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Developing next generation, non-toxic, inorganic materials for photovoltaics and thin-film transistors https://doi.org/10.17863/CAM.101974 Huq, Tahmida Driscoll, Judith The focus of this thesis is on developing two next-generation inorganic materials for thin-film device applications, namely photovoltaics and thin-film transistors. Both of these device applications are crucial in today’s technology-based society with photovoltaics enabling sustainable generation of electricity whilst advancements in thin-film transistors allow for development of low-power, efficient electronic devices. BiOI, a non-toxic, perovskite-inspired material is investigated for photovoltaics (PVs) whilst Cu₂O, with a reasonably high predicted hole mobility is developed for *p*-type thin-film transistors (TFTs). These novel materials are fabricated with scalable processing techniques which enable lower manufacturing costs and improve energy efficiency. In the first results chapter, the suitability of non-toxic BiOI as a photovoltaic material is investigated. Dense BiOI films grown by thermal chemical vapour deposition (CVD) incorporated into an all-inorganic ITO/NiO_*x*/BiOI/ZnO/Al stack demonstrate high external quantum efficiencies (80% at 450 nm wavelength). However, the 1.9 eV band gap of BiOI is not matched to terrestrial solar spectra; the PVs achieve 1.8% power conversion efficiency. Owing to improved spectral matching with indoor light spectra, BiOI devices improve in efficiency to 4.37% under 1000 lux white light emitting diode indoor illumination, and millimetre-area BiOI devices are sufficient to power novel carbon nanotube inverters. The factor limiting further efficiency gains is downwards band-bending at the BiOI/NiO_*x* interface owing to NiO_*x* having a lower work function. In the second chapter, MoS₂ is investigated as an alternative to NiO_*x* where the work function of MoS₂ is tuned through oxygen plasma treatment to increase its work function. The experimental examination of defect tolerance of BiOI is conducted in chapter three. BiOI films are vacuum-annealed to induce surface composition changes. Large changes in surface atomic fractions (reduction in iodine and bismuth by 40% and 5% respectively, and increase in oxygen by >45%) are observed. These significant changes do not affect the electronic and optoelectronic properties, in contrast to traditional covalent semiconductors. The applicability of low-temperature (≤ 200 °C) atmospheric pressure spatial atomic layer deposited (AP-SALD) Cu₂O for use in *p*-type TFTs is explored in chapter four. The performance of AP-SALD Cu₂O is comparable to atomic layer deposition (ALD) grown Cu₂O with an I_*ON*/I_*OFF* ratio of 10³, and field-effect mobility between 10^-4 - 10^-3 cm²·V^-1·s^-1, illustrating the potential of AP-SALD grown films for integration with flexible substrates. University of Cambridge 2023-03-05 Thesis Doctoral Doctor of Philosophy (PhD) eng PragmatIC Aziz Foundation https://www.repository.cam.ac.uk/handle/1810/358203 https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/045aaa8d-1fb4-4f56-a2ad-2d5dce763141/download c3db284408ce62b62b48c91b7e89c2cc https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/775cc775-d4be-4642-aeaa-495ed37c0e86/download 87eda9de84448d1f82354d60eee3eb5f http://purl.org/NET/rdflicense/allrightsreserved atmospheric pressure spatial atomic layer deposition bismuth oxyiodide copper oxide indoor photovoltaics nanotechnology perovskite-inspired materials photovoltaics thin-film transistors