Intensive near-infrared emitting Au7Cu10 nanoclusters for both energy and electron harvesting

Abstract

Triplet excitons have gained increasing recognition as inherent characteristics of various nanomaterials. However, the practical application of triplet excitons is limited due to their confinement within the material where they originate, posing significant challenges to harnessing their potential. In this work, we report direct extraction of both triplet energy and electrons from newly synthesized atomically precise Au₇Cu₁₀ nanoclusters (NCs). These NCs exhibit intensive near-infrared (NIR) emission with a quantum yield of 31% at room temperature. They also display near-unity quantum yield of intersystem crossing (ISC) with strong spin–orbit coupling (SOC) up to 864 cm⁻¹. Consequently, Au₇Cu₁₀ NCs can act as triplet sensitizers, facilitating efficient triplet–triplet annihilation and achieving upconverted emission with an efficiency of 18.4% in perylene. Furthermore, rapid electron injection from Au₇Cu₁₀ NCs in the triplet state to methyl viologen was clearly observed. This study represents the first direct extraction of both triplet energy and electrons from the same metal NCs, indicating their potential as molecular triplet energy and electron surrogates in optoelectronics, photocatalysis, and solar energy conversion.