Self‐Doped n‐Type Quinoidal Compounds with Good Air Stability and High Electrical Conductivity for Organic Electronics

Abstract

AbstractAir stable n‐type conductive molecules with high electrical conductivities and excellent device performance have important applications in organic electronics, but their synthesis remains challenging. Herein, we report three self‐doped n‐type conductive molecules, designated QnNs, with a closed‐shell quinoidal backbone and alkyl amino chains of different lengths. The QnNs are self‐doped by intermolecular electron transfer from the amino groups to the quinoidal backbone. This process is ascertained unambiguously by experiments and theoretical calculations. The use of a quinoidal structure effectively improves the self‐doping level, and thus increases the electrical conductivity of self‐doped n‐type conductive molecules achieved by a closed‐shell structure from<10−4 S cm−1 to>0.03 S cm−1. Furthermore, the closed‐shell quinoidal structure results in good air stability of the QnNs, with half‐lives>73 days; and Q4N shows an electrical conductivity of 0.019 S cm−1 even after exposure to air for 120 days. When applying Q6N as the cathode interlayer in organic solar cells (OSCs), an outstanding power conversion efficiency of up to 18.2 % was obtained, which represents one the best results in binary OSCs.