酞菁铜/氟代苝酰亚胺异质结性能研究

合成一种氟代n型有机半导体材料2,5-二氟代苯基苝酰亚胺(D25DFPP),制备CuPc/D25DFPP异质结,研究异质结的结构和性能,并将其引入ITO/PEDOT:PSS/CuPc/D25DFPP/Al结构光伏器件。结果表明,D25DFPP与CuPc的紫外-可见吸收光谱有较好的光吸收互补特性。通过紫外光电子能谱(UPS)研究CuPc/D25DFPP异质结的电子结构,发现在两者的界面处同时存在能带弯曲和界面偶极作用,异质结中发生较强的电荷转移,并且两者能级匹配。异质结在120℃下退火后有较大的晶粒和较强的荧光猝灭,使得退火后光伏器件的光电转换效率比未退火时提高1倍以上,达到0.82%,显示在光电转换领域有着潜在的应用前景。     

PEDOT:PSS对PEDOT:PSS/Si杂化太阳电池性能影响的研究

聚合物poly(3,4-ethylenedioxythiophene):polystyrene sulfonate(PEDOT:PSS)是一种具有高电导率和良好透过性的p型半导体材料。PEDOT:PSS/Si杂化太阳电池由于具有较低的工艺温度,且工艺简单而具有一定的前景。在这种杂化太阳电池结构中,PEDOT:PSS的光学、电学性质对器件性能有重要影响。分别从PEDOT:PSS退火工艺、溶液二次掺杂(二甲基亚砜)的含量以及PEDOT:PSS薄膜厚度3个方面对薄膜的光、电特性以及器件性能的影响进行研究,并优化相关工艺。根据这些优化的参数,最终得到6.63%的太阳电池转化效率(太阳电池面积为2.25 cm^2)。     

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%。     

镁钙铝合金阴极小分子有机太阳能电池

为了提高小分子有机太阳能电池电极对载流子的收集能力,并提高激子的分离效率,文章采用不同比例的Mg/Ca/Al合金及纯Al分别制备了结构为ITO/CuPc(20 nm)/C60∶CuPc(10 nm)/C60(30 nm)/BPhen(10nm)/Mg(x%)∶Ca∶Al(100 nm)和ITO/CuPc(20 nm)/C60∶CuPc(10 nm)/C60(30 nm)/BPhen(10 nm)/Al(100 nm)2种(共5组)有机光伏器件(OPV),并对这5组有机光伏器件进行对比分析,以此来研究阴极材料组成对有机光伏器件性能的影响,并获得性能更优的有机光伏器件。研究结果表明,与纯Al阴极相比,Mg/Ca/Al合金阴极可以提高电极对载流子的收集效率,有助于提高有机光伏器件的光电转换效率,并且当合金阴极中Mg的质量分数为20%时,有机光伏器件性能最优,在光功率密度为100 m W/cm~2的模拟光源AM1.5G照射下,该有机光伏器件的开路电压为0.34 V,短路电流密度为6.90 m A/cm~2,光电转换效率为0.91%,光电转换效率比同结构纯Al阴极器件提高了88.24%。     

碘化铅残留对钙钛矿太阳电池性能影响

通过对一步法和两步法制备的钙钛矿电池器件的光电性能进行研究,发现2种方法制备的太阳电池主要性能参数有明显差异。一步法制备的器件有更大的短路电流密度(Jsc)和更高的填充因子(FF),两步法制备的器件有更高的开路电压(Voc)。通过电容-电压(C-V)测量、外量子效率以及开路电压随光强变化,发现两步法中PbI_2对器件性能的影响。PbI_2在聚3,4-乙撑二氧噻吩:聚苯乙烯磺酸盐(PEDOT:PSS)和钙钛矿之间形成空穴阻挡层,有利于开路电压的提高,但对空穴传输和载流子收集有不利的影响。     

聚乙二醇对PTB7：PC70BM太阳电池的影响

对以PTB7:PC_(70)BM为体系的聚合物太阳电池(BHJ)的阳极修饰层PEDOT:PSS中掺杂聚乙二醇(PEG)的方法进行研究,发现阳极修饰层中掺杂不同浓度的PEG后,器件的各项性能均有所提升。通过电流电压(I-V)测试、电容-电压(C-V)测试、外量子效率(EQE)测试、及不同浓度PEG下PEDOT:PSS的电导率的测量发现,在PEDOT:PSS中掺杂体积比为1%的PEG时,太阳电池器件的填充因子(FF)、短路电流(J_(sc))等有明显提升。其光电转换效率从5.88%升至6.48%,比基础器件提高10%。     

