploration of the novel n‐type conjugated polymers (CPs), especially based on aromatic diimide (ADI), plays a vital role in the further improvement of power conversion efficiency (PCE) of all‐PSCs. Here, recent progress in structure modification of ADIs including naphthalene diimide (NDI), perylene diimide (PDI), and corresponding derivatives is reviewed, and the structure–property relationships of ADI‐based CPs are revealed.

A novel A 2 −A 1 −D−A 1 −A 2 -type nonfullerene acceptor, using thiazolidine-2,4-dione (TD) as the terminal acceptor (A 2 ) for the first time, was designed and synthesized. The final molecule, BTA2, shows a high-lying lowest unoccupied molecular orbital (LUMO) of −3.38 eV and a wide optical band gap of 2.00 eV. Fullerene-free organic solar cells based on P3HT:BTA2 realized a high open-circuit voltage (V oc ) of 1.22 V with a power conversion efficiency (PCE) of 4.50%. These values are significantly higher than those of the PC 61 BM-based control device (V oc = 0.61 V, PCE = 3.67%), which indicates the feasibility of thiazolidine-2,4-dione to construct nonfullerene small-molecule acceptors with high V oc and PCE.

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