Post-treatment-free Carrier Transport Layers Based on Ultra-small and Ligand-free Nanoparticles Ink for Organic/Perovskite Photovoltaics

Professor Choy, Wallace Chik Ho   (Principal Investigator (PI))

Professor Hou Jianhui   (Co-Investigator)

Professor Yin Wanjian   (Co-Investigator)

36

2019-01-01

2021-12-31

700000

Post-treatment-free Carrier Transport Layers Based on Ultra-small and Ligand-free Nanoparticles Ink for Organic/Perovskite Photovoltaics

carrier transport layer, organic solar cells, perovskite solar cells, post-treatment-free, ultra-small nanoparticles

Photonics

Engineering (E)

17200518

General Research Fund (GRF)

2018

Completed

1) Understanding and realization of ultra-small and ligand-free ternary MONPs. The present synthesis method of ultra-small MONPs mainly includes the precipitation reaction for intermediates and the decomposition of the intermediates for MONPs, and no exotic ligand will be used throughout the process. We propose the new ""molecules pre-nesting mechanism"" as the NP refinement mechanism. Based on our achievements in ultra-small NiOx NPs, together with the very recent demonstration of ultra-small NiCo2O4 NPs, we aim to achieve a series of ultra-small ternary MONPs. Specifically, we will identify and establish the new mechanism through studying NP size when water is pre-nested in the intermediates. We will also adopt other pre-nesting molecules to pursue ultra-small MONPs for reinforcing the proposed mechanism. With the fundamental understanding of NP refinement, we will offer new ligand-free strategies to synthesize a series of ultra-small ternary MONPs (e.g. NiCo2O4, SrTiO3) by introducing and manipulating extra molecules in the intermediate mixtures; 2) Unveiling the mechanisms of ligand-free MONP monodispersion and its relationship with film formation from MONP inks. We will investigate the dispersity of ligand-free MONPs and unveil the mechanism of film formation with MONP inks. Specifically, we will reveal the MONPs dispersity from the viewpoint of interactions between NPs and between NP and disperse molecules. We will study the effect of varying the concentration of surface ions and functional groups on the surfaces on the dispersity status (i.e. precipitated suspension, disperse collection with mildly-aggregated NPs, and monodisperse collection). Based on the acquired results, we will gain the fundamental knowledge of the monodispersity of ligand-free MONPs and develop monodisperse MONP inks in different disperse media (e.g. water, chlorobenzene (CB), dichlorobenzene (DCB), chloroform (CF), alcohols and toluene); 3) Realizing post-treating-free MOPN CTLs for high-performance OSCs/PVSCs. In order to obtain efficient MONP CTLs, we will theoretically and experimentally optimize the band-structure, optical and electrical properties of MONPs. Meanwhile, in order to show the potential of scalability, we will achieve uniform and compact CTLs, taking the advantage of ultra-small size of the MONP inks. We will fabricate organic/perovskite solar cells using MONP CTLs to show the advantage of post-treatment-free from the ligand-free MONPs. Through the decent electrical and optical properties, good band-alignment in device, and ultra-small and post-treatment-free advantages of MONPs, we aim to improve performances of OSCs and PVSCs by the integration of MONP CTLs. ***To show our capability to manage the project, we have started to work on the project. The preliminary results of 5 nm NiCo2O4 NPs have been achieved through using a new ammonia pre-nesting strategy (see ""Research Plan and Methodology"" for details).