HyNA-LDI-MS: A Real-Time Mass Spectrometric Approach for Probing Interfacial Charge Transfer

Abstract

Understanding charge transfer at semiconductor-metal interfaces is central to advancing photoelectronic materials, yet real-time monitoring of such ultrafast processes remains elusive. Here, we introduce a hybrid nanoarray-enhanced laser desorption/ionization mass spectrometry (HyNA-LDI-MS) strategy that enables direct and rapid tracking of photoelectrons and hot carriers at hybrid interfaces. Using juglone as an electron scavenger and representative analytes as hole probes, we provide mass spectrometric evidence of interfacial charge generation and reveal markedly higher transfer efficiency at conductive interfaces compared with insulating ones. Incorporating 4-methylbenzylpyridinium as a chemical thermometer uncovers a competition between charge transfer and photothermal heating: conductive interfaces favor efficient electron transfer that suppresses heat generation, while insulating ones convert excited electrons predominantly into thermal energy. These insights, supported by complementary optoelectronic studies and density functional theory-calculations, establish HyNA-LDI-MS as a powerful tool to unravel charge-energy dynamics at complex interfaces. This study provides fundamental insights into interfacial processes, informing the design of high-performance analytical platforms such as LDI-MS systems and offering significant implications for related biomedical fields.