Luminescent, Wide-Band Gap Solar Cells with a Photovoltage up to 1.75 V through a Heterostructured Light-Absorbing Layer.

The development of photovoltaic devices with a high output voltage offers great opportunities for emerging internet of things (IoT) sensors and low-power-consumption electronics. However, the photovoltage of solar cells is yet to satisfy the requirement of driving voltage for most applications. Here, we demonstrate a wide-band gap CsPbBr-based solar cell with a heterostructured light absorber based on amino acid-modulated CsPbBr and CdSe quantum dots (QDs). Compared with the single absorbing layer device, the heterostructured device exhibits a low nonradiative recombination loss, which is strongly correlated to the high external electroluminescence of the device. In addition, in the heterostructured solar cells, carrier transfer from the perovskite to CdSe QDs induces the conduction band bending of CdSe QDs, leading to a large splitting of the quasi-Fermi levels. As a result, a remarkable photovoltage up to 1.75 V is achieved for the wide-band gap solar cells, representing an extremely low voltage deficit of 250 mV. Furthermore, the CsPbBr-based solar cells exhibit a weak light intensity dependence, showing a photovoltage of 1.59 V under room light conditions. Our work not only provides an effective approach for the design of high-photovoltage solar cells but also paves the ways of using photovoltaic devices for various applications with low driving voltage schemes.