Nanostructured Hybrid Films for Potential Solar Cell Applications

Abstract

Solar energy is the best candidate to meet the future energy needs of renewable energy. Organic and inorganic solar cells have attracted considerable interest from researchers in the past decade. Organic and inorganic solar cells have the advantages of low cost, diversity, low-temperature treatment, and solution processability. However, organic and inorganic solar cells are still not widely available for commercial use. Due to the stability of materials and incomplete structural studies. Also, the power conversion efficiency of the cells is limited. This thesis presents an investigation of how power conversion efficiency is affected by nanostructure in organic-inorganic nanocrystal hybrid solar cells and organic metal halide perovskite solar cells. In the first study, zinc oxide nanocrystals (ZnO NCs) are used with poly[2-methoxy -5-(3,7- dimethyloctyloxy) -1,4-phenylenevinylene] (MDMO-PPV) to establish a layer-by-layer film. The morphologies, contact angle, light absorption and photoluminescence properties of the multi-layer films are investigated. A significant difference in the coverage of MDMO-PPV by the concentration of ZnO NC was observed. A highly tunable light absorption of the multi-layer film was established by UV-Visible spectroscopy. The PL spectra showed a reversible quenching and a surprising red-shift of the MDMO-PPV emission peak. A high open-circuit voltage of 0.80 V was measured in the multi-layer devices. Then, nanostructured one-step polymer template super porous (PTSP) TiO2 films and perovskite films were investigated. Poly (N-isopropylacrylamide) microgels (PNIPAM MG) are solvent-swellable and temperature-swellable, inherently colloidally stable, and have excellent film-forming properties. They were used as scaffold pre-forming template. A comparison of the optical properties and morphologies of PTSP-TiO2 layer between the well-established commercial mesoporous layer and the new combined PTSP-TiO2 was conducted. The pore size of mesoporous (meso)-TiO2 is significantly increased by adding PNIPAM MG particles. We prepared the perovskite film on different TiO2 layers. The morphologies, optoelectronic properties, and device characteristics of the perovskite layer were studied. An unexpected finding from the study was that the perovskite grain size increased with increasing PTSP-TiO2 pore size. The photoluminescence emission intensity of the perovskite/TiO2 films decreased with increased pore size of the TiO2 layer. The power conversion efficiency (PCE) of perovskite device on PTSP-TiO2 film is 20% higher than that of the control device and the champion device reached 18.8%.

Date of Award	1 Aug 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Brian Saunders (Supervisor)