inorganic hybrid tandem solar cells attract a considerable amount of attention due to their potential for realizing high efficiency photovoltaic devices at a low cost. Here, highly efficient triple-junction (TJ) hybrid tandem solar cells consisting of a double-junction (DJ) amorphous silicon (a-Si) cell and an organic photovoltaic (OPV) rear cell were developed. In order to design the TJ device in a logical manner, a simulation was carried out based on optical absorption and internal quantum efficiency. In the TJ architecture, the high-energy photons were utilized in a more efficient way than in the previously reported a-Si/OPV DJ devices, leading to a significant improvement in the overall efficiency by means of a voltage gain. The interface engineering such as tin-doped In 2 O 3 deposition as an interlayer and its UV-ozone treatment resulted in the further improvement in the performance of the TJ solar cells. As a result, a power conversion efficiency of 7.81% was achieved with an open-circuit voltage of 2.35 V. The wavelength-resolved absorption profile provides deeper insight into the detailed optical response of the TJ hybrid solar cells. T here have been many challenging studies of thin-film solar cells as part of the effort to advance renewable energy technologies 1–3 . The main objectives of the research on next-generation photovoltaic (PV) cells, as alternatives to the currently available crystalline silicon PV systems, are to realize low-cost production as well as to enhance the power conversion efficiency (PCE). The tandem cell architecture, in which multiple solar cells with different bandgaps are stacked in series, is a promising strategy to alleviate the innate energy losses of single-junction (SJ) solar cells, i.e., the thermalization loss of high-energy photons and the transmission loss of low-energy photons 4–9