高相转变温度的离子凝胶电解质基准固态染料敏化太阳电池

染料敏化太阳电池(DSC)以其低价、高效等优势, 成为学术界和工业界的研究热点. 传统液态电解质由于易挥发、易泄漏等问题, 导致基于液态电解质的电池难以保持长期稳定, 影响光伏技术的应用. 本文合成了N,N'-1,5-戊二基双月桂酰胺, 将其作为有机小分子胶凝剂(LMOG)胶凝离子液体电解质(ILE)制备了离子凝胶电解质(IGE)并组装成准固态电池(QS-DSCs). 差示扫描量热测试显示该凝胶电解质的相转变温度(T_gel)为104.7℃, 具有良好的本征热稳定性.利用循环伏安法、电化学阻抗谱、调制光电压/光电流谱分别研究了液态电池和准固态电池内部电子传输和复合动力学过程. 结果表明, 凝胶电解质的三维网络结构加速了TiO₂光阳极/电解质界面电子与电解质中I₃^-的复合过程, 使电子寿命降低, 导致准固态电池的光电转换效率略低于液态电池. 在AM1.5 (100 mW·cm^-2)及50℃条件下的加速老化测试结果显示, 持续老化1000 h后其光电转换效率(η)无衰减,而液态电池的光电转换效率衰减为初始值的86%, 表明准固态电池具有良好的光热稳定性.     

硫基离子液体电解质拓宽量子点敏化太阳能电池的应用温度范围

制备了1-甲基-3-丙基咪唑硫离子液体电解质,并应用在量子点敏化太阳能电池中。通过优化S和Na₂S的浓度,电解质的电导率在25℃下达到了12.96 mS·cm^-1。差示扫描量热法分析表明离子液体电解质的玻璃化转变温度为-85℃。采用该电解质的量子点敏化太阳能电池在25℃下达到了3.03%的光电转化效率(η),与采用水基电解质的电池的效率3.34%接近。由于本文中的离子液体电解质具有低玻璃化转变温度和不易挥发的优点,采用离子液体电解质的量子点敏化太阳能电池在-20℃ (η=2.32%)及80℃ (η=1.90%)的温度下表现出了比水基电解质优异的光电转化性能。     

基于自催化策略原位构建高性能锂电池用凝胶电解质

凝胶聚合物电解质作为一种高锂离子传导效率的聚合物电解质而备受关注。然而，制备凝胶聚合物电解质的过程仍存在催化剂难以脱除、流程繁琐等问题。在本工作中，采用离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF₄)中潜在的Lewis酸诱导乙烯基醚类单体发生阳离子聚合的策略，探究出一种在电池内部原位构建高性能凝胶聚合物电解质的方法。BMIMBF₄的引入提升了凝胶聚合物电解质的电导率和电化学稳定性，基于该凝胶聚合物电解质的锂对称电池能在0.1 mA·cm^-2电流密度下循环500 h。由该凝胶聚合物电解质原位组装的全电池以1 C的倍率进行恒流充放电，循环100圈后容量保持率为90%;即使在10 C的高倍率下时，电池的放电比容量仍能保持在67.5 mAh·g^-1。该自催化策略为凝胶聚合物电解质的快速构建提供了新的思路。     

基于偏氟乙烯-六氟丙烯共聚物凝胶电解质的染料敏化太阳电池光电性能研究

采用偏氟乙烯-六氟丙烯共聚物[P(VDF-HFP)]胶凝3-甲氧基丙腈基液体电解质, 成功制备了凝胶电解质并组装成准固态染料敏化太阳电池. 差示扫描量热测试结果表明凝胶电解质的溶液-凝胶转变温度(TSG)为71 ℃. 利用电化学方法分析了凝胶电解质中 电对的表观扩散系数及电导率低于液体电解质的原因, 同时结合暗态伏安法考察了电池内部TiO2多孔薄膜电极/电解质界面处的暗反应, 分析了凝胶化对电池光伏性能的影响. 进一步老化实验结果表明凝胶电池的稳定性明显优于液体电池.     

1-甲基-3-己基咪唑碘在染料敏化太阳电池中的应用研究

利用超微铂电极和循环伏安法, 以及电化学阻抗谱研究了在1-甲基-3-己基咪唑碘(HMII)的3-甲氧基丙腈(MePN)溶液中I₃^－和I^－的氧化还原行为, 并对比了由不同浓度的I₂和HMII组成的电解质溶液对染料敏化纳米薄膜太阳电池(DSCs)光伏性能的影响. 发现以MePN为溶剂, 含1.0 mol•dm^－3 HMII, 0.12 mol•dm^－3 I₂, 0.10 mol•dm^－3 LiI和0.50 mol•dm^－3 4-叔丁基吡啶的电解质溶液, 其DSCs的短路光电流密度为14.06 mA•cm^－2, 开路电压为0.71 V, 填充因子为0.69, 光电转换效率达6.81%.     

