Influence Of Luminescent Small Molecule DBP On Performance Of Perovskite Solar Cells

Organic-inorganic hybrid perovskite material,as an excellent photoelectric material,have the advantages of high mobility,bipolar transmission and high extinction coefficient,etc.The Perovskite Solar Cells?PSCs?developed on this basis have the advantages of simple preparation process,easy flexibility,and translucency.Therefore,they have received extensive attention and research in the field of solar cells in recent years.Its Power Conversion Efficiency?PCE?has rapidly increased from the original reported 3.8%in 2009 to the current23.7%,showing broad application prospects.It is shown that the interface defect state between the photosensitive layer and the charge transport layer in the perovskite solar cell is one of the main channels of energy loss.In the preparation process of perovskite solar cells,it is easy to form defects on the surface or boundary of perovskite grains,especially when the active layer comes into contact with the transport layer,which will lead to carrier recombination loss,thus limiting the efficiency and stability of devices.How to effectively extract the interface charge and improve the stability of the device by using the interface engineering to passivate the interface defects has become an important research topic in this field.To this end,this paper proposes a tetraphenyldibenzoperiflanthene?DBP?luminescent small-molecular interface passivation material,which is intercalated between the perovskite and the carrier transport layer to modify the interface and passivate surface and interface defects of perovskite,reducing carrier recombination loss,adjusting the energy level arrangement of perovskite layer and charge transport layer,enabling better transport and extraction of carriers,and achieve an effective improvement in devices efficiency by improving the light absorption of the perovskite solar cell in the near-infrared band through the energy transfer between DBP and perovskite.At the same time,the hydrophobicity of DBP is used to protect the photosensitive layer from environmental damage and improve the stability of the devices.This paper is mainly divided into two parts:?1?The role of DBP in inverted perovskite solar cells was studied.Inserting light-emitting organic small molecular material DBP as interfacial modification layer between perovskite MAPbI₃ and electron transport layer PC₆₁BM,the average PCE of PSCs reached 15.61%?the highest PCE reached 16.77%?,which was significantly higher than 14.26%of the reference devices.The reason for the increase in PCE is the result of the synergy of multiple functions of DBP.As an interface modification layer,DBP can reduce the defects of the surface and grain boundaries of the perovskite surface,thereby reducing the recombination of carriers.On the other hand,the presence of F?rster energy transfer between DBP and perovskite increases the light absorption of the MAPbI₃ layer in the near-infrared region.From the analysis of the energy level structure,the insertion of ultra-thin DBP has the effect of increasing the open circuit voltage.Moreover,the hydrophobicity and defect passivation of DBP enhance the water oxygen,heat and light stability of PSCs.?2?The role of DBP in conventional structure perovskite solar cells was studied.First,DBP was inserted as the interface layer between perovskite Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃andtheholetransportlayer Spiro-OMeTAD;Second,DBP was mixed with Spiro-OMeTAD as the dopant as the hole transport layer to study its effect on devices performance.The average PCE of PSCs based on DBP interface layer was 15.59%?the highest PCE reached 17.03%?,which was significantly higher than 14.61%of the reference devices.The average devices efficiency based on DBP as dopant is15.22%?the highest PCE is 16.67%?,which is better than that of reference batteries.For devices with DBP,Voc and FF increased,Rs decreased.The key to improve the efficiency is that DBP can improve the spectral absorption,passivate the perovskite surface and regulate the interface energy level.On the other hand,DBP's hydrophobic capacity can effectively prevent water vapor from entering the perovskite layer and improve the stability of the devices.