Secondary Bonds Modifying Conjugatea??Blocked Linkages of Biomassa??Derived Lignin to Form Electron Transfer 3D Networks for Efficiency Exceeding 16% Nonfullerene Organic Solar Cells

摘要： Fabricating high-efficient electron transporting interfacial layers (ETLs) with isotropic features is highly desired for all-directional electron transfer/collection from an anisotropic active layer, achieving excellent power conversion efficiency (PCEs) on nonfullerene acceptor (NFA) organic solar cells (OSCs). The complicated synthesis and cost-consumption in exploring versatile materials arouse great interest in the development of binary-doping interlayers without phase separation and flexible manipulation. Herein, for the first time, a novel cathode interfacial layer based on biomass-derived demethylated kraft lignin (DMeKL) is proposed. Features of multiple phenolic-hydroxyl (PhOH) and uniform-distributed render DMeKL to exhibit an excellent bonding capacity with amino terminal substituted perylene diiminde (PDIN), and successfully form a high-efficient isotropic electron transfer 3D network. Synchronously, secondary bonds completely modify conjugate-blocked linkages of DMeKL, significantly enhance the electron transporting performance on cross-section and vertical-sections, and repair the contact of PDIN with active layer. The DMeKL/PDIN-based 3D-network exhibits well-matched work function (WF) (–4.34 eV) with cathode (–4.30 eV) and energy level of electron acceptor (–4.11 eV). DMeKL/PDIN-based NFAs-OSC shows excellent short-circuit current density (26.61 mA cm–2) and PCE (16.02%) beyond the classic PDIN-based NFA-OSC (25.64 mA cm–2, 15.41%), which is the highest PCEs among biomaterials interlayers. The results supply a novel method to achieve high-efficient cathode interlayer for NFAs-OSCs.