基于异靛青的聚合物场效应晶体管材料研究进展

20世纪80年代以来,有机电子学领域的研究取得了很大进展.有机半导体材料凭借其成本低、质量轻、柔性好、易修饰、可大面积溶液加工等特点吸引了学术界以及工业界的极大关注.其中,第三代有机共轭聚合物,给-受体(Donor-Acceptor,简称D-A)共轭聚合物材料的发展尤为迅速.最近,以异靛青(Isoindigo,IID)类结构作为受体片段的D-A共轭聚合物被发现具有优异的性能,特别是在聚合物场效应晶体管器件中获得了最高3.62 cm~2·V~(-1)·s~(-1)的空穴迁移率,其衍生物获得14.4 cm~2·V~(-1)·s~(-1)的空穴迁移率,具有良好的应用前景.综述了近年来国内外关于异靛青结构在聚合物场效应晶体管材料中的应用,对其分子结构设计、器件制备以及构效关系做了详细介绍,希望为今后异靛青类化合物的应用拓展提供指导思路.     

基于含氟异靛蓝的硼氮配位键高分子电子受体

采用含氟异靛蓝单元(fIID)和硼氮配位键桥联噻吩联噻唑单元(BNTT)交替共聚制备了高分子电子受体,聚(N,N'-双(2-庚基十二烷基)-含氟异靛蓝-co-双苯基硼氮配位键桥联噻吩联噻唑)(P-BN-fIID)。采用理论计算、紫外-可见吸收光谱、循环伏安测试以及掠入射X射线衍射等研究了材料的结构与性质的关系,并制备了全高分子太阳能电池器件,研究了其光伏性能。结果表明:与基于异靛蓝单元(IID)的高分子聚(N,N'-双(2-己基辛基)-异靛蓝-co-双苯基硼氮配位键桥联噻吩联噻唑)(P-BN-IID)相比较,含有氟原子的P-BN-fIID的最低未占据分子轨道能级(ELUMO)降低了0.1 eV,吸收光谱红移了25 nm;同时,P-BN-fIID的结晶性明显提高,具有相对紧密的堆积结构和较高的电子迁移率。采用经典的高分子给体聚(2-烷硫基噻吩取代的二维共轭苯并二噻吩-co-噻吩桥联苯并三氮唑)(J61)与P-BN-fIID共混组装的全高分子太阳能电池器件,其能量转化效率(PCE)为2.83%。说明氟原子可以有效调节高分子受体的光电性质和结晶性,高分子受体的结晶行为明显影响全高分子太阳能电池的器件性能。     

高迁移率聚合物半导体材料最新进展

自20世纪80年代以来,聚合物半导体材料及其薄膜场效应晶体管器件(OFETs)已取得系列突破性进展.目前,已有数百种聚合物半导体材料被成功应用于OFETs中,空穴迁移率值最高已达36.3 cm~2·V~(-1)·s~(-1),可与有机小分子半导体材料甚至可同无定形硅相媲美.综述了近年来国内外高迁移率聚合物半导体的最新进展.分类对比总结和评述了空穴传输型(p-型)、电子传输型(n-型)和双极传输型聚合物半导体材料,并对聚合物半导体材料分子设计思路、薄膜OFETs器件制备及其性能参数进行了重点阐述.同时,总结了聚合物半导体材料的分子结构、聚集态结构与OFETs器件性能之间的内在关系,为今后设计与合成综合性能优异的聚合物半导体材料提供一定理论指导.     

