A novel p–i–n solar cell structure with i-region composed by nanocrystalline silicon (nc-Si) is introduced to study the photocurrent behavior and the quantum efficiency. By employing a theoretical model, which takes the resonant tunneling (RT) effect into consideration for nc-Si region, the current contributed from p-, i-, and n-region are calculated. The short-circuit photocurrent dependency on the structure parameters such as the width as well as the doping concentration of p-region is investigated. Furthermore, the internal quantum efficiency is simulated. Compared with the traditional solar cell, higher quantum efficiency of our cell structure is clearly demonstrated and explained especially for high-energy photon, which reveals that the RT plays a key role in improving the quantum efficiency.