B ← N Coordination Enables Efficient p-Doping in a Pyrazine-Based Polymer Donor Toward Enhanced Photovoltaic Performance

Abstract

Herein, we reveal a p-doping method in an organic semiconductor through the intermolecular B ← N coordination to realize improvement of hole mobilities and the corresponding photovoltaic performance enhancement. For this purpose, we first design and synthesize a pyrazine-based polymer containing N atoms in the backbone, namely, poly­[4,8-bis­(4-chloro-5-(2-ethylhexyl)­thiophen-2-yl)­benzo­[1,2-b:4,5-b′]­dithiophene-co-3-dodecylthiophene-co-pyrazine] (PBP-Cl). Then, we realize the p-doping to PBP-Cl readily using a boron-Lewis acid dopant (tris­(pentafluorophenyl)­borane, BCF), which can form the intermolecular B ← N coordination and enhance the carrier mobilities by a factor of ca. 2.0-fold. The B ← N coordination-induced p-doping effect was further applied in PBP-Cl/Y6-based organic solar cells (OSCs) and realized an impressive device performance enhancement from 13.70 to 15.17%. This work proves an innovative and effective path toward high-performance OSCs using boron-Lewis acids to dope the nitrogen-based active layers via B ← N coordination.

Pyrazine-Based Water-Soluble Conjugated Polymer Synthesis Enabled by Synchronized Pyrazine Construction and Polymerization

“…Among nitrogen-containing heterocycles, the pyrazine ring features two imine nitrogen–carbon bonds (CN) positioned symmetrically at the 1,4-positions, contributing to its planar structure and strong electron affinity . This configuration renders it susceptible to form noncovalent bonds, such as hydrogen bonds and anion−π bonds. , Therefore, pyrazine and its fused ring derivatives have been employed for preparing high-performance conjugated polymers (CPs) by the research groups of Lei, Wang, Zhang, Li, Liu, etc., − in recent years. However, the pyrazine rings serving as building blocks to construct WSCPs have not yet been reported due to the synthetic challenge.…”

An over 16% efficiency organic solar cell enabled by a low-cost pyrazine-based polymer donor

“…32 However, there is very little research on the use of the pyrazine unit in OSCs. [32][33][34] Herein, we utilized low-cost pyrazine to design and synthesize a pair of polymers PPz and PPz-T, and investigate their differences in optical absorption, energy levels, pre-aggregation behaviours, photovoltaic performance, blend morphology, etc. Materials-only cost (MOC) analysis revealed considerably low synthesis cost for both polymers with few synthetic steps.…”