基于三角形光栅结构的薄膜晶硅/PEDOT：PSS异质结太阳电池的陷光设计

针对薄膜硅的光学管理问题,通过有限元方法求解麦克斯韦基本方程组,研究基于一维三角形光栅结构对电池的光吸收率、光电流密度(Jph)和电场强度分布的影响,设计并优化适合2μm硅/PEDOT:PSS系统的双面一维三角形光栅结构,有效提升薄膜硅的光学吸收,并能与PEDOT:PSS形成优异的异质结,基于此结构的薄膜硅/PEDOT:PSS异质结太阳电池的效率可超过15%,展现了高效柔性薄膜硅/PEDOT:PSS HSCs的可行性。     

退火对活性层P3HT:PCBM性能的影响

采用匀胶机旋涂成膜的方法在手套箱中制备了P3HT:PCBM薄膜,详细研究了退火处理对薄膜的吸收、晶体结构以及表面形貌的影响,并全面阐述了它们之间的联系。结果发现退火后薄膜的吸收增强,吸收峰的峰位有所红移,通过XRD测试研究表明是因为薄膜出现了不同程度的晶化,主要是P3HT发生了部分晶化。对表面形貌进一步研究发现退火后薄膜的表面粗糙度有所增加,并形成了一定清晰可见的互穿网络,薄膜发生品化,使薄膜性能得到大大改善。将优化得到的材料用于太阳电池中,电池结构为glass/ITO/PEDOT:PSS/P3HT:PCBM/Al,在AM1.5,100mW/cm~2条件下测试获得电池效率1.41%。     

ITO Etched by Photolithography Used in the Fabrication of Flexible Organic Solar Cells with PET Substrates

In this study, the authors have shown the power conversion efficiency of flexible organic solar cells. The structure of the device is PET/ITO/PEDOT： PSS/P3HT： PCBM/AI. P3HT （poly-3-hexylthiophene）. It was used as an electron donor, PCBM （[6, 6]-phenyl C6 l-butyric acid methyl ester） as an electron acceptor and PEDOT： PSS used as a HIL （hole injection layer）. These materials were deposited by spin coating method on the flexible substrates. Photolithography method is used to etch ITO. The electrical parameters of the fabricated cells were investigated by means of J （V）, FF （fill factor）, the efficiency （r/）, photocurrent and IPCE measurement. It was observed that 45% of the absorbed photons are converted into current. The results obtained using etching technology by photolithography is better than that obtained in the clean room.     

埋栅TCO薄膜的制备及在太阳电池上的应用

提出新型金属埋栅结构来改良透明导电氧化物薄膜(TCO)的光电性能,并分别采用AZO和ITO这2种TCO材料制备和对比3类薄膜(单层TCO薄膜、TCO/金属薄膜/TCO以及TCO/金属栅线/TCO三明治结构的薄膜)的光学和电学性能。本文制备的新型叠层AZO/Mg栅线/AZO和ITO/Ag栅线/ITO结构在300～1200 nm范围内光学透过率保持约在85%,方阻分别降低至1.94和91 Ω/□。将ITO/Ag栅线/ITO作为TCO用在n-CdS/p-Si异质结电池上取得了 9.31%的效率,相比单层ITO的电池转换效率提高了 6.03%。该工作为低方阻、高光学透过率TCO的制备提供了一种行之有效的思路,在光电子器件上也具有一定的应用前景。     

Enhancement of short current density in polymer solar cells with phthalocyanine tin (IV) dichloride as interfacial layer

The effect of n-type phthalocyanine tin (IV) dichloride (SnCl₂Pc) as cathode interfacial layer on the performance of poly[2-methoxy,5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells (ITO/PEDOT:PSS/MEH-PPV:PCBM/SnCl₂Pc/LiF/Al) is investigated. Our results show that the integration of SnCl₂Pc into the solar cell not only enhances the exciton dissociation efficiency due to the formation of additional MEH-PPV/SnCl₂Pc exciton dissociation junction, but also improves the electron transport and collection due to the step-like electron injection barrier to cathode caused by SnCl₂Pc interlayer. The incorporation of 6 nm thick SnCl₂Pc interlayer leads to 15.7% improvement of the short circuit current density (J_SC), which in turn results in 15.2% improvement of power conversion efficiency (η) up to 2.49%. The results suggest that the employment of an n-type organic semiconductor like SnCl₂Pc as an interlayer is a promising strategy to improve the device performance of polymer solar cells.     

