Organoboron-embedded functional materials: recent developments in photovoltaic and luminescence properties

Abstract

Organoboron chemistry has achieved a significant breakthrough over the past few years. As a Lewis acid, the B atom coordinated with Lewis bases such as N or O atoms formed organoboron building blocks that exhibited pronounced electron-deficient characteristics and unique optical properties such as low LUMO/HOMO energy, wide absorption ranges and multiple processing sites. The incorporation of B–N/B–O building blocks into organic small molecules or polymer backbones not only generates unique structures but also presents promising prospects for their application in various fields. Several representative B–N/B–O building blocks are reviewed in this paper and their embedded organoboron materials are investigated for organic solar cells (OSCs) or luminescence applications. The PPAB units exhibit robust near-infrared (NIR) absorption and possess a high fluorescence quantum yield, as well as exceptional thermal and photochemical stability. Additionally, the broad absorption and high molar extinction coefficient, remarkable redox properties, ease of structural modification, and excellent solubility also make BODIPY a fundamental building block in the field of photonics. The BNBP building blocks with typical coordination and covalent bond hybridization resonance also demonstrate superior photovoltaic performance and are predominantly employed as acceptor materials in the active layer. Finally, BF₂bdks exhibits strong luminescence both in solution and the solid state, characterized by tunable fluorescence emission and two-photon excited fluorescence. Detailed discussions are presented on how to finely tune the absorption spectra, energy levels, and electron mobility properties of organoboron materials through molecular design. It is noteworthy that distinct from other reviews providing a longitudinal summary of organoboron molecule synthesis, coordination structures, or single properties, we focus on organic photovoltaics simultaneously providing a horizontal overview of various applications due to the excellent luminescent properties of organoboron materials. Valuable insights into the opportunities and challenges associated with the application of organoboron materials are also provided.