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

Abstract

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.