The Study Of Organic Photoelectric Devices Based On Nonfullerene Materials

Organic photoelectric devices based on nonfullerene materials whose impressive characteristics of easily tunable molecular energy levels,good light harvesting capability,and potentially low-cost production processes have attracted considerable attention,especially in the area of organic solar cells?OSCs?and organic photoelectric detectors?OPD?.In this paper,a polymer of poly[?2,6-?4,8-bis?5-?2-ethylhexyl?thiophen-2-yl?-benzo[1,2-b:4,5-b']dithiophene??-alt-?5,5-?1',3'-di-2-thienyl-5',7'-bis?2-ethylhexyl?be-nzo[1',2'-c:4',5'-c']dithiophene-4,8-dione??]?PBDB-T?and a nonfullerene of 3,9-bis?2-methylene-?3-?1,1-dicyanomet-hylene?-indanone??-5,5,11,11-tetrakis?4-hexylphenyl?-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene?ITIC?were adopted as the active layer to fabricate devices and their photoelectric characteristics as well as mechanism via interface modification and preparation process were studied.Firstly,the effect of different hole transport layers?HTL?on the detectivity and photovoltaic performances were investigated.The OPD of N,N'-bis-?1-naphthyl?-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine?NPB?and N,N'-diphenyl-N,N'-bis?3-methyll-phenyl?-?1,1'-biphen-yl?-4,4'-diamine?TPD?as the HTLs were fabricated respectively and the latter device's performance is much better.Its dark current density is 9.44×10^-5A/cm² and detectivity is 2.35×10¹⁰ Jones,leading to a 35.1%improvement relative to the devices without HTL.It is because that the high energy barrier between TPD and Ag electrode effectively block the injected electrons.In addition,the photovoltaic performance of OSCs using TPD as HTL reaches as high as 8.03%,resulting in a 9.8%improvement compared with the device without HTL.Enhanced power conversion efficiency?PCE?of the device is due to the high hole mobility,broad band gap and lower lowest unoccupied molecular orbital?LUMO?energy levels of TPD,making the charge transportation more efficient in the respective channels and reducing quench possibility of photoproduction excitons.Secondly,the effects of different proportion of indene-C₆₀ bisadduct?ICBA?on the PBDB-T:ITIC system were studied.The PCE of ternary blend OSCs with 20 wt%ICBA are largely boosted to 8.82%,which reach a 26.2%improvement relative to the PBDB-T:ITIC binary reference device.The result originates from the smoother film morphology with small aggregation and uniform phase separation which are conducive to reduce the charge-transfer barrier and promote the free charge transporation as well as collection.In another aspect,a good ohmic contact formed which is beneficial to keep low bimolecular recombination at the interface of the device.In summary,the use of the appropriate HTL material with low LUMO level can improve the detectivity and power conversion efficiency of devices.And doping fullerene material of ICBA in the PBDB-T:ITIC blend can also improve the efficiency of organic solar cells.This paper provides a facile way improve the performance for OPD and OSCs.