A photovoltaic effect with external quantum efficiency above 100%: A support to the explanation for the non-traditional technique raising efficiencies for all kinds of solar cells

A V-shaped module (VSM) photovoltaic technique, which breaks traditional concepts, has been proven by European and American scientists to enable power-conversion-efficiency (η) to increase by 50% for thin-film solar cells. Such large increases in η mean that some factors besides the reflection cause η improvement. Mysterious dark energy is thought to result in the VSM effect. Furthermore, the VSM technique raises η for all kinds of solar cells (J. Environ. Sci. Eng. A 12, 214 (2023). https://doi.org/10.17265/2162-5298/2023.06.002). In this study, the external quantum efficiency (EQE) of commercially available multicrystalline silicon solar cells in the VSM was investigated, which exhibits a surprising phenomenon of EQE above 100%. For a solar cell under the condition of steady state for equilibrium, the incident energy entering the cell must be exactly equal to the total energy output from the cell. Some of light energy into the cell is thereby converted into the energy of the photoexcited electrons flowing out of the solar cell. The surplus energy is released from the cell, mainly as infrared emission, under the constraint of energy conservation. For the VSM structure, two solar cells are just placed at an angle to each other. In the VSM, infrared photons emitted from each cell could subsequently be absorbed via the defect energy levels to create additional carriers in the facing cell, resulting in the creation of more than one electron-hole pair from one absorbed photon. The EQE values exceeding 100% achieved in this study are thus explainable. The energy of infrared photons emitted from each cell is considered as the so-called dark energy. The factor of infrared photon recycling is proposed to mainly contribute to the VSM effect (arXiv:2409.20066. https://arxiv.org/abs/2409.20066). The easy-to-reproduce VSM approach opens up new avenues to study photovoltaic physics.