Plastic photodegradation naturally takes 300–500 years, and their chemical degradation typically needs additional energy or causes secondary pollution. The main components of global plastic are polymers. Hence, new technologies are urgently required for the effective decomposition of the polymers in natural environments, which lays the foundation for this study on future plastic degradation. This study synthesizes the in-situ growth of TiO2 at graphene oxide (GO) matrix to form the TiO2@GO photocatalyst, and studies its application in conjugated polymers’ photodegradation. The photodegradation process could be probed by UV-vis absorption originating from the conjugated backbone of polymers. We have found that the complete decomposition of various polymers in a natural environment by employing the photocatalyst TiO2@GO within 12 days. It is obvious that the TiO2@GO shows a higher photocatalyst activity than the TiO2, due to the higher crystallinity morphology and smaller size of TiO2, and the faster transmission of photogenerated electrons from TiO2 to GO. The stronger fluorescence (FL) intensity of TiO2@GO compared to TiO2 at the terephthalic acid aqueous solution indicates that more hydroxyl radicals (•OH) are produced for TiO2@GO. This further confirms that the GO could effectively decrease the generation of recombination centers, enhance the separation efficiency of photoinduced electrons and holes, and increase the photocatalytic activity of TiO2@GO. This work establishes the underlying basic mechanism of polymers photodegradation, which might open new avenues for simultaneously addressing the white pollution crisis in a natural environment.

Poly(6‐(4,7‐dimethyl‐2H‐benzo[d][1,2,3]triazol‐2‐yl)‐N,N,N‐trimethylhexan‐1 aminium iodide) (PBTz‐TMAI) and poly(sodium 4‐(4,7‐dimethyl‐2H‐benzo[d] [1,2,3]triazol‐2‐yl)butane‐1‐sulfonate) (PBTz‐SO3Na) based on the same benzotriazole‐conjugated backbone but with ammonium and sulfonated side chains are designed and synthesized through side‐chain functionalization and Yamamoto polymerization, respectively, and are used as the cathode interlayers in fullerene‐ and non‐fullerene‐based polymer solar cells. The interfacial modification of PBTz‐TMAI and PBTz‐SO3Na onto the active layer achieves good energy alignment at cathode electrodes and optimized exciton‐dissociation efficiency from the active layer. Consequently, the power conversion efficiencies (PCEs) of 7.8% and 9.6% are obtained for the fullerene PTB7:PC71BM‐based and non‐fullerene PBDB‐T:ITIC‐based polymer solar cells (PSCs) with PBTz‐SO3Na interlayer. The PCS devices based on PTB7:PC71BM and PBDB‐T:ITIC active layers with PBTz‐TMAI interlayer achieved a remarkably improved performance with PCEs of 8.2% and 10.2%, respectively.

The poor energy conversion efficiency for those polymer solar cells (PSCs) creates an obstacle for their commercialization. Inspired by this issue, two cathode interlayers, PBTBTz‐TMAI and PBTzPh‐TMAI based on benzothiadiazole (BT) and benzotriazole (BTz)‐conjugated or benzene (Ph) and BTz‐conjugated alternating units (both exhibits the same tetravalent amine‐end side chain), were synthesized via Suzuki coupling polymerization and trivalent amine‐end ionization. When PBTBTz‐TMAI and PBTzPh‐TMAI were utilized as cathode interlayers in PSCs, the charge‐carrier transfer from active layer to cathode electrode was significantly improved, accompanied by an optimized exciton dissociation efficiency, primarily attributed to the introduction of tetravalent amine groups. Consequently, the device with PBTBTz‐TMAI exhibited power conversion efficiencies (PCEs) = 8.3 and 10.5% for the PTB7:PC71BM‐based and PBDB‐T:ITIC‐based PSCs, respectively. In parallel, devices with a PBTzPh‐TMAI cathode interlayer (that were established on the active layers of PTB7:PC71BM and PBDB‐T:ITIC) obtained a remarkably superior optoelectric efficiency with PCEs = 8.5 and 10.8%. These findings offer an alternative tactic toward to high efficiency PSCs to meet the increasing energy crisis.