有机小分子太阳能电池实验教学平台建设

采用真空热蒸镀方法制备有机小分子太阳能电池并测试其光电性能,使学生了解有机小分子太阳能电池的结构及制备工艺,熟悉Keithley半导体测试仪的使用方法,绘制器件的电流电压曲线,计算有机小分子太阳能电池的各项性能参数;通过对器件中每一层薄膜的制备和功能的分析,理解太阳能电池的结构和工作原理,并运用于工艺实验环节,着力提升学生的实践能力。

可溶液加工对称A-D-A有机小分子太阳能电池给体材料研究进展

20世纪以来,随着科技的进步和人类社会的发展,非再生传统化石能源日渐短缺,并且化石能源的使用也带来各种环境污染问题。因此,开发绿色无污染的新能源已成为世界各国研究的重点。基于硅等无机半导体材料的传统太阳能电池不仅生产工艺复杂,成本过高,而且会引起环境污染问题。近10年来,有机小分子太阳能电池的研究和应用发展迅速,其因优异的光电转换性能受到学者们的广泛关注。目前基于小分子材料的有机太阳能电池的光电转换效率最高已达到16%~17%。给体材料是太阳能电池活性层中的重要组成部分,不仅是小分子太阳能电池研究的关键基础,也是有机光伏器件未来产业化应用需要考虑的关键。选择合适的电子给体小分子与电子受体材料进行有效结合,可以优化器件的光吸收能力和调节电化学能级匹配度,是提高太阳能电池光电转化效率的关键。目前有机小分子给体材料主要分为非对称型电子推拉结构和对称型给体-受体-给体(或受体-给体-受体结构)。其中,以噻吩衍生物为主的对称结构小分子因其优异共轭平面性、高电荷传输率和可修饰性分子结构等优点而备受关注。本文主要对可溶液加工对称结构小分子太阳能电池给体材料进行了归纳总结,主要有寡聚噻吩类、苯并二噻吩类、吡咯并吡咯二酮类、二噻吩并噻咯类和卟啉类给体材料等。通过阐述已有对称小分子给体材料的研究进展,对比分析各种小分子给体材料的优缺点,展望小分子给体材料在有机光伏领域中的发展趋势和研究前景。

活性层优化对有机小分子太阳能电池的影响

首先制备了给体(Al Pc Cl)和受体(C70)比例为1∶1的电池器件并采用不同的温度对电池进行退火处理,发现在120℃的温度下退火电池器件的性能最好,器件的转换效率从2.28%提高到2.47%,增加了8.3%。为进一步优化电池器件的性能,制备了在相同的活性层厚度下不同的给受体比例的电池器件,发现在给受体的厚度之比为1∶5时器件性能最好,电池开路电压为0.8 V,短路电流为10.21 m A/cm^2,填充因子为46.04%,转换效率为3.71%。

新型含DPP结构单元的有机小分子化合物的合成

有机小分子太阳能电池材料因价格低廉,材料多样且易合成等优点而备受关注。近年,由给电子结构单元和吸电子结构单元连接的有机小分子太阳能电池材料由于能促进分子内电荷分离,降低分子能级,引起了人们广泛的关注。本文选取吡咯并吡咯二酮(DPP)为中心吸电子单元,甲氧基萘为给电子单元利用C-C直接偶联的方法成功了合成了一种新型D-A-D型有机小分子太阳能电池光伏材料。并利用紫外吸收光谱研究了其光物理性能。结果表明该化合物的紫外吸收光谱的最大吸收波长为800 nm。

有机太阳能电池材料研究新进展

介绍了有机太阳能电池研究的背景、基本原理、分类,并对有机太阳能电池材料进行了全面综述,包括小分子太阳能电池材料、大分子太阳能电池材料、D-A体系材料和有机无机杂化体系材料.

