High Efficiency And Stable Polymer Solar Cells Based On AgAl Alloy Electrode

With increasing requirements of energy,sharply decreased storage of fossil fuel and environment pollution caused by burning it,the development of green sustainable energy technologies is necessary and urgent.As a next generation of Photovoltaic technology,organic solar cells(OSCs)have experienced a rapid growth in recent years,in which the power conversion efficiency(PCE)of single-junction OSCs has been over 10%and that of triple-junction has approximated 12%.Except the needed further improvement of PCE,stability of OSCs is another critical factor to meet its commercial application.So,we developed some new metal materials and well-suited modified layer to further improve the PCE and stability of OSCs.1.Considering the open circuit voltage(Voc)of Al electrode based OSCs would continue increasing up until to the maximum values,we ascribed this improvement to the existence of AlOx,which were produced by the chemical reaction between aluminum and oxygen and water.Our experiment data indicate that the formed AlOx film is very thin at the early age,which is beneficial to performance and stability of devices.Since AlOx thin film could not only modify aluminum's work function and optimize the contact quality of Al/MoO3,but also increase the built-in electric field across the whole active layer,the Voc was increased from 0.436 to 0.763 V in first five days as well as the PCE enlarged from 3.43 to 7.90%.However,the thickness of AlOx was continuously increased,the insulation characteristic of AlOx would show up and result in the accelerated degradation of conductivity and performance of OSCs.2.Introducing AgAl alloy as the anode of OSCs to enhance the performance and stability of cells.Comparing with the cells with Al or Ag anode,AgAl-based OSCs exhibit higher PCE and better stability,which is mainly attributed to the unique advantages of AgAl alloy combining both advantages of Ag and Al and inhibiting their shortcomings.On one hand,the formation of AlOx at the AgAl alloy surface can restrain the penetration of Ag atoms to the active layer and enhance cell stability;on the other hand,the thickness of AlOx film cannot be continuously increased because of the low content of Al in AgAl alloy(3%).Furthermore,AlOx can also prevent the encroachment of water from the top electrode to the active layer.3.Inserting the modified layer can perfect contact properties of the electron transport layer.LiF layer(0.7 nm)inserted between ITO and ZnO can reduce pin-hole defects in the ITO surface and minimize the dark current,improve carriers transport and collection abilities and the contact quality of ITO/ZnO.In addition,we also demonstrated that AZO film owns better electric and morphologic properties compared to ZnO film.Therefore,AZO-based cells exhibit higher short current(Jsc)and fill factor(FF).Furthermore,AZO layer compared to ZnO can improve anti-UV stability of OSCs.