CH3NH3PbI3形貌对钙钛矿电池性能的影响研究

研究不同CH_3NH_3bI_3钙钛矿形貌对钙钛矿太阳电池光伏性能的影响。采用传统的一步法和三步法制备出不同CH_3NH_3bI_3钙钛矿形貌对电池的光伏性能有重要影响。结果表明,钙钛矿在TiO+2电子传输材料表面的覆盖程度对钙钛矿太阳电池的开路电压和填充因子有重要影响。三步法制备的钙钛矿太阳电池获得1.03 V的开路电压和20.25 mA/cm~2短路电流密度,而一步法只有0.72 V和18.42 mA/cm~2。同时,三步法制备的钙钛矿太阳电池的填充因子高达77.2%,相比一步法只有64.5%。2种方法制备的钙钛矿电池分别获得17.36%和8.55%的光电转换效率。利用电化学阻抗谱进一步分析一步法和三步法制备的钙钛矿太阳电池的内部电荷复合动力学过程,解释三步法制备的钙钛矿太阳电池获得更高开路电压的原因。     

钙钛矿型多晶薄膜太阳电池(2)

<正>2013年,瑞士联邦理工学院Graetzel M小组提出用溶液旋涂两步法,依次在纳米多孔Ti O2薄膜上沉积Pb I2和CH3NH3I,以合成钙钛矿CH3NH3Pb I3多晶薄膜,显著改善了薄膜的均匀性,使电池效率跃升到15.0%[5]。同年,英国牛津大学物理系Liu Mingzhen等[6]采用双源共蒸发技术制备CH3NH3Pb I3-xClx     

染料敏化太阳电池中TiO_2薄膜微结构相关动力学研究

采用溶胶-凝胶法制备尺寸大小20nm和300nm的两种TiO2颗粒,二者以不同比例掺杂制备纳米多孔薄膜并应用于染料敏化太阳电池(DSC)中。采用强度调制光电流谱(IMPS)和强度调制光电压谱(IMVS)技术研究薄膜微结构变化对电子传输动力学过程的影响,进而分析大颗粒掺杂对电池性能影响的内在原因。结果表明,TiO2大颗粒作为光散射中心使光程增加可有效增大光强,但掺杂比例与染料吸附量存在竞争进而影响光吸收,研究表明:掺杂20wt%大颗粒纳米薄膜制备的DSC具有最佳性能,相比未掺杂的DSC,掺杂20wt%大颗粒的DSC短路电流Jsc从10.99mA/cm2增加到12.04mA/cm2,光电转换效率η增大8.2%。随TiO2大颗粒掺杂比例增大,电子传输时间τd减小。     

连续旋涂提高钙钛矿太阳电池开路电压的研究

在钙钛矿太阳电池的制作过程中,通过改善旋涂方法和条件,可大大提高钙钛矿吸收层的结晶性以及太阳电池的光电转换性能。与常规的一次性旋涂方法相比,采用连续二次旋涂方法制作的钙钛矿薄膜更加致密,结晶性明显提高。旋涂时前驱液和衬底的温度会影响钙钛矿层的晶体结构,温度为60℃时,钙钛矿的平均晶粒尺寸约为500 nm,且晶粒之间致密排列,导致光学带隙增加。采用连续二次旋涂方法,在加热温度为60℃时制作的钙钛矿太阳电池的光电转换效率达到14.7%,其中短路电流密度、开路电压和填充因子分别为18.9 m A/cm~2、1.13 V和69%。与常规钙钛矿太阳电池相比,开路电压提高约100 m V。依据暗态J-V测试结果,二次旋涂工艺条件下,该光伏器件的反向饱和电流密度约为10~(-5)m A/cm~2,比一次旋涂工艺降低3个数量级。     

碘三离子后处理对钙钛矿太阳电池的影响研究

采用碘三离子(I₃^-)作为提升钙钛矿太阳电池性能的界面修饰材料，对钙钛矿体相及上层空穴传输材料的接触界面进行修饰和改性，钝化光活性层上表面缺陷，以优化光电转换器件的转换效率。由反溶剂法和后处理的形式，制备平面异质结电池，运用该界面钝化策略改善后的器件效率达到18.9%，且电池的稳定性也得到增强，600 h后仅有5%的性能衰减。通过物相和光电性质等表征与测试，系统地研究电池的形貌及性能参数，探究不同浓度的I₃^-对器件性能的影响作用和机理。研究发现，该缺陷钝化策略对钙钛矿膜层进行处理后，能有效改善钙钛矿材料的结晶性，减少其表面陷阱态缺陷，降低钙钛矿与空穴传输层的载流子界面传输势垒，且I₃^-与钙钛矿能形成钝化层，起到隔绝水氧的作用，使其稳定性得到改善。     

