Multi-armed imide-based molecules promote interfacial charge transfer for efficient organic solar cells

Abstract

Naphthalimide-based molecules, namely NEN and NTA, were designed and utilized as versatile cathode interlayers in organic solar cells (OSCs). Compared with one-armed NA previously reported and two-armed NEN, the NTA with a three-armed molecular structure exhibits more clearly the bathochromic-shifted absorption, aligned work function, stronger self-doping effect, and higher electron mobility. The PM6:Y6-based OSCs with NTA as the cathode interlayer obtains a power conversion efficiency (PCE) of 16.86%, higher than that of NEN (PCE = 1.18%) and NA (PCE = 0.79%). Simultaneously, the PM6:Y6-based devices with NTA possess satisfactory thickness tolerance and better stability. In addition, NTA-based semitransparent devices give a maximum PCE of 13.69% with high short-circuit current density and average visible transmittance. It is demonstrated that the three-armed naphthalimide-based molecule NTA could obtain better interfacial charge transfer performance in OSCs.