离子液体基聚合物的结构对染料敏化太阳能电池性能的影响研究

设计合成了分别悬挂磺酸官能团、磺酸锂官能团和烷基链官能团的三种结构的离子液体基聚合物,用于聚合物凝胶电解质的制备,并应用于染料敏化太阳能电池中.结果发现这三种聚合物含量的变化对电池性能的影响有较大差别.悬挂普通烷基链官能团的离子液体基聚合物(P-CH₃I)的加入,由于增加了电解质的粘度,使得电池的性能随着P-CH₃I含量的增加而变差;悬挂磺酸锂官能团的离子液体基聚合物P-LiI加入使电池的性能略微下降,而悬挂磺酸官能团的离子液体基聚合物P-HI加入到离子液体电解质后,在一定浓度范围内能改善离子的扩散等性能,从而使基于这种离子液体基聚合物的电池的光电性能相对较好.并通过电解质AFM微观形貌的研究解释了这三类电解质中离子扩散的差异以及光电性能的差别.     

添加剂对染料敏化太阳电池电解质性能的影响

以N-甲基咪唑、苯并咪唑、叔丁基吡啶和离子液体1-甲基-3-乙基咪唑三氟乙酸盐(EMITA)作为染料敏化太阳电池(DSCs)电解质溶液中的添加剂, 使用超微电极通过循环伏安法研究其对液体电解质中I-3和I-氧化还原行为的影响, 通过电化学阻抗谱研究了上述四种添加剂对Pt电极电解质界面的影响. 结果表明, 添加剂EMITA的加入使I-3在电解质中的扩散系数减小, Pt电极电解质界面上的界面传输电阻Rct增大, 电解质的电阻降低; 光伏性能测试表明, EMITA的添加提高了DSCs的开路电压和填充因子, 其DSCs的光电转换效率达到了5.72%.     

染料敏化太阳能电池TiO2电极的制备及电解质的影响

采用溶胶-凝胶水热法制备了锐钛矿型纳米晶TiO₂薄膜电极,在乙二醇碳酸酯(EC)/1,2-丙二醇碳酸酯(PC)电解液体系中,研究了I₂和KI含量对电极光电性能的影响,发现随着电解液中I₂含量的增加,电池的短路光电流呈现先增加后减小的趋势,但光电流增加和减少的幅度并不大,同时体系的暗电流不断增加,光电压不断下降;随着电解液中KI含量的增加,电池的短路光电流也不断增加,当KI的含量大于0.2 mol/L时,电池的短路光电流的增加的趋势减缓.并对电解液中I₂和KI含量对电池光电性能影响的原因进行了初步的探讨.     

TiO2薄膜光催化氧化I-的研究

采用溶胶凝胶法,在玻璃珠表面涂覆均匀透明的TiO₂薄膜并制成光催化反应器,对水溶液中I-的光催化氧化进行了研究.比较了光催化剂的活性,讨论了I^-的起始浓度、试液的酸度、光照时间与I₂产率的关系.实验结果表明:采用锐钛型TiO₂作光催化剂(3L碘化钾溶液所用催化剂量为40g),当[I^-]=0.3mol/L,[H⁺]=3.0mol/L,光照8h时,I₂的产率达到41.26%.     

聚乙烯吡咯烷酮基碘凝胶电解质的制备及在染料敏化太阳能电池中的应用

采用聚乙烯吡咯烷酮(PVP)和聚偏氟乙烯(PVDF)为凝胶剂, 以碘化锂和碘单质为碘源, 碳酸乙烯酯(EC)和碳酸丙烯酯(PC)为溶剂, 制备了染料敏化太阳能电池(DSSCs)用凝胶聚合物电解质(GPE). 使用拉曼光谱、 循环伏安曲线和交流阻抗谱等对GPE进行表征. 结果表明, 聚合物的配比与浓度及碘与碘化锂比例对该电解质性能有很大影响, 当聚合物质量分数为10%、 PVP与PVDF质量比为80∶20、 I₂浓度为0.042 mol/L且LiI与I₂摩尔比为30∶1时, 制备的GPE在室温下电导率达最大值(3.27 mS/cm). 使用该GPE组装的DSSCs在100 mW/cm²的模拟太阳光照射下, 开路电压为0.64 V, 短路电流为13.6 mA/cm², 填充因子为0.595, 能量转化效率为5.18%, 并在30 d内表现出了良好的稳定工作性能.     

