Effective Ligand Passivation of Cu₂O Nanoparticles through Solid-State Treatment with Mercaptopropionic Acid

Abstract

In colloidal nanoparticle (NPs) devices, trap state densities at their surface exert a profound impact on the rate of charge carrier recombination and, consequently, on the deterioration of the device performance. Here, we report on the successful application of a ligand exchange strategy to effectively passivate the surface of cuprite (Cu2O) NPs. Cu2O NPs were prepared by means of a novel synthetic route based on flame spray pyrolysis. FTIR, XRD, XPS, and HRTEM measurements corroborate the formation of cubic cuprite Cu2O nanocrystals, excluding the possible presence of undesired CuO or Cu phases. Most importantly, steady-state emission and transient absorption assays document that surface passivation results in substantial changes in the intensity of emissive excitonic states--centered at copper and oxygen vacancies--and in the lifetime of excitons near the band edge. To shed light onto ultrafast processes in Cu2O nanocrystals additional pump probe experiments on the femtosecond and nanosecond time scales were carried out. Two discernible species were observed: on one hand, an ultrafast component (~ps) that relates to the excitons; on the other hand, a long-lived component (~μs) that originates from the defects/trap states.

A Universal Interface Layer Based on an Amine‐Functionalized Fullerene Derivative with Dual Functionality for Efficient Solution Processed Organic and Perovskite Solar Cells

“…[8][9][10] For instance, it is shown that the direction of the vertical segregation in organic bulk-heterojunction (oBHJ) can be effectively controlled by modifying the surface energy. [8][9][10] For instance, it is shown that the direction of the vertical segregation in organic bulk-heterojunction (oBHJ) can be effectively controlled by modifying the surface energy.…”

Photocurrent generation in carbon nanotube/cubic-phase HfO2 nanoparticle hybrid nanocomposites

“…Here, contrary to the previous two semiconductors, novel optical properties and photocurrent generation are expected from the hybrid material studied in under band gap excitation conditions. Nevertheless, one has to also consider that nanoparticles in contact with the CNT may undergo surface passivation along with corresponding changes in the electron trap states within the band gap [ 35 ]. Furthermore, since the CNTs are not functionalized in the present study, a direct insight into the role of intrinsic defects in the as-grown CNTs can be attained in the process of attaching nanoparticles to their surfaces.…”

Elucidating the Excited‐State Properties of CuInS2 Nanocrystals upon Phase Transformation: Quasi‐Quantum Dots Versus Bulk Behavior

“…As a consequence, the excitonic peak seen at 545 nm vanishes and the bandgap ( E g ) shifts towards the bulk value for CIS. [ 24,25 ] Second, EDX and Raman data infer that higher annealing temperatures lead to the conversion from copper-defi cient to copper-rich CIS NC fi lms. The broadness of the PL implies a rather large-size distribution, [ 21 ] which is consistent with the observation of two absorption peaks at 545 and 740 nm.…”