染料敏化太阳电池中电子传输性能

通过检测染料敏化TiO2纳米晶太阳电池中TiO2膜厚度和入射光的强度对电池光电转换性能的影响来研究电池中电子的传输性能。结果表明：TiO2膜厚度和入射光强度对电池性能有很大的影响。当TiO2膜厚度增大时，电池的短路电流(Isc)加大，而填充因子(ff)下降，开路电压(Voc)先上升后下降，电池的单色光光电转化效率(IPCE)增大；当光强度加大时，电池的短路电流和开路电压均增加，但是电池的填充因子降低。并用UV-Vis等手段表征了染料RuL2(SCN)2。     

低压气相辅助溶液法制备无铅铋基钙钛矿太阳电池的研究

采用低压气相辅助溶液法制备MA_3Bi_2I_9钙钛矿太阳电池,制备了晶粒大小为300 nm,表面致密且粗糙低的MA_3Bi_2I_9钙钛矿薄膜,其吸收边位置在598 nm,光学吸收带隙为2.07 eV。还通过对一步溶液法、两步溶液法和低压气相辅助溶液法3种方法制备的MA_3Bi_2I_9钙钛矿太阳电池进行对比发现,与其他2种方法制备的钙钛矿薄膜呈现二维片状晶体结构不同,通过低压气相辅助溶液法制备的MA_3Bi_2I_9钙钛矿薄膜更为致密,晶粒大小均匀。通过研究发现,该薄膜均匀的表面形貌有效抑制了薄膜内部载流子的复合,载流子瞬态荧光寿命由7.17 ns提升至8.81 ns,制备的钙钛矿太阳电池效率为0.178%,比一步溶液法和两步溶液法制备的太阳电池效率提升了2倍。     

钙钛矿太阳电池载流子传输-复合模型研究

通过对所制备的钙钛矿太阳电池进行交流阻抗测试,比较钙钛矿电池载流子扩散长度、载流子寿命、内部电阻及电容等参数,得出在钙钛矿太阳电池中载流子在空穴传输层扩散的特征频率约为2μs~(-1),载流子传输过程快慢顺序依次为:载流子在空穴传输层的传输、钙钛矿薄膜中的传输。另外还得出载流子在钙钛矿薄膜中的复合阻抗是构成电池总阻抗的主要部分,其值远大于空穴传输层的阻抗,约为空穴传输层的15倍。     

基于宽带隙P-I-N结构的高效有机小分子太阳电池

研制了一种采用混合的P-I-N异质结结构、基于混合ZnPc和C60的有机小分子太阳电池。该有机太阳电池光电转换由ZnPc和C60异质结混合成膜完成,电子和空穴分别通过n掺杂和p掺杂的宽带有机层传输至阴极和阳极,不同掺杂的电子或空穴传输层由精确控制两种有机小分子的蒸镀速率来实现;其中空穴传输层采用N,N,N’,N-’Tetrakis(4-methoxyphenyl)-benzidine(MeO-TPD)为基底材料和Tetrafluoro-tetracyano-quinodimethane(F4-TCNQ)为掺杂材料,电子传输层采用C60为基底材料,而掺杂材料为Leuco Crystal violet(LCV)。实验发现:可以通过改变光电转换层和电子传输层的厚度,优化器件的结构;与未掺杂的有机薄膜相比,掺杂的宽带有机传输层导电率提高了3~4个数量级,并且它们几乎不吸收太阳光;电子传输层的厚度直接影响太阳电池的转换效率,这与薄膜光学的预期结果相符;当增大光电转换层的厚度,不仅增加了光吸收,同时电子空穴的复合率也随之增加,因此器件的填充因子降低。实验结果表明:该有机太阳电池的光电转换效率可达2.4%。     

染料敏化太阳电池基底的选择和工艺分析

染料敏化太阳电池是由透明导电玻璃、纳米晶TiO2多孔薄膜、电解质溶液以及镀Pt对电极构成的"三明治"式结构.染料敏化太阳电池基底的选择对DSSC电池的光电性能和成本具有重要研究价值和实用意义.本文对当前染料敏化太阳电池研究领域常用基底进行了比较和工艺分析.     

