Photoexcited hot electrons from conductors can be injected into the conduction bands of wide-bandgap materials, thus enabling the visible and near-infrared (NIR) photoactivities of light-harvesting devices. While metals have been dominantly used as conductors to excite hot electrons, we demonstrate that transparent conductive oxides (TCOs) can also be used for this purpose. Trilayer structures consisting of a thin dielectric layer sandwiched by TCOs show photoresponsiveness in UV, visible, as well as NIR wavelength range. As these trilayer structures are transparent, they can be used to monitor light without blocking it.