Dependence of solar cell performance on the nature of alkaline counterion in gel polymer electrolytes containing binary iodides

Performance of dye-sensitized nano-crystalline TiO₂ thin film-based photo-electrochemical solar cells (PECSCs) containing gel polymer electrolytes is largely governed by the nature of the cation in the electrolyte. Dependence of the photovoltaic performance in these quasi-solid state PECSCs on the alkaline cation size has already been investigated for single cation iodide salt-based electrolytes. The present study reports the ionic conductivity dependence on the nature of alkaline cations (counterion) in a gel polymer electrolyte based on binary iodides. Polyacrylonitrile-based gel polymer electrolyte series containing binary iodide salts is prepared using one of the alkaline iodides (LiI, NaI, KI, RbI, and CsI) and tetrapropylammonium iodide (Pr₄NI). All the electrolytes based on binary salts have shown conductivity enhancement compared to their single cation counterparts. When combined with Pr₄NI, each of the Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺ cation containing iodide salts incorporated in the gel electrolytes has shown a room temperature conductivity enhancement of 85.59, 12.03, 12.71, 20.77, and 15.36%, respectively. The conductivities of gel electrolytes containing binary iodide systems with Pr₄NI and KI/RbI/CsI are higher and have shown values of 3.28, 3.43, and 3.23 mS cm⁻¹, respectively at room temperature. The influence of the nature of counterions on the performance of quasi-solid state dye-sensitized solar cells is investigated by assembling two series of cells. All the binary cationic solar cells have shown more or less enhancements of open circuit voltage, short circuit current density, fill factor, and efficiency compared to their single cation counterparts. This work highlights the importance of employing binary cations (a large and a small) in electrolytes intended for quasi-solid state solar cells. The percentage of energy conversion efficiency enhancement shown for the PECSCs made with electrolytes containing Pr₄NI along with Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺ iodides is 260.27, 133.65, 65.27, 25.32, and 8.36%, respectively. The highest efficiency of 4.93% is shown by the solar cell containing KI and Pr₄NI. However, the highest enhancements of ionic conductivity as well as the energy conversion efficiency were exhibited by the PECSC made with Li⁺-containing binary cationic electrolyte.

     

染料敏化太阳电池用聚合物电解质

综述了本研究小组近年来用于染料敏化太阳电池中聚合物电解质的研究概况.设计合成了几类性能优良的聚合物电解质,较好地改进了液体电解质染料敏化太阳电池(DSSC)的使用稳定性,研究结果具有实际应用的价值,并提出了此领域研究今后的发展方向.     

Recent research progress on quasi-solid-state electrolytes for dye-sensitized solar cells

Dye-sensitized solar cells(DSSCs) are the most promising, low cost and most extensively investigated solar cells. They are famous for their clean and efficient solar energy conversion. Nevertheless this, long-time stability is still to be acquired. In recent years research on solid and quasi-solid state electrolytes is extensively increased. Various quasi-solid electrolytes, including composites polymer electrolytes, ionic liquid electrolytes,thermoplastic polymer electrolytes and thermosetting polymer electrolytes have been used. Performance and stability of a quasi-solid state electrolyte are between liquid and solid electrolytes. High photovoltaic performances of QS-DSSCs along better long-term stability can be obtained by designing and optimizing quasi-solid electrolytes. It is a prospective candidate for highly efficient and stable DSSCs.     

A novel composite polymer electrolyte containing room-temperature ionic liquids and heteropolyacids for dye-sensitized solar cells

A novel composite polymeric gel comprising room-temperature ionic liquids (1-butyl-3-methyl-imidazolium-hexafluorophosphate, BMImPF₆) and heteropolyacids (phosphotungstic acid, PWA) in poly(2-hydroxyethyl methacrylate) matrix was successfully prepared and employed as a quasi-solid state electrolyte in dye-sensitized solar cells (DSSCs). These composite polymer electrolytes offered specific benefits over the ionic liquids and heteropolyacids, which effectively enhanced the ionic conductivity of the composite polymer electrolyte. Unsealed devices employing the composite polymer electrolyte with the 3% content of PWA achieved the solar to electrical energy conversion efficiency of 1.68% under irradiation of 50 mW cm⁻² light intensity, increasing by a factor of more than three compared to a DSSC with the blank BMImPF₆-based polymer electrolyte without PWA. It is expected that these composite polymer electrolytes are an attractive alternative to previously reported hole transporting materials for the fabrication of the long-term stable quasi-solid state or solid state DSSCs.     

