Study Of Hole Transport Materials And Laminated Device Architecture Of Perovskite Solar Cells

In recent years,perovskite solar cells(PSCs),which utilize the organic-inorganic hybridmetal halides ABX3(A=CH3NH3+?NH(CH3)2+,B=Pb2+?Sn2+,X=I-?Br-?Cl-)as light absorbing materials,have achieved remarkable progress and aroused wide concern of the world.In a few years,the power conversion efficiency(PCE)has reached 22.1%.Hole-transport materials(HTMs)in PSCs are responsible for the extraction and transport of photogenerated holes,which play an important role in determining the optical properties of the devices.At present,2,2?,7,7?-tetrakis(N,N-di-p-methoxyphenylamine)-9,9?-spirobifluorene(Spiro-OMe T AD)has been widely used as a classical HTM in PSCs.However,the complex synthesis process and high synthesis cost of Spiro-OMe TAD severely limit the commercialization of this material.In addition,typically charge collection at the counter electrode is achieved via evaporation of a noble metal contact onto the active material in the traditional structure of PSCs.In this way,the cost is high and the energy consumption is very large.Meanwhile,the fabrication of photoanode and counter electrode on the same conductive substrate is not conducive to the flexible control of the cathode structure and performance.At the same time,once any part of them has problems,it will lead to the failure of the entire device.In this thesis,we designed and synthesized two easily prepared and low cost HTMs to replace the traditional Spiro-OMe TAD.We believe that these new materials will develop potential alternatives to expensive traditional HTMs for the fabrication of cost-effective and high-performance photovoltaic devices.Besides,we designed and fabricated a new-type laminated structure PSC where the photoanode and the counter electrode were prepared separately.Thus,the negative effects that the preparations of counter electrode might bring to the photoanode were avoided,which made a great contribution to flexibly design the preparation process.In addition,we could replace the inappropriate photoanode or counter electrode in device applications according to the need at any time.Based on this structure,the interface could be further adjusted to obtain better photovoltaic performance.Firstly,we designed and synthesized two easily prepared and low cost methoxyaniline-substituted dibenzofuran derivatives HTMs,BF-002 and BF-003.A systematic study of the two materials shows that: BF-002 and BF-003 almost exhibit no absorption in the visible region,they both have good thermal stability and high conductivity,and the two HTMs possess favorable energetics for hole transfer from perovskite into theHTM layer,indicating that they can be promising HTMs in PSCs.Then,we fabricated PSCs with the two HTMs,the devices fabricated from BF-002 and BF-003 show PCEs of 14.20%and 14.07% respectively,which are comparable to that of the Spiro-OMe TAD based cells.Moreover,the PSCs based on BF-002 and BF-003 have good reproducibility and better stability.The above results show that BF-002 and BF-003 are completely feasible in photovoltaic devices such as PSCs,which can reduce the cost of devices.Secondly,we designed a new-type laminated structure PSCs,which broke through the traditional device structure.Based on the new structure,the photoanode and the counter electrode were prepared separately.One of the electrode was FTO/compact Ti O2/mesoporous Ti O2/perovskite/Spiro-OM e TAD/PEDOT:PSS,the other electrode was PEDOT:PSS/FTO,the two electrodes were laminated together to form a complete cell.On the basis of the structure,by adding TBP and Li salt into the PEDOT:PSS,we can change the surface characteristics,the contact between the two PEDOT:PSS layers can be strengthened,so as to suppress the internal holes recombination and improve the overall performance of the device.The PSCs based on T-PEDOT:PSS(adding TBP)and TL-PEDOT:PSS(adding TBP and Li salt)achieve PCEs of 14.76% and 14.62%,respectively,while the PCE based PEDOT:PSS device is only 10.95%.In addition,the reproducibility and stability of the devices based on T-PEDOT:PSS and TL-PEDOT:PSS are also greatly improved,and it is possible to realize the flexible disassembly and assembly of the laminated structure PSCs.