Exclusive Electron Transport in Core@Shell PbTe@PbS Colloidal Semiconductor Nanocrystal Assemblies

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Colloidal semiconductor nanocrystals (NCs) are crucial for solution-processable electronics, photonics, and optoelectronics.
• Controlling charge carrier transport in NC assemblies is key to tailoring their electronic and optical properties.

Purpose of the Study:

• To develop a strategy for creating exclusively electron-transporting NC assemblies.
• To investigate the effect of core@shell structures on charge carrier transport properties.

Main Methods:

• Fabrication of molecularly cross-linked PbTe@PbS core@shell NC assemblies.
• Measurement of electronic transport using conventional solid-gate and electric-double-layer transistors.
• Comparison with PbTe core-only NC assemblies.

Main Results:

• Core@shell NC assemblies exhibited exclusive n-type transport, unlike the ambipolar behavior of core-only NCs.
• A type-II heterojunction formed by the PbS shell facilitated selective carrier transport.
• Holes were strongly localized within the NC core valence level, suppressing their contribution.

Conclusions:

• The PbTe@PbS core@shell NCs demonstrate significantly enhanced n-type transport.
• These NCs are suitable for applications requiring suppressed ambipolar characteristics, such as thermoelectrics and photovoltaic devices.