Photovoltaic performance of dye-sensitized solar cells assembled by in-situ chemical cross-linking

Quasi-solid state dye-sensitized solar cells (DSSCs) were assembled by in-situ chemical cross-linking of a gel electrolyte precursor containing liquid electrolyte. The DSSCs assembled with this cross-linked gel polymer electrolyte showed higher open circuit voltage and lower short-circuit photocurrent density than those of DSSCs with liquid electrolyte. Addition of SiO₂ nanoparticles into the cross-linked gel polymer electrolyte significantly improved the photovoltaic performance and long-term stability of the DSSCs. The optimized quasi-solid state DSSC showed high conversion efficiency, 6.2% at 100 mW cm^?2 with good durability.     

A 7.72% efficient dye sensitized solar cell based on novel necklace-like polymer gel electrolyte containing latent chemically cross-linked gel electrolyte precursors

Novel necklace-like polymer gel electrolytes containing latent chemically cross-linked gel electrolyte precursors were prepared for quasi-solid dye sensitized solar cells with a highest efficiency of 7.72% and an active area of 0.25 cm2 under AM1.5 condition at 100 mW cm(-2) irradiation.     

电化学阻抗谱研究聚合物凝胶电解质对染料敏化太阳能电池性能的影响

用甲基丙烯酸β-羟乙酯(HEMA)与N-乙烯基吡咯烷酮(NVP)共聚物P(HEMA-NVP)、甲基丙烯酸甲酯(MMA)与N-乙烯基吡咯烷酮共聚物P(MMA-NVP)为原料制备了聚合物凝胶电解质, 用电化学阻抗谱(EIS)研究了聚合物凝胶电解质中聚合物基质的结构与组成对准固态染料敏化太阳能电池(DSSCs)光伏性能的影响. 不同交联剂用量、不同HEMA用量的P(HEMA-NVP)共聚物及不同MMA用量的P(MMA-NVP)吸收液态电解质后分别形成HGelI、HGelII、MGel凝胶电解质. 结果发现, 随共聚物P(HEMA-NVP)中交联剂由0.1%(w, 下同)增大到0.6%时, 形成的HGelI 组装的DSSCs的光电转化效率(η)先增大后降低, 交联剂用量为0.4%时, DSSCs的η为最大, 为5.54%(光强100 mW·cm^-2). 同时, 比较HGelII 系列和MGel 系列DSSCs的光电性能参数发现, 含有羟基的HGel 系列的η要高于MGel 系列, 而后者的开路电压(V_oc)值高于前者. 在HGelII 系列中, HEMA含量为60%(w)时, DSSCs的η最高. 电化学阻抗谱分析表明共聚物中交联结构的不同影响了电池内部的界面阻抗及离子的传输, 引入羟基有利于降低界面阻抗. 通过调整共聚物中交联剂用量和羟基含量可改善DSSCs的光伏性能.     

Highly stable gel electrolytes for dye solar cells based on chemically engineered polymethacrylic hosts

Four different species of ionically conductive polymers were synthesized and successfully implemented to formulate novel quasi-solid electrolytes for dye solar cells. A power conversion efficiency superior to 85% of the correspondent liquid electrolyte as well as an excellent cell's stability was demonstrated after 500 days of storage.     

The effects of polymer gel electrolyte composition on performance of quasi-solid-state dye-sensitized solar cells

Polymer gel electrolytes based on poly(acrylic acid)-poly(ethylene glycol) (PAA–PEG) hybrid have been prepared and applied to developed quasi-solid-state dye-sensitized solar cells (DSCs). PAA–PEG hybrid was synthesized by polymerization reaction. Quasi-solid-state DSCs were fabricated with synthesized PAA–PEG electrolyte. The effects of alkali iodides LiI, KI, and I₂ concentrations on liquid electrolyte absorbency and ionic conductivity of PAA–PEG were investigated. The evolution of the solar cell parameters with polymer gel electrolyte compositions was revealed. DSCs based on PAA–PEG with optimized KI/I₂ concentrations showed better performances than those with optimized LiI/I₂ concentrations. The electrochemical impedance spectroscopy technique was employed to examine the electron lifetime in the TiO₂ electrode and quantify charge transfer resistances at the TiO₂/dye/electrolyte interface and the counter electrode in the solar cells based on the PAA–PEG hybrid gels. A maximum conversion efficiency of 4.96% was obtained for DSCs using KI based quasi-solid electrolyte under 100 mW cm⁻². Our work suggests that KI can be the promising alkali metal iodide for improving the performance of PAA–PEG hybrid gel DSCs.