两种四噻吩并萘分子晶体电荷传输性质的理论研究

采用密度泛函理论(DFT)方法结合不相干的电荷跳跃模型和随机Monte Carlo模拟,研究了2种四噻吩并萘晶体(AT1和AT2)的分子结构、电子性质及电荷载流子传输参数,并预测了这2种晶体室温下空穴和电子迁移率的各向异性.结果表明标题化合物具有近似平面的刚性骨架结构,电荷传输过程中分子的结构弛豫相当小.基于绝热势能面法计算的AT1和AT2分子空穴/电子传输内重组能分别为9.300×10~(-2)/1.100×10~(-1)eV和1.020×10~(-1)/1.290×10~(-1) eV,外重组能分别为1.835×10~(-2)/1.711×10~(-2) eV和1.857×10~(-2)/1.747×10~(-2) eV.利用Monte Carlo随机模拟方法预测的2种分子晶体室温(300K)下空穴/电子迁移率平均值分别为4.976×10~(-3)/2.766×10~(-2) cm~2 V~(-1)s~(-1)和3.857×10~(-3)/1.478×10~(-2)cm~2 V~(-1)s~(-1).此外,迁移率的角度依赖性研究表明2种载流子在AT1和AT2晶体aob平面传输时表现出显著的各向异性,其最大值均沿着电荷传输积分最大的方向,为制备高性能场效应晶体管器件提供了参考.     

哒嗪并吡咯二酮共轭聚合物半导体材料的合成及晶体管性能

采用Stille交叉偶联反应,合成了基于6-烷基吡咯[3,4-d]哒嗪-5,7-二酮(PPD)与吡咯并吡咯二酮(DPP)结构单元的受体-π-受体(A_1-π-A_2)型共轭聚合物(PPPD-DPP)。采用热重分析仪、紫外分光光度计、电化学工作站等表征了聚合物PPPD-DPP的性能,系统地研究了聚合物的热性能、光物理性能、电化学性能及晶体管性能。结果表明:聚合物PPPD-DPP具有良好的热稳定性,热分解温度达到376℃;薄膜的最大吸收峰位于702nm,光学能带隙为1.27eV;有较低的最高占据分子轨道能级(HOMO,-5.23eV)。基于PPPD-DPP的有机薄膜晶体管(OTFTs)器件在真空中显示出双极性传输特性,最高电子和空穴迁移率分别为0.030 cm~2/(V·s)和0.054cm~2/(V·s),在空气中PPPD-DPP器件则表现出明显的p型传输特性,空穴迁移率提升至0.121cm~2/(V·s)。     

苯并二噻吩/苯并噻二唑ADA型光电化合物:氟取代的影响

在其组成的共轭基元上进行氟取代是有机光电材料功能修饰的常见策略之一.在前期苯并二噻吩/苯并噻二唑ADA型小分子光电化合物基础上,在两个苯并噻二唑基元上引入不同个数的氟取代基,考察氟修饰位置和个数对其基本性质、场效应晶体管和光伏性能的影响.研究表明,随着氟原子数目的增加,化合物的溶解性能降低,热稳定性提高,最高占有轨道和最低空轨道能级降低,但光谱吸收范围变化不大.有机场效应晶体管器件测试表明,当苯并噻二唑单氟代且位于外侧位点时,化合物的空穴迁移率有所降低;当苯并噻二唑双氟代时,迁移率得到了明显提高,达到0.27cm~2·V~(-1)·s~(-1).光伏器件研究发现,氟原子的引入提高了器件的开路电压,但活性层形貌变差,最终导致短路电流密度和电池效率下降.     

基于硫杂萘二酰亚胺的席夫碱型聚合物电子传输材料

将苯甲醛基团引入到硫杂萘二酰亚胺共轭骨架中,与不同共轭程度和刚性的芳香二胺进行缩合反应,构筑了一类基于硫杂萘二酰亚胺的席夫碱型聚合物P1、P2、P3。采用紫外-可见吸收光谱(UV-Vis)、循环伏安等研究了材料的基本物理化学性质。这类聚合物具有良好的成膜性和较低的最低未占分子轨道能级(-4.07～-4.19 eV)。聚合物P3含有刚性萘单元,其UVVis的最大吸收波长(λ_(max))为754 nm,比P1和P2分别红移了约76 nm和75 nm。X射线衍射(XRD)表明,聚合物P1、P2、P3的薄膜均呈现无定形的特征。以溶液甩膜法制备了此类聚合物的有机场效应晶体管(OFET)器件,其中聚合物P3的薄膜经300℃热退火,其OFET器件的电子迁移率可达2.47×10~(-3) cm~2/(V·s),开关比为10~5,表明聚合物P3是一种可耐高温处理的n-型半导体材料。在聚合物共轭骨架中引入刚性的结构单元,可以有效调控吸收光谱、能级结构和薄膜形貌,进而提升OFET器件性能。     

