Semiconductor nanocrystals (NCs) are promising materials for applications in photovoltaic (PV) structures that could benefit from size-controlled tunability of absorption spectra, the ease of realization of various tandem architectures, and perhaps, increased conversion efficiency in the
ultraviolet through carrier multiplication. The first practical step toward utilization of the unique properties of NCs in PV technologies could be through their integration into traditional
silicon-based solar cells. Here, we demonstrate an example of such
hybrid PV structures that combine colloidal NCs with
amorphous silicon. In these structures, NCs and
silicon are electronically coupled, and the regime of this
coupling can be tuned by altering the alignment of NC states with regard to
silicon band edges. For example, using wide-gap CdSe NCs we demonstrate a photoresponse which is exclusively due to the NCs. On the other hand, in devices comprising narrow-gap PbS NCs, both the NCs and silicon contribute to
photocurrent, which results in PV response extending from the visible to the near-
infrared. This work demonstrates the feasibility of
hybrid PV devices that combine advantages of mature silicon fabrication technologies with the unique
electronic properties of
semiconductor NCs.