| dc.description.abstract | Monitoring pollution levels and extent is crucial for preserving our environment's sustainability. Advances in the technology sector, facilitated by new materials and methods, have significantly improved. Nonetheless, these advancements have increased electronic waste (e-waste), posing a significant environmental risk. Mishandling and improper disposal of e-waste can lead to the release of harmful metals and organic substances into soil and water, which poses a serious threat to ecosystems. This thesis delineates the various sources of e-waste and the current state of remediation, focusing on encapsulation, sensing, and the development of biodegradable alternatives. It specifically addresses two primary sources of electronic waste: lead-perovskite solar cells and plastic substrates used in packaging and PCB (Printed Circuit Board) applications as electronic substrates.
The renewable energy sector's extensive use of solar cells, particularly perovskites, has propelled forward the search for new materials. Lead-containing perovskite solar cells have been shown to increase photovoltaic power conversion efficiency significantly. Despite the exploration of lead-free alternatives, current research suggests that the most efficient and dependable perovskite solar cells (PSCs) utilize lead salts, which are harmful to both human health and the environment. This research integrates encapsulation modifications and sensing technologies to address lead leaching from perovskite solar cells effectively. Encapsulation involves the physical containment of a device within a polymer film and glass to improve the device’s lifetime. It was proven that modification of the encapsulant and encapsulation methods could prevent the lead from leaching into the environment. Surlyn film modified with functional groups that interact with mobile lead ions is used to encapsulate perovskite films. The functionalization of the encapsulant was tailored by modifying the matrix polymer with Zeolitic imidazolium framework- 67 (ZIF-67) through polydopamine as the anchoring platform. This effectively explored the use of surlyn beyond traditional use in photovoltaic packaging. This method leverages the affinity of lead for amine-functionalized molecules for both sensing and encapsulation purposes and exhibited a remarkable reduction in lead leakage.
It was shown that lead can leach into the environment upon degradation. Hence real-time detection and quantification are of great importance. Encapsulation using ZIF- 67 modified polymer was proven to be the effective capturing of lead ions. ZIF-67 was appropriately functionalized with aminopropyltrimethoxy silane. This was mixed with carbon paste and fabricated electrode which can effectively detect lead ions leached from degraded perovskite solar cells. A biomimicking approach was taken, where the imidazolium moiety of ZIF- 67 is structurally like amino acid Histidine, which has exhibited affinity towards lead ions. Additionally, the aminopropyl pendant group present freely interacts with lead ions. The detection limit was calculated to be 60 ppb. This sensor exhibited remarkable sensitivity in detecting lead ions in water samples, proving its efficacy in practical applications. Additionally, the ZIF- N modified carbon paste electrode was shown simultaneous detection for Pb+2 and Hg+2.
Another focal point of this thesis is the development of flexible cellulose films and composites for packaging, and electronic substrates applications. Cellulose extracted from sugarcane bagasse was crosslinked to create a biodegradable film with a water vapor transmission rate of 350 g/m²/day, suitable for both packaging and device substrates. To further reduce the WVTR, CVD-grown graphene was transferred onto cellulose by solvent casting on graphene/ copper film. Which exhibited a WVTR of 37 g/m²/day. Further biodegradability of the lab-fabricated films was assessed with composting and plant growth studies.
Additionally, an innovative approach involved replacing conventional plastic PCB substrates with those reinforced with biodegradable components. Green PCBs are an emerging field of research since the PCBs present in electronic waste are found to significantly contribute to e-waste. In this work, Microcrystalline cellulose (MCC) was functionalized with Aminopropyl triethoxy silane (APTES). The silane functionalized epoxy (SMC) was mixed with epoxy, yielding SMC- epoxy composite. Mechanical properties, dielectric constant, and thermal stability were evaluated to check the comparability with conventional PCB substrates. The degradability studies were continuing. The patterning ability was tested through the electrodeposition of copper onto the SMC-epoxy substrate. The prime focus of this work was to reduce the non-degradable hazardous plastic components in conventional PCBs up to 25 wt % of the total PCB waste. Thus, mitigating the environmental impact due to the piling up of PCB waste. | en_US |
