Colloidal Inorganic Ligand-Capped Nanocrystals: Fundamentals, Status, and Insights into Advanced Functional Nanodevices

Abstract

Colloidal nanocrystals (NCs) are intriguing building blocks for assembling various functional thin films and devices. The electronic, optoelectronic, and thermoelectric applications of solution-processed, inorganic ligand (IL)-capped colloidal NCs are especially promising as the performance of related devices can substantially outperform their organic ligand-capped counterparts. This in turn highlights the significance of preparing IL-capped NC dispersions. The replacement of initial bulky and insulating ligands capped on NCs with short and conductive inorganic ones is a critical step in solution-phase ligand exchange for preparing IL-capped NCs. Solution-phase ligand exchange is extremely appealing due to the highly concentrated NC inks with completed ligand exchange and homogeneous ligand coverage on the NC surface. In this review, the state-of-the-art of IL-capped NCs derived from solution-phase inorganic ligand exchange (SPILE) reactions are comprehensively reviewed. First, a general overview of the development and recent advancements of the synthesis of IL-capped colloidal NCs, mechanisms of SPILE, elementary reaction principles, surface chemistry, and advanced characterizations is provided. Second, a series of important factors in the SPILE process are offered, followed by an illustration of how properties of NC dispersions evolve after ILE. Third, surface modifications of perovskite NCs with use of inorganic reagents are overviewed. They are necessary because perovskite NCs cannot withstand polar solvents or undergo SPILE due to their soft ionic nature. Fourth, an overview of the research progresses in utilizing IL-capped NCs for a wide range of applications is presented, including NC synthesis, NC solid and film fabrication techniques, field effect transistors, photodetectors, photovoltaic devices, thermoelectric, and photoelectrocatalytic materials. Finally, the review concludes by outlining the remaining challenges in this field and proposing promising directions to further promote the development of IL-capped NCs in practical application in the future.

Heterostructure from PbS Quantum Dot and Carbon Nanotube Inks for High‐Efficiency Near‐Infrared Light‐Emitting Field‐Effect Transistors

“…MAPbI 3 coating provides efficient electronic passivation of PbS CQDs and photoluminescence quantum yield of PbS-MAPbI 3 inks is 20-30%, comparable with the quantum yields of CQDs capped with oleic acid before the ligand exchange. [24][25][26] The TEM image of the PbS-MAPbI 3 CQDs is shown in Figure S1 (Supporting Information).…”

Zn-doped SnS with sulfur vacancies for enhanced photocatalytic hydrogen evolution from water

“…Recently, IV-VI group metal sulfides such as SnS, SnSe, and GeS have attracted great interest due to their narrow band gap and following desirable optoelectronic properties. [20][21][22] In particular, tin(II) sulfide (SnS) has gained increasing interest because of the merits it has, such as abundant reserves, non-toxicity, biodegradable nature, and a suitable electronic band. 23 The indirect band gap of SnS is about 1.2-1.8 eV, which is close to the optimal value for solar energy.…”

The binding affinity of monoalkyl phosphinic acid ligands towards nanocrystal surfaces

“…For example, organic ligands are often exchanged with inorganic ligands for applications in devices such as field effect transistors, photodetectors, photovoltaic devices, thermoelectric, and photoelectrocatalytic materials. 12,13 However, these manipulations cannot be accomplished without understanding the ligand-NC bond. The covalent bond classification provides a framework for describing metal-ligand bonds and has also been used to describe NC-ligand bonds.…”