Molecular Design and Synthesis for Advanced Functional Materials: Surface Engineering of Electron Transport Layers and Dry-Developable EUV Photoresists

Abstract

This study presents the molecular design and synthesis of advanced functional materials tailored for two pivotal applications: surface-engineered electron transport layers (ETLs) in organic solar cells (OSCs) and dry-developable extreme ultraviolet (EUV) photoresists for nanofabrication. For OSCs, urea-functionalized polyethyleneimine (u-PEI) was developed to modify tin oxide (SnO₂) ETLs, addressing energy-level mismatches with Y-series nonfullerene acceptors (NFAs) and mitigating surface defects. This modification significantly enhanced SnO₂ conductivity, achieving a power conversion efficiency (PCE) of 16% and improved thermal and photostability. In nanofabrication, N-heterocyclic carbene (NHC)-based metal–ligand complexes were synthesized as sustainable, etchant-free, and dry-developable EUV photoresists. These materials demonstrated exceptional sensitivity at EUV doses as low as 8.5 mJ cm⁻² and achieved resolutions of 40 nm via wet development and 80 nm via a straightforward thermal dry development process. Mechanistic insights obtained from spectroscopic analyses revealed EUV-induced polymerization, driven by secondary electron generation and styrene chain reactions. These findings offer innovative, efficient, and sustainable solutions for OSC performance enhancement and high-resolution nanolithography, advancing the frontiers of energy and nanotechnology through strategic material design.