新型环合靛蓝衍生物的合成及性质

设计合成了基于环合靛蓝单元的Donor-Acceptor(D-A)型小分子——2,2'-(-(((2,9-双(5-(2-癸基十四烷基)噻吩-2-基)-6,13-二氧代-6,13-二氢二吲哚[3,2,1de:3',2',1'-ij][1,5]萘啶-7,14-二基)双(噻吩-5,2-二基))双(甲基叉))双(3-氧-2,3-二氢-1H-茚-2,1-二叉))二丙二腈(MT-BAI-TM).采用密度泛函(DFT)理论计算了该化合物的前线分子轨道分布.利用紫外-可见吸收光谱和循环伏安法分析了化合物的能级和带隙特征;通过掠入射宽角X射线散射实验(GIWAXS)测试了旋涂薄膜样品S-1内MT-BAI-TM分子的堆积取向.MT-BAT-TM的深吸收、高电子亲和势及面向上(Face-on)堆积特征表明,其具有受体型有机半导体材料的性质.     

侧链含自由基单元的1,4-吡咯并吡咯二酮共轭聚合物的合成和半导体性质研究

合成了两个侧链含有2,2,6,6-四甲基哌啶-1-氧自由基单元(TEMPO)的1,4-吡咯并吡咯二酮(DPP)共轭聚合物PDPP4T-1和PDPP4T-2,并开展了其半导体性质研究。薄膜场效应晶体管器件测试结果显示,相对于不含TEMPO的聚合物PDPP4T,PDPP4T-1和PDPP4T-2的场效应器件性能有所降低,不过,含TEMPO的聚合物器件性能最高仍达到了2.12cm~2·V~(-1)·s~(-1)。进一步通过原子力显微镜和X射线衍射对TEMPO引入后导致性能降低的可能原因进行了研究。     

Rhodanine flanked indacenodithiophene as non-fullerene acceptor for efficient polymer solar cells

A fused-ring electron acceptor IDT-2BR1 based on indacenodithiophene core with hexyl side-chains flanked by benzothiadiazole rhodanine was designed and synthesized.In comparison with its counterpart with hexylphenyl side-chains(IDT-2BR),IDT-2BR1exhibits higher highest occupied molecular orbital(HOMO)energy but similar lowest unoccupied molecular orbital(LUMO)energy(IDT-2BR1:HOMO=-5.37eV,LUMO=-3.67eV;IDT-2BR:HOMO=-5.52eV,LUMO=-3.69eV),red-shifted absorption and narrower bandgap.IDT-2BR1 has higher electron mobility(2.2×10~(-3)cm~2 V~(-1)s~(-1))than IDT-2BR(3.4×10~(-4)cm~2 V~(-1)s~(-1))due to the reduced steric hindrance and ordered molecular packing.Fullerene-free organic solar cells based on PTB7-Th:IDT-2BRl yield power conversion efficiencies up to 8.7%,higher than that of PTB7-Th:IDT-2BR(7.7%),with a high open circuit voltage of0.95 V and good device stability.     

新型共轭聚合物的设计合成及其在场效应晶体管的应用

近年来,有机场效应晶体管(OFETs)由于在柔性器件和可穿戴电子学中的潜在应用受到了学术界和工业界的普遍关注,尤其是以聚合物半导体材料构筑的晶体管性能得到了快速的发展.如何设计合成用于OFETs的高性能聚合物半导体材料,一直是我们的追求目标.然而,分子结构对迁移率的影响仍缺少系统的比较.本文综述了近年来国内外新型聚合物材料的最新进展.我们按照材料的种类以及载流子的传输类型进行了分类,对高性能聚合物材料的发展过程、材料的设计思路以及相应的FETs性能进行了系统地归纳总结.通过研究分子及分子聚集态结构与器件性能之间的关系,希望为以后设计合成新型的高性能的聚合物材料提供有益的借鉴和指导.     

