Nanoscale Si-layered systems for 3rd generation photovoltaics

Solar cells based on classical Si materials have reached their photovoltaic conversion limits. However, because Si conserves its attraction for any photovoltaic application, the problem of Si performance has to be addressed in another way : is there any method that might allow Si exploitation for 3^rd generation solar cells. Is there any possible transformation of this material from the optoelectronic viewpoint. The reply is, yes, it can be done by a nanoscale engineering. The innovative idea has to answer the question of how to combine simultaneously progress in material knowledge with latest device concepts. The present multiinterface design is based on a nanoscale Si-layered system. Electron microscopy and RBS studies show that the two Si phases (amorphous and crystalline) are separated by sharp interfaces and thin c-Si transition zones with new crystalline and optoelectronic properties. Active substructures and active interfaces can be controlled by bandgap, defect and stress engineering and allow considerable extesion of existing limits. The results obtained indicate an interesting path towards a practical realization of the postulated PV improvements on modified materials.