【作者】 赵巍；

【导师】 杨伟；

【作者基本信息】 华南理工大学 ， 高分子化学与物理， 2010， 博士

【摘要】 共轭聚合物由于在聚合物太阳电池领域潜在的用途而受到广泛关注。经过近几年的研究,聚合物太阳电池的效率已经达到了4~7%的水平,但要在市场上广泛应用,其能量转换效率还是偏低。而现今,合成新型的、具有可见光至近红外吸收的共轭聚合物给体材料,对于提高聚合物太阳电池器件吸收光谱对太阳光谱的匹配,从而提高聚合物太阳电池的能量转换效率具有重要意义。聚咔唑及衍生物由于含有一个刚性的平面内联苯单元,其热稳定性及化学稳定性都较高;聚咔唑衍生物具有较高的空穴迁移率、较低的HOMO能级,使得基于聚咔唑衍生物的太阳电池器件的开路电压较高;另外,咔唑的N原子易于发生烷基链取代反应,可以显著增强聚合物溶解性和可加工性,使得聚咔唑及衍生物成为一类受到广泛关注的聚合物给体材料。咔唑可以很容易通过与其它单体共聚的方法调节聚合物的吸收和发射波长。通过和吸电子单元的共聚,在主链上形成交替的D-A结构,由于在聚合物主链上分子内的电荷转移效应,可以使聚合物的吸收光谱发生显著的红移,从而覆盖更宽的太阳光谱范围,使得太阳辐射中波长较长的光子也可以在太阳电池器件中被吸收。基于这种思路,通过Suzuki缩聚反应将具有强吸电子能力的窄带隙单元5,5-(4′,7′-双(噻吩-2-基)-2′,1′,3′-苯并硒二唑(DBSe)、2,5-二(3-辛基噻吩-2-基)-噻唑[5,4-d]噻唑(Tz)、5,7-二(噻吩-2-基)噻[3,4-b]并[1,4]二嗪(DTP)、2,3-二甲基-5,7-二(2-噻吩基)噻[3,4-b]并[1,4]二嗪(DMTP)、4,7-二(3,4-乙二氧撑噻吩-2-基)-2,1,3-苯并噻二唑(EBTE)引入咔唑主链,使聚合物具有更宽的光谱响应,从而能够吸收、利用更多的太阳光子。在第三章中,制备了2,7-咔唑与DBSe的交替共聚物PCzDBSe。聚合物的光谱响应达到了750nm,与其含硫的的同系物(PCDTBT)相比,光谱响应红移了56nm。FET测试结果表明PCzDBSe的空穴迁移率为3.9×10-4cm~2V-1s-1。PCzDBSe与PC71BM按重量比1:4共混膜制备的太阳电池器件,在模拟太阳光AM1.5(100mW/cm~2)条件下,得到的器件数据如下:Jsc = 7.23mA/cm~2,Voc = 0.75V,FF = 45%,光电转换效率ECE = 2.58%。说明该类材料是一种很有前途的聚合物太阳电池用共轭聚合物给体材料。在第四章中,将2,7-咔唑与Tz和DBT共聚,控制Tz和BDT的投料比,得到了五种共聚物。通过控制Tz和DBT的相对含量,对聚合物的吸收光谱进行了调节。结果表明,随着DBT相对含量的增加,聚合物的吸收光谱逐渐红移,当DBT相对含量为37.5%时,吸收光谱响应红移最大,到了696nm。与DBT相对含量为50%时的聚合物PCzDBT的光谱响应(668nm)相比,向长波方向移动了28nm。以这五种共聚物和PC61BM共混膜制备得到的太阳电池器件,在模拟太阳光AM1.5(100 mW/cm~2)条件下,得到了2.18~3.45%的能量转换效率;其中,以PCzTzDBT37为给体时,得到了最好的器件数据:Jsc = 6.27mA/cm~2,Voc = 0.85V,FF = 60.55%,光电转换效率ECE = 3.45%。在第五章中,将2,7-咔唑分别与噻[3,4-b]并[1,4]二嗪的衍生物DTP和DMTP共聚,得到了两种交替共聚物PCzDTP和PCzDMTP。其光谱响应扩展到了819nm(PCzDTP)和803nm(PCzDMTP)。由于DTP和DMTP的吸电子能力比DBT更强,与咔唑和DBT的交替共聚物(668nm)相比,PCzDTP和PCzDMTP吸收光谱分别红移了151nm和135nm。以这两种聚合物为给体的太阳电池器件,在模拟太阳光AM1.5 (100 mW/cm~2)条件下,获得了0.4~1%的光电转换效率。噻[3,4-b]并[1,4]二嗪结构中的氢原子被甲基取代后,其热稳定性和外量子效率都有了增加,使其太阳电池器件的性能也有了提升。在第六章中,将2,7-咔唑与窄带隙单元EBTE共聚,得到交替共聚物PCzEBTE。与其噻吩的同系物相比,由于EDOT比噻吩供电子能力更强,使得PCzEBTE的带隙更窄,其光谱响应(726nm)比PCzDBT(668nm)红移了58nm。以PCzEBTE和PCBM按重量比1:4共混膜制备得到的太阳电池器件。在模拟太阳光AM1.5(100 mW/cm~2)条件下,得到的器件数据如下:Jsc = 2.22mA/cm~2,Voc = 0.8V,FF = 36%,光电转换效率ECE = 0.64%。更多还原

