Size-Dependent Electrical Transport in CdSe Nanocrystal Thin Films

作者：Kang Moon Sung; Sahu Ayaskanta; Norris David J^*; Fri**ie C Daniel

来源：Nano Letters, 2010, 10(9): 3727-3732.

DOI：10.1021/nl102356x

• CdSe nanocrystals
• electrical transport
• size dependence
• thin-film transistors
• ion-gel gate dielectric

Electrical transport in films of CdSe nanocrystals with diameters varying from 2.9 to 5.1 nm was examined over 233-300 K by employing electrolyte gating to control the electron density. The transport parameters varied strongly and systematically with nanocrystal diameter. First, a strong correlation was observed between the device turn-on voltage and the size-dependent position of the lowest unoccupied electronic states of the nanocrystals. Second, the electron mobility increased with increasing particle diameter and reached a high value of 0.6 cm(2)/(V s) for films with 5.1 nm nanocrystals. Third, the charge transport could be described in terms of the nearest-neighbor-hopping mechanism with a size-dependent activation energy and a pre-exponential factor for mobility. The activation energy can be viewed as a size-dependent charging energy of an individual nanocrystal. Collectively, the combination of size and temperature-dependent measurements provides a powerful approach to understanding electrical transport in nanocrystal films.

• 出版日期2010-9