Date on Master's Thesis/Doctoral Dissertation

8-2021

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Mechanical Engineering

Degree Program

Mechanical Engineering, PhD

Committee Chair

Kate, Kunal

Committee Co-Chair (if applicable)

Druffel, Theodore

Committee Member

Bikram, Bhatia

Committee Member

Popa, Dan

Author's Keywords

Perovskite solar cell; rapid thermal annealing; intense pulse light (IPL); thin film solar cell

Abstract

Perovskite solar cells (PSCs) have garnered a great attention due to their rapid efficiency improvement using cheap and solution processable materials that can be adapted for scalable high-speed automated manufacturing. Thin film perovskite photovoltaics (PVs) are typically fabricated in an inert environment, such as nitrogen glovebox, through a set of deposition and annealing steps, each playing a significant role on the power conversion efficiency (PCE), reproducibility, and stability of devices. However, atmospheric processing of PSCs would achieve lucrative commercialization. Therefore, it is necessary to utilize materials and methods that enable successful fabrication of efficient PSCs in the ambient environment. The lab scale experiments have been dominated using deposition methods, such as spin-coating or thermal evaporation in vacuum, which are not adaptable for automation; hence, taking advantage of scalable deposition methods, such as inkjet printing, is necessary for automation. Besides deposition, post process annealing is a pivotal aspect which crystallizes the thin film materials and determines the performance and stability of PSCs. Therefore, it is necessary to further investigate this step and develop new methods and utilize potential materials vi that are amenable for scalable, high-throughput, and cost-effective automated manufacturing of PSCs. Conventional methods have successfully resulted in efficient labscale PSCs using prolong and high temperature annealing; however, industrialization requires rapid annealing methods that allow for scalable, high-speed, and cost-effective manufacturing of efficient PSCs in the ambient environment. Intense pulse light is a rapid annealing method (IPL) that allows for the lucrative, scalable, and high throughput atmospheric processing of PSCs; thus, it is necessary to study the photothermal impact on the morphology and phase evolution of the thin film materials and develop ambient processable precursors that yield efficient perovskite modules. IPL exerts intermittent millisecond(s) duration flashes carrying energetic photons to anneal the material, and the parameters of flash energy, duration, count, and interval time between flashes determine the annealing extent and affect the PV performance of PSCs. This dissertation investigates the impact of these parameters on the morphology, phase change, and conductivity of the potential PSC thin films using various material characterization techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL), impedance spectroscopy (IS), X-ray photoelectron spectroscopy (XPS), UV-Vis, as well as voltammetry, by introducing a novel additive and annealing approaches which allow for rapid fabrication of PSCs, and is applicable for rapid, cost-effective, and scalable automated fabrication of PSCs.

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