Improving performance in CdTe/CdSe nanocrystals solar cells by using bulk nano-heterojunctions

We have developed an ITO/ZnO/CdSe/CdTe:CdSe/CdTe/Au novel device architecture based on solution processed CdTe and CdSe nanocrystals (NCs). The introduced hybrid CdTe: CdSe layer was made by mixing different NCs in solution, which allowed for tailoring the optoelectronic properties of the nanocomposite materials. Our novel devices demonstrated more than 30% improvement in J(sc) compared with their bilayer analogue, resulting from suppressed recombination. The champion device showed a 6.25% PCE, which is a record for solution processed CdTe: CdSe p-n junction solar cells with the inverted structure. Most important of all, the devices showed extreme stability after storage for three days when maintained under ambient conditions, and less than 3% degradation was observed in PCE after 50 days of storage.