Improved the efficiency of small molecule organic solar cell by double anode buffer layers

Small molecule organic solar cell with an optimized hybrid planar-mixed molecular heterojunction (PM-HJ) structure of indium tin oxide (ITO)/ poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) doped with 4 wt% sorbitol/ pentacene (2 nm)/ copper phthalocyanine (CuPc) (10 nm)/ CuPc: C₆₀ mixed (20 nm)/ fullerene (C₆₀) (20 nm)/ bathocuproine (BCP) (10 nm)/Al was fabricated. PEDOT: PSS layer doped with 4 wt% sorbitol and pentacene layer were used as interlayers between the ITO anode and CuPc layer to help the hole transport. And then the short-circuit current (J_sc) of solar cell was enhanced by inserting both the PEDOT: PSS (4 wt% sorbitol) and the pentacene, resulting in a 400% enhancement in power conversion efficiency (PCE). The maximum PCE of 3.9% was obtained under 1sun standard AM1.5G solar illumination of 100 mW/cm².     

Comparison of normal and inverse poly(3-hexylthiophene)/fullerene solar cell architectures

Polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and ([6,6]-phenyl-C61-butyric acid methyl ester) (PCBM) were fabricated with two different architectures (normal and inverse). Normal cells using indium tin oxide (ITO) as anode and Al as cathode were fabricated on polyester foils and illuminated from substrate side. Inverse cells using Ti as cathode and ultrathin Au layer as anode were illuminated from the top side covered by a transparent Au contact. Both Au layer and PET/ITO show comparable transmission in the spectral range where P3HT absorbs. Inverse cells showed comparable device parameters to normal cell (open circuit voltage 550 mV, short circuit current 6.25 mA/cm², fill factor 0.33 and white light power conversion efficiency 1.12%).     

Synthesis and photovoltaic properties of a star-shaped molecule with triphenylamine as core and benzo[1,2,5]thiadiazol vinylene as arms

A solution-processable and star-shaped molecule 4-((E)-2-(benzo[1,2,5]thiadiazol-4-yl)vinyl)-N,N-bis(4-((E)-2-(benzo[1,2,5]thiadiazol-7-yl)vinyl)phenyl)benzenamine (TPA-BT) has been designed and synthesized by palladium-catalyzed Heck reaction for the application in organic solar cells (OSCs). The molecule possesses a D-A structure with a triphenylamine core (donor unit) linked with three benzo[1,2,5]thiadiazole (acceptor unit) arms through double bonds. TPA-BT film shows a strong absorption peak in the visible wavelength range from 400 to 560 nm, which could be ascribed to the charge transfer band of the D-A structure of the molecule. The bulk-heterojunction OSCs with the device structure of ITO/PEDOT:PSS/TPA-BT:PCBM/Ca/Al (or Ba/Al) were fabricated by spin-coating the blend solution of TPA-BT and PCBM (1:3, w/w), in which TPA-BT was used as donor and PCBM as acceptor materials. The devices show a high open circuit voltage of ca. 0.9 V and a power conversion efficiency of 0.61%, under the illumination of AM 1.5, 100 mW/cm². The results indicate that TPA-BT is a promising solution-processable organic photovoltaic material.     

Influence of doped PEDOT:PSS on the performance of polymer solar cells

The influence of anode buffer layers of doped poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) on the performance of solar cells made from blends of poly(3-hexylthiophene) and [6,6]-phenyl-C₆₁-buytyric acid methyl ester has been investigated. Different concentration of ethylene glycol were added into the PEDOT:PSS solution to increase its conductivity. The surface roughness of the doped PEDOT:PSS film was changed, which was examined by atomic force microscopy. The best doped device with a power conversion efficiency of 4.39% as compared to 3.41% for the pristine device has been achieved. The enhanced PEDOT:PSS conductivity improved the short circuit current and fill factor of the doped device. The almost constant open circuit voltage indicated the well-established ohmic contact between the anode and active layer irrespective of the doping of the PEDOT:PSS. The changed surface roughness of the doped PEDOT:PSS film did not correlate with the morphology of the consequent active layer and the resultant device performance.     