High charge carrier mobility in conjugated organometallic polymer networks

The improvement of charge transport in conjugated polymers is a focal point of current research. It is shown here that the carrier mobility can be substantially increased through the introduction of conjugated cross-links between the conjugated chains. Novel organometallic polymer networks based on a poly(p-phenylene ethynylene) (PPE) derivative and Pt0 were synthesized by ligand-exchange reactions between the linear PPE and a low-molecular Pt complex. Time-of-flight measurements revealed ambipolar charge carrier mobilities of up to 1.6 x 10-2 cm2 V-1 s-1 for these materials, which are an order of magnitude higher than those of the neat polymer and represent the highest mobilities yet observed in disordered conjugated polymers.     

含二噻吩并[3,2-b:2',3'-d]氧膦杂环戊二烯共轭聚合物的合成及其在薄膜晶体管和体异质结太阳能电池中的应用

采用Stille缩聚反应,合成了3,5-二烷基-二噻吩并[3,2-b:2',3'-d]氧膦杂环戊二烯与二联噻吩的共聚物P1和P2,系统研究了它们的热性能、电化学性质和光物理性质.结果表明,这2个聚合物具有良好的热稳定性,热分解温度均大于400℃;薄膜的最大吸收峰位于590 nm,光学带隙为1.76 eV.将P1和P2作为活性层制备了薄膜晶体管和体异质结太阳能电池,发现带有较长烷基链的P2的器件性能较好.在底栅、顶接触结构的薄膜晶体管中,P2的空穴迁移率最高达到0.0077 cm2V-1s-1;在AM 1.5 G 100 mW/cm2光照条件下,P2的光伏电池的开路电压为0.68 V,短路电流为7.9 mA/cm2,填充因子为52%,能量转换效率为2.8%.     

Regioirregular ambipolar naphthalenediimide‐based alternating polymers: Synthesis,characterization, and application in field‐effect transistors

In this work, we report the synthesis, characterization, and application of two regioirregular naphthalenediimide (NDI)‐based alternating conjugated polymers, namely P1 and P2 , in which nitrile‐substituted moiety, 2,3‐bis(thiophen‐2‐yl)acrylonitrile and NDI moiety act as donor and acceptor unit, respectively. The two regioirregular polymers possess low‐lying LUMO energy levels of ?3.92 eV for P1 and ?3.96 eV for P2 . Both polymers possess typical dual‐band UV?Vis?NIR absorption profiles of NDI‐based polymers, and show broadened and red‐shifted absorption spectra in the solid state compared with those in solutions. Field‐effect transistor devices with top‐gate bottom‐contact configuration were used to evaluate the polymers' semiconducting properties. The two polymers exhibited promising and air‐stable ambipolar charge transport characteristics. Thin film microstructure investigations (AFM and 2D‐GIXRD) suggest both polymers formed continuous and smooth thin films, and adopted predominantly face‐on molecular packing in the solid state. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3627–3635     

High-performance air-stable organic field-effect transistors: isoindigo-based conjugated polymers

Two conjugated polymers, IIDDT and IIDT, based on an isoindigo core were developed for organic field-effect transisitors. Investigation of their field-effect performance indicated that IIDDT exhibited air-stable mobility up to 0.79 cm(2) V(-1) s(-1), which is quite high among polymer FET materials. The facile preparation and high mobility of such polymers make isoindigo-based polymers very promising for application as solution-processable organic semiconductors for optoelectronic devices.     

