Photoinduced electron transfer across the polymer-capped CsPbBr₃ interface in a polar medium

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Cesium lead bromide (CsPbBr₃) nanocrystals are promising for photocatalysis but suffer from poor colloidal stability in polar media.
• In-situ polymer capping offers a route to enhance nanocrystal stability and expand their applications.

Purpose of the Study:

• To investigate the photoinduced electron transfer properties of polymethyl acrylate (PMA)-capped CsPbBr₃ nanocrystals.
• To evaluate the impact of viologen electron acceptor structure on electron transfer dynamics and photocatalytic efficiency.

Main Methods:

• Synthesis of PMA-capped CsPbBr₃ nanocrystals.
• Probing photoinduced electron transfer using surface-bound viologen molecules with varying alkyl chain lengths.
• Determination of apparent association constants (K_app) and electron transfer kinetics.

Main Results:

• PMA-capped CsPbBr₃ exhibited a significantly higher apparent association constant (2.3 × 10⁷ M^-1) with viologen molecules compared to oleic acid/oleylamine-capped nanocrystals.
• Alkyl chain length of viologen did not affect electron transfer rate but influenced charge separation efficiency and net electron transfer quantum yield.
• Shorter alkyl chains on viologen resulted in higher charge separation efficiency (72%) versus longer chains (50%).

Conclusions:

• In-situ polymer capping of CsPbBr₃ nanocrystals with PMA effectively enhances colloidal stability in polar media, enabling their use in photocatalysis.
• The study highlights the critical role of electron acceptor structure in optimizing charge separation and quantum yield for photocatalytic applications.
• Polymer-capped CsPbBr₃ perovskite nanocrystals show potential for efficient photocatalytic reduction in polar environments.