Hybrid inverted organic photovoltaic cells based on nanoporous TiO2 films and organic small molecules

Solar cells based on nanoporous TiO₂ films with an inverted structure of indium tin oxide (ITO)/TiO₂/copper phthalocyanine (CuPc):fullerene (C₆₀)/CuPc/poly(3,4-oxyethyleneoxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Au were fabricated. The best overall photovoltaic performance undergoing a series of device optimization was achieved with the device of ITO/dense TiO₂ (30 nm)/nanoporous TiO₂ (130 nm)/C₆₀:CuPc (1:6 weight) (20 nm)/CuPc (20 nm)/PEDOT:PSS (50 nm)/Au (30 nm). The device using the nanoporous TiO₂ films has better photovoltaic properties compared to those using dense TiO₂ films. Higher photovoltaic performances were obtained by introducing a coevaporated layer of C₆₀:CuPc between TiO₂ and CuPc. The stability of inverted structure was better than that of the normal device, which gives a promising way for fabrication of solar cells with improved stability.     

Improving power conversion efficiency in polythiophene/fullerene-based bulk heterojunction solar cells

In the present work, we have studied photovoltaic devices fabricated from a blend of regioregular poly (3-hexlthiophene) (P3HT) and Buckminster fullerene. The solvent and composite ratio have been selected to obtain best morphology and minimum degradation. Buffer layers of poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) at the anode and of LiF at the cathode were used to improve the device performance. It was further found that post-annealing of the devices for an optimum duration and temperature improves the solar cells, and the power conversion efficiency of the devices increases to 2.1% at AM1.5. Though the efficiency using [6,6]-phenyl C60 butyric acid methyl ester (PCBM) as the composite acceptor instead of C₆₀ can be higher, it was not used because of its very high cost as compared to C₆₀.     

Synthesis and characterization of a novel fullerene derivative for use in organic solar cells

A novel fullerene derivative with an N-hexylphenothiazine moiety, PTZ-C_60, was synthesized and characterized. The new synthesized fullerene showed good solubility in common organic solvents such as toluene, chlorobenzene and 1, 2 dichlorobenzene. The synthetic product PTZ-C₆₀ was characterized by ¹H and ¹³C NMR, FT-IR and UV-vis spectroscopy. Photovoltaic devices were fabricated using the new fullerene derivative as the electron acceptor and P3HT as the electron donor. The configuration of the device was as follows: ITO/PEDOT:PSS/active layer/LiF/Al. The weight ratios of the electron donor to the acceptor in the active layer were 1:0.5, 1:0.7, and 1:1. The open-circuit voltage (V_oc) of the fabricated devices was found to be higher than that of devices based on C₆₀ because the LUMO energy level of the new fullerene derivative was higher than that of C₆₀. Further, the power conversion efficiency (PCE) of these devices was observed to be high when annealing was carried out at 150 °C for 5 min and the thickness of the active layer was 80 nm. The maximum V_oc, short-circuit current density, and PCE of the best device were 0.608 V, 4.393 mA/cm², and 1.29%, respectively.     

Degradation of organic solar cells due to air exposure

We present a study of dark air-exposure degradation of organic solar cells based on photoactive blends of the conjugated polymer, poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) with [6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM). Photovoltaic devices were fabricated on indium tin oxide (ITO) glass with or without a layer of poly (3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS), and were studied without encapsulation. Photovoltaic performance characteristics were measured as a function of time for different ambient conditions (under white light irradiation and in the dark, and under air, dry oxygen and humid nitrogen atmospheres). It was found that a key cause of degradation under air exposure is light independent and results from water adsorption by the hygroscopic PEDOT:PSS layer. Measurements of the charge mobility and hole injection after air exposure showed that the degradation increases the resistance of the PEDOT:PSS/blend layer interface.     

ITO-free low-cost organic solar cells with highly conductive poly(3,4 ethylenedioxythiophene): p-toluene sulfonate anodes

Indium tin oxide (ITO)-free organic solar cells were fabricated with highly conductive and transparent tosylate-doped poly(3,4-ethylenedioxythiophene: p-toluene sulfonate) (PEDOT:PTS) anodes of various thicknesses that were prepared by the vapor-phase oxidative polymerization of EDOT using Fe(PTS)₃ as an oxidant. Both solution-processable layers - PEDOT:PSS and photoactive P3HT:PCBM - were spin coated. The anodes transmittance and conductivity varied with thickness. Power conversion efficiency was maximized at 1.4%. The ITO-free organic solar cells photovoltaic characteristics are qualitatively compared with those of ITO-based organic solar cells to explore the possibility of replacing costly, vacuum-deposited ITO with highly conductive, patterned polymer films fabricated by inexpensive vapor-phase polymerization.