含Ullazine结构基元的共轭聚合物的合成及其光电性能研究

将Ullazine结构基元引入到聚合物主链或侧链中,分别与吡咯并吡咯二酮(DPP)、2,5-双(三甲基锡)噻吩共聚得到了二元共聚物PB和三元共聚物PT,分别利用凝胶渗透色谱和热重分析表征了聚合物的分子量和热稳定性,并研究了聚合物的光物理、电化学和光伏性能.基于共聚物PB和PT作为电子给体材料的聚合物太阳能电池器件测试结果表明,二元共聚物PB由于具有较低的能级水平从而获得较高开路电压,而侧链含Ullazine结构基元的三元共聚物PT具有更宽的吸收光谱和更高的空穴迁移率,获得了更高的短路电流和能量转换效率.     

An n-Type Polythiophene Derivative with Excellent Thermoelectric Performance

Typical n-type conjugated polymers are based on fused-ring electron-accepting building blocks. Herein, we report a non-fused-ring strategy to design n-type conjugated polymers, i.e. introducing electron-withdrawing imide or cyano groups to each thiophene unit of a non-fused-ring polythiophene backbone. The resulting polymer, n-PT1 , shows low LUMO/HOMO energy levels of −3.91 eV/−6.22 eV, high electron mobility of 0.39 cm² V⁻¹ s⁻¹ and high crystallinity in thin film. After n-doping, n-PT1 exhibits excellent thermoelectric performance with an electrical conductivity of 61.2 S cm⁻¹ and a power factor (PF) of 141.7 μW m⁻¹ K⁻². This PF is the highest value reported so far for n-type conjugated polymers and this is the first time for polythiophene derivatives to be used in n-type organic thermoelectrics. The excellent thermoelectric performance of n-PT1 is due to its superior tolerance to doping. This work indicates that polythiophene derivatives without fused rings are low-cost and high-performance n-type conjugated polymers.     

Synthesis and characterization of thieno[3,2‐b]thiophene‐isoindigo‐based copolymers as electron donor and hole transport materials for bulk‐heterojunction polymer solar cells

A novel class of thieno[3,2‐b]thiophene (TT) and isoindigo based copolymers were synthesized and evaluated as electron donor and hole transport materials in bulk‐heterojunction polymer solar cells (BHJ PSCs). These π‐conjugated donor‐acceptor polymers were derived from fused TT and isoindigo structures bridged by thiophene units. The band‐gaps and the highest occupied molecular orbital (HOMO) levels of the polymers were tuned using different conjugating lengths of thiophene units on the main chains, providing band‐gaps from 1.55 to 1.91 eV and HOMO levels from ?5.34 to ?5.71 eV, respectively. The corresponding lowest unoccupied molecular orbital (LUMO) levels were appropriately adjusted with the isoindigo units. Conventional BHJ PSCs (ITO/PEDOT:PSS/active layer/interlayer/Al) with an active layer composed of the polymer and PC₇₁BM were fabricated for evaluation. Power conversion efficiency from a low of 1.25% to a high of 4.69% were achieved with the best performing device provided by the D?π?A polymer with a relatively board absorption spectrum, high absorption coefficient, and more uniform blend morphology. These results demonstrate the potential of this class of thieno[3,2‐b]thiophene‐isoindigo‐based polymers as efficient electron donor and hole transport polymers for BHJ PSCs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

An isoindigo-based low band gap polymer for efficient polymer solar cells with high photo-voltage

A new low band gap polymer (E(g) = 1.6 eV) with alternating thiophene and isoindigo units was synthesized and characterized. A PCE of 3.0% and high open-circuit voltage of 0.89 V were realized in polymer solar cells, which demonstrated the promise of isoindigo as an electron deficient unit in the design of donor-acceptor conjugated polymers for polymer solar cells.     

Synthesis and characterization of dithienylbenzobis(thiadiazole)-based low band-gap polymers for organic electronics

New donor-acceptor alternating conjugated polymers were synthesized and characterized. Among them, PCPBBT exhibited a band-gap of 1.01 eV and ambipolar characteristics with μ(h) = 7.1 × 10(-4) cm(2) V(-1) s(-1) and μ(e) = 3.3 × 10(-3) cm(2) V(-1) s(-1).