Our group focuses on understanding interfacial charge transfer in photodevices and photoelectrocatalysts. We found direct electron transfer transition widely exists in many heterogenous junction interfaces, including organic/metal and organic/organic interfaces. Direct electron transfer across the interfaces provides many new opportunities such as the preservation of spin states. We developed and applied transient vibrational sum frequency generation (VSFG) spectroscopy to probe the direct electron transfer at organic interfaces through the electric field induced nonlinear responses. Direct interfacial charge transfer channels could broaden the spectral range of non-fullerene organic photovoltaics (OPVs) and enable explicit control of photocharges at interfaces.