Influence Of Metal Nanostructure On The Permanence Of Perovskite Solar Cells

Energy is the key factor for development of the world.Fossil energy has been paid attention all over the world because of the pollution it brings.It is commonly approved for the usage of renewable energy and maintaining sustainable development.With the development of silicon solar cell,the first generation of solar cell,solar energy as representative of renewable energy has been studied for a long time.Solar energy has the advantage of large reserves and wide coverage.Since 2009,the report of organic-inorganic perovskite solar cell has stimulated the third generation thin film solar cell into focus.Organometallic halide perovskite materials show wide and strong absorption,high mobility and extremely long and balanced electron–hole diffusion lengths.Because of simple synthesis process and cheap cost,perovskite solar cell（PSC）makes a great progress in recent years.Power conversion efficiency（PCE）as high as 22.3% is achieved.This super speed has exceeded the other photovoltaic devices.There is a profound and lasting impact to renewable energy.Metallic nanostructures have localized surface plasmon resonance,which can reduce light scattering.For thin film photovoltaic devices this is a novel way to reduce the problem that absorption is insufficiency because of the thinner active layer.In organic solar cell,there is some work has been performed related to the introduction of metal nanostructure.Metallic nanostructures can considerably enhance performance of the device.According to the points mentioned above,we started the work utilizing metallic nanostructures into PSCs.Firstly,we successfully synthetized different nanostructures,including Au nanospheres,Au nanorods,Ag nanospheres,Ag nanocubes and Au-Ag alloys.Then,the nanosized metals were embedded into TiO₂ compact layer of the PSCs.In order to avoid direct contact with perovskite layer,a separation layer of TiO₂ was further introduced between the composite layer of nanosized metals/TiO₂ and the layer of perovskite.To our knowledge,this is the first report to systematically study the influence of metallic nanostructures on the permanence of PSCs.As localized surface plasmon resonance of metallic nanostructures depended strongly by on the structure,morphology and size of metals,so the performance of the PSCs devices with different metallic nanostructures and sizes was compared.In the light of experimental results,Au-Ag alloy had the best impact on the permanence of PSCs device.Then the concentration of Au-Ag alloy was optimized.Employing 40-nm and 20wt% Au-Ag alloys in PSC,the best PCE was obtained,to be 15.1%.40 devices with and without alloy were fabricated.The average PCE increased from 12.6% to 14.8%.The increment was about 17.5%,which was the highest improvement for the introduction of metal nanostructure into PSCs.The systemic studies indicate that the increased device performance originates from increased light harvesting due to the increased optical path length caused by the light scattering of the metallic nanostructures.This strategy demonstrates a novel way to enhance the performance of photovoltaic devices.