fig4

Figure 4. Strategies for enhancing charge separation and transfer in QDs. (A) A schematic representation of type II heterojunction; (B) Transient absorption spectra demonstrating improved charge separation by forming type II heterojunction^[63]. Reproduced with permission from ref.^[63]. Copyright 2021, John Wiley and Sons; (C) A schematic representation of Z-scheme heterojunction; (D) Photocurrent response (I-t curve) showing enhanced photocurrent by Z-scheme heterojunction engineering^[68]. Reproduced with permission from ref.^[68]. Copyright 2020, American Chemical Society; (E) A schematic representation of S-scheme heterojunction; (F) Transient absorption spectra confirming prolonged carrier lifetime by constructing S-scheme heterojunction^[69]. Reproduced with permission from ref.^[69]. Copyright 2020, Xu et al.^[69]; (G) Cu defect engineering improved charge separation in CuInS QDs, as evidenced by transient absorption spectroscopy^[64]. Reproduced with permission from ref.^[64]. Copyright 2023, American Chemical Society.