Multiband Gap Organic Solar Cells

Interlayer are essential part of tandem solar cells. To investigate interlayers various combinations of HTL and ETL materials were used. Metal electrode penetration in the thin filsm leads to the shunts an destroys the morphoslogy of the film. Initially AG electrode was tried as the top electrode while fabrication diodes (interlayer devices) but due to metal penetration into the thin films, short devices were frequently observed. As a remedy Al metal electrode was use which resulted in better resulty with the AZO based films as they are not nano particlse as in case of ZnO and have a smoother surface providing low chances of metal penetration. In case of ZnO, where the solution evaporates after thin film is laid, and nano particles are left behind, thus offering very rough surface, posses more chances of metal penetration into the ZnO film. As a result less success was achieved with the ZnO based diodes.

While AgNw have proved again and again that their presence in the interlayer provides very robust films and also protect the neighbouring layer from interpenetration of charge carriers. AgNw has also shown a significant property of establishing Ohmic contacts in the interlayer. On the other hand, OLED based normal structured devices give very good idea about the robustness of interlayers as no EL emission because of cross flow of charge carriers was observed. Where as to answer the question related to E-Field charge spouting, low temperature measurements can be performed in the future to anser the ambiguity about the processes in the inverted OLED based structures. Anothe possibility of future work can be carrying out capacitance - voltage (C-V) measurement in the similar fashion as J-V curves are measure for tandem solar cell by creating reference top and bottom subcells.