Narrow electroluminescence linewidths for reduced nonradiative recombination in organic solar cells and near-infrared light-emitting diodes

Abstract

<h2>Summary</h2> The minimization of nonradiative recombination losses is essential to transcend the efficiency of state-of-the-art organic solar cells (OSCs) and near-infrared (NIR) organic light-emitting diodes (OLEDs). Indeed, reduced nonradiative processes will result in high electroluminescence (EL), external quantum efficiency (EQE_EL), and low nonradiative voltage losses (Δ<i>V</i>_OC,nr) for OSCs. Here, we study the EL properties of a set of polymer-small molecule blends and find a relationship between the EL emission linewidth, EQE_EL, and Δ<i>V</i>_OC,nr. Based on these findings, we reduce Δ<i>V</i>_OC,nr from the typical values around 250 mV down to an unprecedented value of 155 mV using a blend comprising a low-molecular-weight PM6 polymer donor and a highly emissive nonfullerene acceptor (Y16F). Importantly, the PM6:Y16F blend yields an EQE_EL (0.52%) among the best reported fluorescent NIR-OLEDs in the 900-nm range. These findings clearly indicate the existence of organic material blends that combine both excellent photovoltaic and electroluminescent properties.