Study Of Charge Transfer In The System Of Organic Solar Cells Based On Sers Method

Since organic solar cells（OSCs）were arisen,there has been much attention.However,interface carriers dynamic problem has been interfering with the progress of OSCs.Interface charge transfer（CT）is particularly important to achieve the efficient photoelectric conversion efficiency（PCE）of photovoltaic devices.Hence,modulating the CT process poses a major challenge for OSCs and monitoring the CT dynamics demands further research.Surface-enhanced Raman scattering（SERS）technique was successfully used herein to monitor the CT process.In order to know more about the CT process in the OSCs system,this article takes the classic organic polymer:fullerene derivative materials and organic polymers:non-fullerene material heterojunction systems as the basic research objects,and uses SERS technology to monitor CT process.In addition,the process of CT controlled by ordered photocathode materials was investigated by growing heterojunction on the surface of ordered metal-metal oxide array cathode materials.The detailed content is shown as follows:（1）Monitoring the CT process in the Ag-polymer-fullerene system have been builded based on SERS technique,CT process strongly depends on the carrier density in the silver-polymer-fullerene system.However,the carrier density can be controlled by both the acceptor and donor concentrations.Changes in donor and acceptor concentrations showed opposite effects on CT between donors and acceptor.This study provides a new theoretical basis for the CT kinetic process in the metal-polymer-fullerene system.These results also indicate that the SERS technique can accurately monitor microscopic CT dynamics in metal-polymer-fullerene systems and that modulation of donor/acceptor concentration is an effective strategy for regulating CT between organic optoelectronic materials.（2）In the case of the post-annealing bulk heterojunctions（BHJ）of regioregular organic polymer and the soluble fullerene derivative,electrical properties have been studied based on the Raman spectroscopy.The study found that a well enough noteworthy phenomenon is the"return-back"shift of the Raman signal at the～1450cm^-1with annealing temperature increasing.It may be due to the CT,resulting in the significant change of resistivity（ρ）.In addition,the connection between Raman intensity andρis also established.This study is unprecedented to establish a clear connection between frequency shift and electrical properties,indicating that Raman technique opens a new avenue to analysis the electrical properties and characterize the performance of the battery.（3）The internal CT dynamic process in the non-fullerene organic solar cells（NF-OSCs）was monitored by SERS technology.Energy level difference of the BHJ was regulated by changing the concentration ratio of the non-fullerene acceptor（NFA）and the organic polymer donor,and the CT process mechanism of between different energy levels was realized.This regulation highlights the potential characteristics that OSCs can be used to develop high-performance organic photoelectric materials,thus realizing the high PCE of OSCs.（4）The PS/Ag/Al₂O₃ordered arrays as metal negative electrode were fabricated by magnetron sputtering technology.By changing the Al₂O₃sputtering time,diameter of the hollow silver shell structure was successfully adjusted,the regulation of localized surface plasmon resonance（LSPR）peak in the UV-visible-infrared region was realized,and the relationship between the change of peak displacement and the nanoparticle diameter was obtained.Y6:PM6 BHJ was grown on the PS/Ag/Al₂O₃ordered arrays,SERS intensity gradually increased due to the coupling effect of LSPR and CT.When the Ag sputtering time was 120 s,and the diameter of shell structure was 250 nm,CT efficiency was the best.The expansion of the light absorption range is not only of great value in the field of batteries,SPR sensors and SERS,but also provides a new direction for the development of new metal electrode materials.