[24p-F408-1~11] 9.2 Nanoparticles, Nanowires and Nanosheets

▼ [24p-F408-8] Controllable Charge Carrier Transport in Assemblies of Core@Shell Lead Chalcogenide Colloidal Nanocrystals

〇(P)Retno Miranti¹, Ricky Dwi Septianto^1,2, Maria Ibanez³, Maksym V. Kovalenko³, Yoshihiro Iwasa^1,4, Satria Z. Bisri^1,2 (1.RIKEN CEMS, 2.Tokyo Tech, 3.IST Austria, 4.Univ. Tokyo)

Keywords:core@shell, charge carrier transport, field-effect transistor

Core@shell nanocrystals (NCs) structures have been known for their exceptional optical characteristics. It can significantly reduce Auger recombination, suppress blinking, and enhance carrier multiplication. Recently, the influence of the shell on their charge carrier transport has become a critical subject to understand. In our previous report, we have successfully demonstrated the role of PbS shelling over PbTe NC core which made them exclusively electron-transporting. The energy level offset in the so-called type-II NC made the hole strongly localized within the NC. However, the important fundamental question on how the core size and shell thickness influence the charge carrier transports of their assembly remains unanswered. The understanding on the thickness-dependent is critical to provide guides for designing the desired types of core@shell (e.g. type-I, type-II, and quasi-type-II) which are important for various applications. Here, we systematically demonstrate the effect of core size and shell thickness on their respective charge carrier transport in the PbTe@PbS core@shell colloidal NCs assemblies. The assemblies of these core@shell NCs are crosslinked by short organic molecules Properties of these assemblies are measured using both conventional solid gate transistors and electric-double-layer transistors. The electronic transport measurement shows that the transport characteristic could be controlled as a function of shell thickness and core size. We observe that the transport characteristic still conserves the PbTe ambipolar characteristic for a thicker shell and transforms to an n-type characteristic for the thinner. It suggests that the alignment of the energy levels between the core and the shell are influenced by their core and shell sizes which may form a type-I, type-II, and quasi-type-II. The capabilities to tune the electronic properties benefits in the strategies to apply these systems in a wide range of electronic applications.