1) the nitroxide radicals are properly attached to the radical chain (continuous wave EPR) and 2) the polymer chain has very rigid conformations leading to a set of well-defined distances between first neighboring pairs of nitroxides (pulsed EPR). The redox group combined with the electroactive polymer showed not only a very high electrochemical reversibility but also a perfect match of redox potentials
为了减少基于聚氧化二氮的电极通常所需的导电添加剂的量,将稳定的自由基(TEMPO)与由2,7-双噻吩咔唑(2,7-BTC)组成的导电共聚物主链结合使用本征电子电导率。这项工作涉及由氧化还原氮氧化物官能化的这种新聚合物的合成。使用电子顺磁共振(EPR)技术进行的精细结构表征证明:1)氮氧化物自由基正确连接至自由基链(连续波EPR),并且2)聚合物链具有非常刚性的构象,从而导致了一组明确定义的距离在第一对相邻的氮氧化物之间(脉冲EPR)。与电活性聚合物结合的氧化还原基团不仅显示出非常高的电化学可逆性,而且还显示了双噻吩咔唑主链的去掺杂/掺杂反应与硝基自由基的氧化还原活性之间的氧化还原电位的完美匹配。这种新的有机电极显示出稳定的容量(约60 mAh g-1),并且由于导电聚合物骨架的缘故,可以大大减少碳添加剂的量。
Photo-induced charge transfer and nonlinear absorption in dyads composed of a two-photon-absorbing donor and a perylene diimide acceptor
作者:Chun Huang、Matthew M. Sartin、Nisan Siegel、Matteo Cozzuol、Yadong Zhang、Joel M. Hales、Stephen Barlow、Joseph W. Perry、Seth R. Marder
DOI:10.1039/c1jm12566d
日期:——
This paper reports the synthesis and electrochemical and optical properties of two molecular dyads (Dyad 1 and Dyad 2) consisting of a 2,7-bis(4-(diarylamino)styryl)carbazole two-photon-absorbing donor chromophore, connected by different linkers to a perylene diimide (PDI) acceptor. The photo-induced charge transfer in these compounds is characterised using transient absorption measurements. The use of the compounds for optical limiting is discussed; because of spectral overlap between the donor two-photon absorption band and the one-photon absorption band of the PDI radical anion, the dyads exhibit enhanced nonlinear absorption at wavelengths between 700 and 800 nm relative to that seen for the two-photon absorbing donor chromophore. The stronger nonlinear absorption observed for Dyad 1vs.Dyad 2 is attributed to a higher yield of photo-generated radical ions and a longer lived charge-separated state, resulting from differences in the linker between the donor and acceptor.
Conjugated polyelectrolytes and neutral polymers with poly(2,7‐carbazole) backbone: Synthesis, characterization, and photovoltaic application
作者:Xiaofeng Xu、Wanzhu Cai、Junwu Chen、Yong Cao
DOI:10.1002/pola.24547
日期:2011.3
Poly(2,7‐carbazole) neutralpolymers (PC‐N, PC‐NOH, and PC‐P) and polyelectrolytes (PC‐NBr and PC‐SO3Na) with hydrophilic pendant groups of ammonium, phosphonate, and sulfonate were synthesized as interlayers for cathode modifications in bulk‐heterojunction photovoltaic cells (BHJ PVCs). The absorptions of the polymers were determined by the poly(2,7‐carbazole) backbone, showing absorption peaks at
Synthesis and characterization of donor-bridge-acceptor alternating copolymers containing perylene diimide units and their application to photovoltaic cells
copolymers featuring coplanar cyclopentadithiophene and hole‐transporting carbazole units. We observed quenching in the photoluminescence spectra of our polymers after incorporating pendent electron‐deficient perylene diimide (PDI) moieties on the side chains, indicating more efficient photoinduced electron transfer. Electrochemical measurements revealed that the PDI‐containing copolymers displayed reasonable
2,7-Carbazole-1,4-phenylene Copolymers with Polar Side Chains for Cathode Modifications in Polymer Light-Emitting Diodes
作者:Xiaofeng Xu、Bing Han、Junwu Chen、Junbiao Peng、Hongbin Wu、Yong Cao
DOI:10.1021/ma200191p
日期:2011.6.14
Alcohol-soluble 2,7-carbazole-1,4-phenylene copolymers PCP-NOH and PCP-EP, comprising surfactant-like diethanolamino and phosphonate end groups on the side chains, respectively, were synthesized and utilized as electron injection layer (EIL) in combination with high work function Al electrode in polymer light-emitting diodes (PLEDs). The UV-vis absorption and photoluminescence properties of the PCP-NOH and PCP-EP are mainly determined by the conjugated 2,7-carbazole-1,4-phenylene main chain. The PCP-NOH and PCP-EP possess comparable HOMO levels of -5.20 eV and LUMO levels arround -2.35 eV. Multilayer PLEDs with a device configuration of ITO/PEDOT:PSS (40 nm)/emissive layer (70 nm)/EIL (15 nm)/Al (100 am) were successfully fabricated. With fluorescent PFO-DBT15 as the emissive layer, the PLEDs using the PCP-NOH and PCP-EP as the EIL displayed luminous efficiency.(LE) of 1.01 and 0.88 cd/A, respectively, all obviously higher than 0.015 cd/A for sole Al cathode and 0.58 cd/A for the well-known Ba/Al cathode. With a phosphorescent Ir(mppy)(3)-doped polymer blend (PVK:PBD:Ir(mppy)(3) = 100:30:1) as the emissive layer, the PLEDs with the EIL showed high maximum LE of 39.3 cd/A for PCP-NOH and 42.5 cd/A for PCP-EP, in comparison to 0.35 cd/A for sole Al cathode and 32.2 cd/A for the Ba/Al cathode. Particularly, the PLED with PCP-EP as EIL exhibited an excellent LE of 33.3 cd/A at a current density of 61.1 mA/cm(2) (luminance = 20 300 cd/cm(2)), showing weak roll-off of efficiency at high current density. Inserting the polar alcohol-soluble polymers as interlayer can significantly increase built-in potentials in the PLEDs, from which electron injection barrier from the Al electrode is decreased. The results indicate that the PCP-NOH and PCP-EP are excellent electron injection polymers for high-performance PLEDs with high work function Al electrode.