【Abstract】 π-conjugated polymers have attracted much attention for the pontential use as the donor materials in the polymer photovoltaic solar cells (PPVCs). Although the energy conversion efficiency of 4~7% of PPVCs have been achieved recently, it is necessary to improve the efficiency for commercial use. The optical active polymers, currently used in PPVCs devices are typically low bandgap conjugated polymer. In order to match solar terrestrial radiation, and thus improving the device efficiency, many researchers have foucsed on the synthesis of novel conjugated polymers with extending absorption.As compared with other conjugated polymer donors, poly(2,7-carbazole) derivatives (Cz) exhibit some unique merits such as excellent thermal stability duo to the rigid biphenyl structure, high hole mobility, low energy lying highest occupied molecular orbital (HOMO), and therefore can result in high air stability and high Voc. And the N-H could be modified by alkyl to give the polymer good solubility and processablity.The absorbency spectrum of poly(2,7-carbazole) derivatives could be tuned by copolymerization of 2,7-carbazole and other monomers. When copolymerized with low bandgap unit, the absorbency spectrum would red-shift because of the intramolecular charge transfer effect, thus enabling the photocurrent generation from lower energy photons.In this dissertation, the low bandgap units of 5,5-(4,7-di-2-thienyl-2,1,3-Benzoselenadia zole) (DBSe), 2,5-bis(3-octylthiophene-2-yl)-thiazole[5,4-d] thiazole (Tz), 5,7-(di-2-thienyl)- theno[3,4-b][1,4]pyrazine] (DTP), 2,3-dimethyl-5,7-(di-2-thienyl)-theno[3,4-b][1,4]pyrazine] (DMTP), 5,5-(4′,7′-di-3,4-ethylene dioxythiophene-2-yl)-2′,1′,3′-benzothiadiazole] (EBTE) were copolymerized with N-9′-heptadecanyl-2,7-carbazole by Suzuki polycondensation. And five series of low bandgap polymers were prepared to red-shift the absorbency spectrum of the copolymer.In charpter 3, alternating copolymer of Cz and DBSe (PCzDBSe) was synthesed. The spectrum response is extended to 750nm, which was 56nm red-shifted compared with its S analogue(PCDTBT). The hole mobility is estimated to be 3.9×10-4cm~2V-1s-1. Polymer solar cells (PSCs) based on the blends of PCzDBSe and [6,6]-phenyl-C71 butyric acid methyl ester (PC71BM) with a weight ratio of 1: 4 were fabricated. Under AM 1.5 (AM, air mass), 100 mW/cm~2 illumination, the devices were found to have an open-circuit (Voc) of 0.75V, a short-circuit current density (Jsc) of 7.23mA/cm~2, a fill factor (FF) of 45% and a power conversion efficiency (PCE) of 2.58%. The primary results indicate that PCzDBSe is a promising donor for polymer solar cells.In charpter 4, five copolymers based on Cz, Tz and DBT were prepared. The absorption of the polymer was red-shifted with the increasing content of DBT, and the spectrum response is extended to 696nm when the DBT content is 37.5%. Polymer solar cells were fabricated using the blend of the copolymer and PCBM as the active layer. Under AM 1.5(AM, air mass), 100 mW/cm~2 illumination, the bset device performances were recorded to be an open-circuit (Voc) of 0.85V, a short-circuit current density (Jsc) of 6.27mA/cm~2, a fill factor (FF) of 60.55% and a power conversion efficiency (PCE) of 3.45%, when the weight ratio of PCzTzDBT37:PCBM was 1:2.In charpter 5, Cz is copolymerized with DTP and DMTP The absorption response is extended to 819nm (PCzDTP) and 803nm (PCzDMTP). Polymer solar cells (PSCs) based on the blends of the two polymers and PCBM were fabricated. Under AM 1.5(AM, air mass), 100 mW/cm~2 illumination, a power conversion efficiency (PCE) of 0.41~0.99% was recorded. In charpter 6, Cz is copolymerized with EBTE. The spectrum response of PCzEBTE (726nm) is 58nm red-shift compared with its thiophene analogue PCzDBT, because the electron-donating effect of EDOT is stronger than thiophene. Polymer solar cells (PSCs) based on the blends of PCzEBTE and PCBM with a weight ratio of 1: 4 were fabricated. Under AM 1.5(AM, air mass), 100 mW/cm~2 illumination, the devices were found to have an open-circuit (Voc) of 0.8V, a short-circuit current density (Jsc) of 2.22mA/cm~2, a fill factor (FF) of 36% and a power conversion efficiency (PCE) of 0.64 %.更多还原