Universal linear relationship on two-step photon absorption processes in In(Ga)As quantum dot solar cells

Appropriate photo-carrier confinement in quantized levels is indispensable to achieve efficient two-step photon absorption in quantum dot intermediate band solar cells (QD-IBSCs). In this paper, host materials with varied bandgap energy were systematically investigated on In(Ga)As QDSCs. Fourier transform infrared (FTIR) photocurrent spectroscopy revealed that the IR absorption edge and the threshold temperature of two-step photon absorption processes in series of In(Ga)As QDSCs indicated a “universal linear relationship.” The threshold temperature at 295 K was predicted with the absorption edge at 0.459 eV by extrapolating the universal relationship. It proposed strategy for cell optimization to realize efficient two-step photon absorption at ambient conditions.