Colloidal Multi-Dot Nanorods.

Colloidal nanorod heterostructures consisting of multiple quantum dots within a nanorod (-DNRs, where is the number of quantum dots within a nanorod) are synthesized with alternating segments of CdSe "dot" and CdS "rod" via solution heteroepitaxy. The reaction temperature, time dependent ripening, and asymmetry of the wurtzite lattice and the resulting anisotropy of surface ligand steric hindrance are exploited to vary the morphology of the growing quantum dot segments. The alternating CdSe and CdS growth steps can be easily repeated to increment the dot number in unidirectional or bidirectional growth regimes.

Improving photovoltaic performance of light-responsive double-heterojunction nanorod light-emitting diodes.

Double heterojunction nanorods enable both electroluminescence and light harvesting capabilities within the same device structure, providing a promising platform for energy-scavenging displays and related applications. However, the efficiency of the photovoltaic mode remains modest for useful power conversion and may be challenging to improve without sacrificing performance in electroluminescence. Through a facile on-film partial ligand exchange with benzenethiol integrated into the device fabrication step, we achieve an average of more than threefold increase in power conversion efficiency while maintaining the maximum external quantum efficiency and the maximum luminance in the LED mode.

Design Principles of Colloidal Nanorod Heterostructures.

Anisotropic heterostructures of colloidal nanocrystals embed size-, shape-, and composition-dependent electronic structure within variable three-dimensional morphology, enabling intricate design of solution-processable materials with high performance and programmable functionality. The key to designing and synthesizing such complex materials lies in understanding the fundamental thermodynamic and kinetic factors that govern nanocrystal growth. In this review, nanorod heterostructures, the simplest of anisotropic nanocrystal heterostructures, are discussed with respect to their growth mechanisms.

Highly luminescent double-heterojunction nanorods.

Anisotropic shape and band structure engineered into double-heterojunction nanorods (DHNRs) can improve and impart new optical/optoelectronic capabilities in colloidal quantum dot-based devices. However, the photoluminescence quantum yield of DHNRs, which is significantly lower than the near-ideal limit recently achieved in the state-of-the-art core/shell quantum dots, remains as their main limitation. Here, we examine how the photoluminescence of CdS/CdSe/ZnSe DHNRs is affected by (1) the length of the CdS seed nanorods, (2) the rod and tip diameter dependent variations in band offset, and (3) the CdSe-like islands on the sides of DHNRs that can result as a side-product of ZnSe shell growth.

High-Performance Sub-Micrometer Channel WSe Field-Effect Transistors Prepared Using a Flood-Dike Printing Method.

Printing technology has potential to offer a cost-effective and scalable way to fabricate electronic devices based on two-dimensional (2D) transition metal dichalcogenides (TMDCs). However, limited by the registration accuracy and resolution of printing, the previously reported printed TMDC field-effect transistors (FETs) have relatively long channel lengths (13-200 μm), thus suffering low current-driving capabilities (≤0.02 μA/μm).