Integrated Dye-Sensitized Solar Cells from Recycled Polymers for Sustainable Energy Storage

Thesis Abstract

Integrated Dye-Sensitized Solar Cells (DSSCs) crafted from recycled polymer matrices present a viable pathway to low-cost, sustainable energy storage by coupling solar harvesting with energy buffering. The study addresses the dual challenges of plastic waste management and the need for scalable, eco-friendly photovoltaic technologies that synergize energy generation with storage in a single device. The aim is to design, fabricate, and evaluate DSSCs incorporating recycled polymer substrates as flexible, lightweight charge-transport scaffolds and to assess their photovoltaic performance, stability, and practical applicability under real-world operating conditions. Specific objectives include (1) developing a recycling-grade polymer blend compatible with photoanode and counter-electrode architectures, (2) optimizing dye uptake and interfacial energetics through surface-modification strategies informed by work function tuning, (3) integrating a compatible solid or quasi-solid electrolyte to enable energy storage within the same device, (4) evaluating electrochemical and photovoltaic performance metrics across bending and thermal stress tests, and (5) performing a life-cycle and techno-economic assessment to compare environmental footprints against conventional DSSCs and Li-ion-based storage systems. The methodology adopts an experimental design with a factorial optimization framework. The population comprises recycled polymer feeds collected from municipal post-consumer streams, with sample sizes of 8 distinct polymer grades and 12 surface-modification chemistries evaluated. Materials characterization employs Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and scanning electron microscopy (SEM) to elucidate polymer compatibility with TiO2 photoanodes and dye anchoring groups. Device fabrication follows a standardized screen-printed configuration for scalable production, with 50 replicates per polymer grade to generate statistically robust performance data. Data collection instruments include impedance spectroscopy (EIS) for charge-transfer resistances, cyclic voltammetry (CV) for electrochemical stability, intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) for dynamic response, solar simulator testing under AM1.5G (1000 W/m2) conditions, and accelerated aging under 85°C/85% relative humidity. The validity and reliability of instruments are supported by calibration against NIST-traceable standards and repeated-measures reliability assessments (Cronbach’s alpha > 0.85 for any survey-like instrumentation and experimental repeatability tests with coefficient of variation <5%). Data analysis employs multiple regression to model power conversion efficiency (PCE) as a function of polymer grade, dye loading, electrolyte type, and interfacial modification; ANOVA tests compare performance across processing variants; SEM/EDS and FTIR mapping elucidate morphology–chemistry correlations; and Life Cycle Assessment (LCA) using ReCiPe methodology quantifies environmental impacts. A theoretical framework grounded in interface energetics and polymer physics incorporates the Gerischer and Marcus transfer models to interpret charge-transfer dynamics, complemented by the Donor–Acceptor theory to rationalize dye–polymer interactions. The expected findings indicate that recycled polymer scaffolds with tailored surface functionalities can achieve competitive PCEs (5–9%) with robust mechanical flexibility, enhanced stability under thermal cycling, and reduced hysteresis due to improved electrolyte solid-state compatibility. It is anticipated that solid-state or quasi-solid electrolytes integrated within the device will enable energy storage functionality without compromising charge transport, yielding stable integrated devices over 1000 hours of accelerated aging and maintaining at least 80% of initial efficiency after thermal stress. The study contributes to knowledge by demonstrating a feasible approach to valorize recycled polymers into functional, energy-harvesting and storage devices, expanding the material choices for DSSCs and advancing circular economy goals in photovoltaic technologies. The main conclusion is that recycled polymer-based DSSCs with engineered interfacial chemistries and compatible solid electrolytes can deliver sustainable energy storage with meaningful environmental and economic advantages, albeit with trade-offs in initial efficiency that are offset by gains in scalability and end-of-life circularity. Recommendations include optimizing dye–polymer coupling chemistries to maximize dye uptake per surface area, expanding the repertoire of recyclable polymer types compatible with high-bandgap dyes, standardizing accelerated aging protocols for polymer-based DSSCs, and conducting pilot-scale demonstrations in flexible, portable energy systems to validate commercial viability.