Multi junction (MJ) solar cells are one of the most promising technologies, which can achieve high conversion effectiveness from sun to electricity. Resistance loss is one of the main implicit mechanisms limiting its effectiveness under high illumination. In this paper, we study the extent to which fine tuning the different electron gaps involved in the MJ mound can reduce the adverse goods of series resistance loss on attention dependent and independent series resistance through numerical modeling. Our results show that due to the low operating current and series resistance loss, applicable band gap engineering may significantly ameliorate the conversion effectiveness when the illumination position is advanced tha 1000 suns and the series resistance value generally exceeds0.02 Ω cm2. The impact on unborn solar cells aimed at perfecting solar spectral conversion is also bandied.
Multi junction cells include a combination of semiconductor materials with different band gaps to better absorb the solar spectrum. They are usually designed to assume that there is no series resistance loss in the battery. The best combination of electron gaps leading to the highest PCE efficiency is derived from the equal efficiency curve, which provides a degree of freedom for manufacturers to choose the materials involved in multi junction stacks. However, complementary technical constraints (e.g., lattice matching between each sub cell usually needs to minimize the amount of through dislocations between different layers) may significantly limit the possible choice of materials.
It has recently been pointed out that the extent to which series resistance affects battery efficiency depends largely on the semiconductor band gap. The series resistance loss of low band gap materials seems to be higher. In fact, at a fixed light intensity, low band gap materials produce higher photocurrent because they can absorb light in a wider wavelength range. Therefore, the deterioration of their electrical properties is more serious than that of high band gap materials.
Therefore, the series resistance loss can change the optimal combination of band gaps to achieve the highest efficiency, especially at high illumination levels. If so, the series resistance loss should be considered when designing ultra-high concentration multi junction devices.