Our research group in Micro and Nanotechnologies focuses its activity on the manufacture of solar cells totally finished. In recent years, the group has specialized in crystalline silicon cells, with front and back electrodes, manufactured using standard emitter technology (using doping atoms diffused at high temperature, or using doped amorphous silicon layers deposited by PECVD, or using dopants introduced by laser through dielectric layers). A more recent activity is the manufacture of crystalline silicon cells with IBCs (Interdigitated Back Contact Solar cells) structure, with contacts located at the back side, leaving the front side free. With IBCs solar cells the group obtained an efficiency of 22%. Moreover, over a period of time the group was engaged in the manufacture of organic solar cells from the p-i-n structure using organic semiconductors. The principle of operation of organic solar cells are based on assuming the presence of an absorber semiconductor intercalated between two selective contacts, one allowing electron transport and blocking holes (Electron Transport Layer ETL) and another allowing hole transport and blocking electrons (Hole Transport layer HTL). The scientific experience gained in organic devices research allowed the group to design a new type of crystalline silicon solar cells. This type of solar cell combines crystalline silicon, as the absorber semiconductor, with ETL and HTL layers commonly used in organic cells. The group pioneered the use of transition metal oxide layers (in particular vanadium oxide) as HTL in crystalline silicon. The results were excellent (resulting in highly cited articles). Subsequently, the group started the fabrication of IBCs using HTLs as a hole selective layer and standard materials (such as n-type hydrogenated amorphous silicon) as electron collectors. This project deals with the manufacture of IBCs using hole and electron transport layers deposited at low temperature (less than 250 C). The layers to be used as HTLs will be Transition Metal Oxides, in particular V2O5 and MoO3 (deposited by thermal evaporation and Atomic Layer Deposition ALD) and TiO2 (ALD) as ETLs. Achieving high-efficiency crystalline silicon solar cells at temperatures below 250C is by itself an important technological goal. In this project we want to go a step further. We want to manufacture tandem solar cells. These tandem solar cells will combine silicon cells manufactured at low temperature with Kesterite solar cells, opening up the possibility of making cells (in tandem configuration) with efficiencies higher than 25%.
Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016
Programa Estatal de I+D+i Orientada a los Retos de la Sociedad