酞菁和N3染料协同敏化对纳米TiO2薄膜光电池性能的影响

采用酞菁染料和N3染料共同对纳米TiO2薄膜进行光敏化处理,并将染色后的纳米TiO2薄膜组装成光电池。用场发射SEM、XRD对制备的纳米TiO2薄膜进行表征,用UV-Vis紫外可见光仪对染色处理后的纳米TiO2薄膜的吸光度进行测量。实验数据表明,与N3染料相比,经两种染料共同敏化后的纳米TiO2薄膜可增加对波长大于570 nm以上光能量的吸收,但这种薄膜对模拟太阳光主波长范围内的光吸收下降了,因而造成两种染料组合敏化电池的短路光电流密度下降了4.73mA/cm2,开路电压减少了60mV。     

喷涂法制备混合阳离子钙钛矿太阳电池

采用热基底喷涂法分别制备了FA_0.85MA_0.15PbI₃和(FAPbI₃)_0.85(MAPbBr₃)_0.15两种混合阳离子钙钛矿薄膜,对两种薄膜进行了扫描电镜（SEM）、X-射线衍射（XRD）、紫外-可见光吸收光谱（UV-Vis）测试表征。结果表明,该方法制备的混合阳离子钙钛矿薄膜平整致密,FA_0.85MA_0.15PbI₃结晶性更好,并且吸收带边和吸收强度更大。将两种薄膜组装成平板太阳能电池,对电池的光电性能和稳定性进行了分析。结果表明,FA_0.85MA_0.15PbI₃ PSCs光电转换效率为13.21%,(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs光电转换效率为12.08%,并且(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs在放置80 d后,性能基本无变化,表明喷涂法制备(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs具有较好的稳定性。     

光电致变色薄膜及其器件

光电致变色器件(Photoelectrochromic device)由染料电池和WO3电致变色薄膜电极组成。本研究采用溶胶一凝胶法分别制备WO3和TiO2纳米薄膜，并组装成光电致变色器件，对不同热处理和薄膜厚度下的器件的光电致变色性能进行测试分析。试验表明用提拉法制成的WO3薄膜和用旋涂法及丝网印刷制成的TiO2薄膜，都具有较好的成膜性，并且由其组装成的器件具有良好的光电致变色效果。     

Al2O3修饰层对抑制CdSe量子点敏化太阳电池界面电子复合的研究

量子点敏化纳米TiO2太阳电池（QDSSCs）因成本低廉,近年来得到广泛关注。但是其光电转换效率仍然较低,其中主要的原因是量子点表面缺陷密度高,表面与界面电子复合严重。本文以Al2O3为纳米TiO2/CdSe QDs的界面修饰层,采用暗态下的电化学阻抗谱（EIS）以及开路电压衰减谱考察了Al2O3对抑制电子复合所起的作用,并简析了其中的作用机理。研究结果表明,TiO2表面修饰Al2O3后,其导带边上移;此外,TiO2/QDs界面缺陷态降低,界面电子复合降低,使器件的短路电流、开路电压以及填充因子提高,光电转换性能得到改善。     

Enhancing the short-circuit current and efficiency of organic solar cells using MoO3 and CuPc as buffer layers

Efficient bulk-heterojunction (BHJ) (regioregular poly (3-hexylthiophene) (P3HT): (6, 6)-phenyl C₆₁ butyric acid methyl ester (PCBM)) solar cells were fabricated with molybdenum trioxide (MoO₃) and copper phthalocyanine (CuPc) as buffer layers. The insertion of MoO₃ layer was found to be critical to the device performance, effectively extracting holes to prevent the exciton quenching and reducing the interfacial resistance because of alignment of energy levels. The introduction of CuPc buffer layer was observed to be ameliorative for device performance, further enlarging the visible absorption spectra range of the devices. The effect of the MoO₃ and CuPc layer thickness on device performance was studied. The optimized thickness was achieved when MoO₃ layer was 12 nm and CuPc layer was 6 nm, resulting in optimized power conversion efficiency (PCE) of 3.76% under AM1.5G 100 mW/cm² illumination.     

太阳光TiO_2多孔纳米薄膜光催化降解有机磷农药的研究

锐钛矿型 Ti O2 多孔纳米薄膜可以从含聚乙二醇的钛醇盐溶胶前驱体中通过浸渍提拉法制备 ;涂层的形貌如孔的大小和孔的分布可以通过聚乙二醇的加入量来控制 ,当聚乙二醇的加入量为 0— 2 .0 g时 ,孔径大小在 0— 40 0 nm范围内变化。可见光透过光谱分析表明 :随着 Ti O2 薄膜中孔径增大 ,光的散射增强 ,透光率减小 ,该 Ti O2 镀膜玻璃对于紫外线具有吸收作用。有机磷农药水溶液的太阳光催化降解实验表明 :在 Ti O2 薄膜中引入气孔增强了光催化活性 ,孔的大小和薄膜厚度对光解率有显著的影响。当孔径大小为 1 0 0— 2 0 0 nm,镀膜次数为 1 0— 1 5次时 ,Ti O2 薄膜显示光催化效率高。     

