Spectrally dependent performance of hybrid colloidal quantum dots GaAs solar cells

Because of the global warming effect and energy crisis, the usage of solar energy gets more and more important in recent years. In particular, GaAs-based solar cells have been regarded as a promising candidate to provide high power conversion efficiency because of their direct band gap and strong absorption over the entire visible part of the solar spectrum. In this work, we demonstrate a hybrid design of traditional GaAs-based solar cell combined with colloidal quantum dots. Several photovoltaic parameters were enhanced, including the short circuit current density, fill factor, and power conversion efficiency, which were measured under white light illumination similar to the solar spectrum. With anti-reflective feature at long wavelength and down-conversion at high energy photons, the quantum dot effectively enhance the overall power conversion efficiency by as high as 25% compared to traditional GaAs-based device. The evolution of short-circuit current density and weighted reflectance as a function of the dilution factor of three type QDs has been investigated. The dilution factors of quantum dots solution also have been optimized for single junction GaAs devices. We also use the EQE enhancement spectrum to further distinguish between the photon down-conversion and antireflection capability of QDs. Finally, we believe this technology shall be a great candidate for next generation of highly efficient photovoltaic devices.