Adding quantum wells to the intrinsic region of a p-i-n solar cell improves its conversion efficiency in the following ways: 1. Quantum wells allow a wider range of photon energies to be absorbed by shifting electrons to higher energy levels. This improves the solar spectrum absorption. 2. Electron-hole pairs generated in the quantum wells have a longer lifetime, increasing the probability that they will separate and be collected before recombining. 3. The quantum wells act as intermediate energy levels, allowing photons of lower energy to still promote electrons provided the energy difference is matched by the quantum well transition. However, limitations include the solar spectrum not being truly monochromatic, so not all energies can be utilized.