Green Synthesis of PbS/CdS Semiconductor Nanoparticles and Its Application In Electronic Devices

Abstract

The escalating environmental concerns associated with conventional chemical synthesis methods have driven the development of eco-friendly approaches for nanomaterial fabrication. This research investigates the green synthesis of lead sulfide (PbS) and cadmium sulfide (CdS) semiconductor nanoparticles using plant-based extracts as reducing and capping agents, and evaluates their potential applications in electronic devices. PbS and CdS nanoparticles were synthesized using aqueous extracts from Azadirachta indica (neem) leaves, which served as both reducing agents and stabilizers. Characterization through UV-Visible spectroscopy revealed absorption peaks at 312 nm for CdS and 385 nm for PbS nanoparticles, confirming successful synthesis with quantum confinement effects. X-ray diffraction analysis indicated cubic crystal structures with average crystallite sizes of 4.8 nm for CdS and 6.2 nm for PbS, calculated using the Scherrer equation. Transmission electron microscopy confirmed spherical morphology with relatively narrow size distributions. Fourier-transform infrared spectroscopy identified functional groups from phytochemicals responsible for nanoparticle stabilization. The synthesized nanoparticles demonstrated promising optoelectronic properties with band gaps of 2.8 eV for CdS and 1.9 eV for PbS, making them suitable for photovoltaic and photodetector applications. Prototype solar cells fabricated using these green-synthesized nanoparticles achieved power conversion efficiencies of 3.2% for CdS-based devices and 2.7% for PbS-based devices under AM 1.5G illumination. The photodetectors exhibited responsivities of 0.42 A/W and 0.38 A/W respectively, with response times under 150 milliseconds. Compared to chemically synthesized counterparts, green-synthesized nanoparticles showed comparable performance while eliminating toxic reagents and reducing synthesis costs by approximately 40%. This study establishes green synthesis as a viable, environmentally sustainable alternative for producing semiconductor nanoparticles with functional electronic device applications.