Ultrafast Electron Transfer in All-Small-Molecule Photovoltaic Blends Promoted by Intermolecular Interactions in Cyanided Donors

Cyano substitution has been established as a viable approach to optimize the performance of all-small-molecule organic solar cells.However,the effect of cyano substitution on the dynamics of photo-charge generation remains largely unexplored.Here,we report an ultrafast spectroscopic study showing that electron transfer is markedly promoted by enhanced intermolecular charge-transfer interaction in all-small-molecule blends with cyanided donors.The delocalized excitations,arising from intermolecular interaction in the moiety of cyano-substituted donor,undergo ultrafast electron transfer with a lifetime of∼3 ps in the blend.In contrast,some locally excited states,surviving in the film of donor without cyano substitution,are not actively involved in the charge separation.These findings well explain the performance improvement of devices with cyanided donors,suggesting that manipulating intermolecular interaction is an efficient strategy for device optimization.

A chlorinated low-bandgap small-molecule acceptor for organic solar cells with 14.1% efficiency and low energy loss

A new acceptor-donor-acceptor(A-D-A) type small-molecule acceptor NCBDT-4 Cl using chlorinated end groups is reported.This new-designed molecule demonstrates wide and efficient absorption ability in the range of 600–900 nm with a narrow optical bandgap of 1.40 eV. The device based on PBDB-T-SF:NCBDT-4 Cl shows a power conversion efficiency(PCE) of 13.1%without any post-treatment, which represents the best result for all as-cast organic solar cells(OSCs) to date. After device optimizations, the PCE was further enhanced to over 14% with a high short-circuit current density(Jsc) of 22.35 m A cm-2 and a fill-factor(FF) of 74.3%. The improved performance was attributed to the more efficient photo-electron conversion process in the optimal device. To our knowledge, this outstanding efficiency of 14.1% with an energy loss as low as 0.55 eV is among the best results for all single-junction OSCs.

Effect of electron-withdrawing units on triphenylamine-based small molecules for solution-processed organic solar cells

Organic small molecules （TPA-BT3T, TPA-PT3T, and TPA-DFBT3T） using triphenylamine as a donor unit, terthiophene as a bridge, and benzo-2,1,3-thiadiazole （BT）, [1,2,5]thiadiazolo[3,4-e]pyridine （PT） or 5,6-difluorobenzo[c][1,2,5]thiadiazole （DFBT） as an acceptor unit were designed and synthesized through Suzuki coupling reactions. These molecules exhibited good thermal stability with decomposition temperatures over 380℃ and broad absorption from 300 to 700 nm. Photovoltaic devices were fabricated with these small molecules as donors and PC71BM as an acceptor. The TPA-BT3T based devices exhibited a power conversion efficiency of 2.89%, higher than those of the TPA-PT3T- and TPA-DFBT3T-based devices （1.34% and 1.54% respectively）. The effects of electron-withdrawing units on absorption, energy level, charge transport, morphology, and photovoltaic properties also were investigated.

A series of dithienobenzodithiophene based small molecules for highly efficient organic solar cells

Three acceptor-donor-acceptor （A-D-A） small molecules DCAODTBDT, DRDTBDT and DTBDTBDT using dithieno[2,3-d：2＇,3＇-d＇]benzo[1,2-b：4,5-b＇]dithiophene as the central building block, octyl cyanoacetate, 3-octylrhodanine and thiobarbituric acid as the end groups were designed and synthesized as donor materials in solution-processed photovoltaic cells （OPVs）. The impacts of these different electron withdrawing end groups on the photophysical properties, energy levels, charge carrier mobility, morphologies of blend films, and their photovoltaic properties have been systematically investigated. OPVs device based on DRDTBDT gave the best power conversion efficiency （PCE） of 8.34%, which was significantly higher than that based on DCAODTBDT （4.83%） or DTBDTBDT （3.39%）. These results indicate that rather dedicated and balanced consideration of absorption, energy levels, morphology, mobility, etc. for the design of small-molecule-based OPVs （SM-OPVs） and systematic investigations are highly needed to achieve high performance for SM-OPVs.