The Research On High Performance Cadmium Telluride Nanocrystal Solar Cells By Controlling Anode Interlayer And Doping

Cd Te NC(nanocrystal) is a very promising active layer in the solution processed nanocrystal thin film solar cells because of the large molar extinction coefficient(105/cm) and the reasonable low band-gap(~1.5e V) which can match well with the sun absorption spectra. It should be pointed out that Cd Te NC solar cells with a high PCE which is currently obtained are based on the device structure of ITO/Cd Te/Zn O(or without) /Al. As the work function of Cd Te can rise as high as ～5.3e V, the contact between the ITO(work function of ITO is about 4.7e V) and the Cd Te is non-ohm, which results in a Schottky energy barrier for the hole transfer. A low Voc(less than 0.6V) and a low fill factor(below 60%) are usually obtained in this case.Here, we describe a novel method for producing a low-resistance contact to Cd Te NC by using Au, Mo Ox or C60 as the anode interlayer between the ITO and Cd Te NC active layer in the Schottky diode configuration of the ITO/Interlayer(Au, Mo Ox, C60 or without)/Cd Te NC/Al. A dramatic improvement in Voc and FF was found in the case of devices with Au interlayer. The most optimal PCE obtained in this case is as high as 5.3%. Besides, we also studied how Au interlayer with a different thickness(0nm, 0.5nm, 1nm, and 2nm) affects the device performance based on the device structure of ITO/Au/Cd Te NC/Al. An optimal thickness found in this case is 1nm with a highest PCE of 5.6%.What’s more, solar cells with diode configuration of the ITO/Cd Te NC/Zn O/Al were fabricated with sol-gel based Zn O doped with Al or In by adding different mol/mol(1%, 3%, and 5%) Al or In to the zinc acetylacetonate precursor. A dramatic improvement was obtained with a highest PCE of 9.3% by using the In: Zn O(3%) as the n-Zn O by means of a forward bias treatment before traditional measurement of J-V curve.