ITO/Metal/ITO叠层电极中Cu/Ag对钙钛矿太阳电池电极性能的影响

研究ITO/Metal/ITO（IMI）电极中金属层Cu和Ag及其厚度对电极光电性能的影响,结合霍尔测试、紫外分光光度计、原子力显微镜等分析金属层材料和厚度对IMI电极光电性能以及形貌的影响。通过优化金属层厚度,获得方阻分别为11.2 Ω/□和14.5 Ω/□且400~800 nm波长范围内平均透过率分别为93.9%和86.5%的ITO/Ag/ITO和ITO/Cu/ITO电极。将IAI和ICI电极作为正面电极应用于钙钛矿太阳电池,太阳电池的填充因子从62.5%提升至78.0%。IMI在短波段的较大反射率会导致电池短路电流密度低1~2 mA/cm²。当Cu层和Ag层的厚度分别为7.4 nm和6.4 nm时,钙钛矿太阳电池的效率达到最佳。     

UV light protection through TiO2 blocking layers for inverted organic solar cells

Fully organic solar cells (OSCs) based on polymers and fullerenes have attracted remarkable interest during the last decade and high power conversion efficiencies (PCEs) beyond 8% have been realized. However, air stability of these cells remains poor. The conventional geometry of OSCs utilizes strongly oxidizing metal top contacts like Al or Ca. These metals are easily oxidized in air resulting in rapid decrease of PCE if cells are not perfectly encapsulated. Using a thin electron-selective hole-blocking bottom layer like TiO₂ enables fabrication of solar cells in a so-called inverted geometry. In this geometry, noble metals like Ag or Au can be used as top contacts, which are less sensitive to ambient oxygen. Thus, air-stability of these inverted solar cells is significantly improved. In this study we investigate inverted polythiophene-methanofullerene solar cells. We find significant influence of the TiO₂ layer thickness on light absorption and illumination stability of the solar cells, as well as the trap filling by photoinduced carriers. Even though TiO₂ layers as thick as 500 nm seem not to be detrimental for charge transport, light intensity losses limit the device performance. In turn, illumination stability is better for thicker TiO₂ layers, which can serve as UV filters and protect the photoactive materials from degradation, when compared to thin TiO₂ layers. Considering these different effects we state that a thickness of 100 nm is the optimization of the TiO₂ layer.     

Novel carbon‐based material for perovskite solar cells back‐contact

Perovskite solar cells are one of the most promising photovoltaic technology, presenting the fastest power conversion efficiency (PCE) growth from 3.8 % to 24.2 % in just 10 years. However, there are still challenges hindering its commercialization such as the expensive back‐contact made of gold. Carbon‐based materials, mainly carbon pastes made of carbon black and graphite, have already proven to be good candidates as back‐contacts because of their features such as low cost, high conductivity, and high stability. In this work, the replacement of gold back‐contact by a carbon paper with a microporous layer coated with a PEDOT:PSS dispersion is reported. To the best of the author's knowledge, this material has never been reported for perovskite solar cells. A PCE of 9.22 % was obtained, representing 62 % of the PCE obtained for the same cell but with a gold back‐contact.     

Bulk and contact resistance in P3HT:PCBM heterojunction solar cells

In this paper, the series resistance of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells (OSC) has been studied. The series resistance of thermal annealed and un-annealed devices with different active layer thicknesses was measured. The series resistance of the organic solar cells consists of the bulk resistance of the active layer itself and the specific contact resistance between the active layer and the electrode. The bulk resistance and contact resistance were extracted from the measured series resistance using the vertical transmission line model (TLM) method. By fabricating solar cell devices with different active layer thicknesses, a relationship of the series resistance with thickness was established from which bulk and contact resistances were derived. We have also found that thermal annealing helps reduce both contact resistance and bulk resistance significantly; the contact resistance dropped by a factor of 2, while the bulk resistance decreased by a factor of 8. Results have shown that for an annealed P3HT:PCBM device that has an active layer thickness of 85 nm (optimum thickness for high efficiency), 17% of the total series resistance was due to the contact resistance, and bulk resistance contributed the rest 83%. The bulk resistance value for thermal annealed organic solar cell device with an active area of 0.1 cm² was found to be 150 Ω, and the measured specific contact resistance was 3.1 Ω cm². The measured bulk and contact resistance values are much higher as compared to the high efficiency silicon solar cells. Bulk resistance and contact resistance need to be further decreased in order to achieve higher organic solar cell efficiency.