Improving efficiency of inverted perovskite solar cells via ethanolamine-doped PEDOT:PSS as hole transport layer

In order to fabricate high-performance inverted perovskite solar cells (PeSCs), an appropriate hole transport layer (HTL) is essential since it will affect the hole extraction at perovskite/HTL interface and determine the crystallization quality of the subsequent perovskite films. Herein, a facile and simple method is developed by adding ethanolamine (ETA) into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as HTL. The doping of a low-concentration ETA can efficiently modify the electrical properties of the PEDOT:PSS film and lower the highest occupied molecular orbital (HOMO) level, which is more suitable for the hole extraction from the perovskite to HTL. Besides, ETA-doped PEDOT:PSS will create a perovskite film with larger grain size and higher crystallinity. Hence, the results show that the open-circuit voltage of the device increases from 0.99 V to 1.06 V, and the corresponding power conversion efficiency (PCE) increases from 14.68% to 19.16%. The alkaline nature of ethanolamine greatly neutralizes the acidity of PEDOT:PSS, and plays a role in protecting the anode, leading the stability of the devices to be improved significantly. After being stored for 2000 h, the PCE of ETA-doped PEDOT:PSS devices can maintain 84.2% of the initial value, which is much higher than 67.1% of undoped devices.     

掺杂PEDOT ∶PSS对聚合物太阳能电池性能影响的研究

研究了掺杂后poly(3,4-ethylene dioxythiophene):poly(styrenesulphonic acid)(PEDOT ∶PSS)电导率的变化以及掺杂PEDOT ∶PSS薄膜对聚合物太阳能电池器件性能的影响. 实验发现,向PEDOT ∶PSS中掺入极性溶剂二甲基亚砜(DMSO)明显提高了薄膜的电导率,掺杂后的电导率最大值达到1.25 S/cm,比未掺杂时提高了3个数量级. 将掺杂的PEDOT ∶PSS薄膜作为缓冲层应用于聚合物电池 (ITO/PEDOT ∶PSS/P3HT ∶PCBM/LiF/Al) 中,发现高电导率的PEDOT ∶PSS降低了器件的串联电阻,增加了器件的短路电流,从而提高了器件的性能. 最好的聚合物太阳能电池在100 mW/cm²的光照下,开路电压(V_oc)为0.63 V,短路电流密度(J_sc)为11.09 mA·cm^-2,填充因子(FF)为63.7%,能量转换效率(η)达到4.45%. 关键词： PEDOT ∶PSS 电导率 聚合物太阳能电池 能量转换效率     

Enhancing light absorption for organic solar cells using front ITO nanograting and back ultrathin Al layer

To address the discrepancy between carrier collection and light absorption of organic solar cells caused by the limited carrier mobility and optical absorption coefficient for the normally employed organic photoactive layers, a light management structure composed of a front indium tin oxide(ITO) nanograting and ultrathin Al layer inserted in between the photoactive layer and the electron transport layer(ETL) is introduced. Owing to the antireflection and light scattering induced by the ITO nanograting and the suppression of light absorption in the ETL by the inserted Al layer, the light absorption of the photoactive layer is significantly enhanced in a spectral range from 400 nm to 650 nm that also covers the main energy region of solar irradiation for the normally employed active materials such as the P3HT:PC_(61) BM blend. The simulation results indicate that comparing with the control device with a planar configuration of ITO/PEDOT:PSS/P3HT:PC_(61) BM(80-nm thick)/Zn O/Al, the short-circuit current density and power conversion efficiency of the optimized light management structure can be improved by 32.86% and 34.46%. Moreover, good omnidirectional light management is observed for the proposed device structure. Owing to the fact that the light management structure possesses the simple structure and excellent performance, the exploration of such a structure can be believed to be significant in fabricating the thin film-based optoelectronic devices.     

紫外臭氧处理超薄银修饰ITO电极的高效柔性有机太阳能电池

以紫外臭氧处理超薄Ag复合MoO₃或PEDOT：PSS修饰ITO电极的高效柔性有机太阳能电池。通过优化紫外臭氧处理Ag薄膜的时间,提高了以P3HT：PCBM为有源层的器件的功率转换效率,从1.68%（未经过紫外臭氧处理）提高到2.57%（紫外臭氧处理Ag 1 min）。提高的原因推测是紫外臭氧处理形成了AgO_x薄膜,提高了电荷提取并使器件具有高光学透明度、低串联电阻和优异的表面功函数等一些性能。并且,紫外臭氧处理Ag薄膜与MoO₃或者PEDOT：PSS复合修饰ITO的器件效率分别得到提高,Ag薄膜与MoO₃复合修饰ITO的器件效率从2.02%（PET/ITO/MoO₃）提高到2.97%（PET/ITO/AgO_x/MoO₃）,Ag薄膜与PEDOT：PSS复合修饰ITO的器件效率从2.01%（PET/ITO/PEDOT：PSS）提高到2.93%（PET/ITO/AgO_x/PEDOT：PSS）。此外,以PBDTTT-EFT：PC₇₁BM为有源层的柔性聚合物太阳能电池效率可达6.21%。基于ITO的柔性光电器件效率的提高主要归于ITO被Ag/PEDOT：PSS或Ag/MoO₃修饰后功函数的提高。     

基于改性空穴注入层与复合发光层的高效钙钛矿发光二极管

有机金属卤化钙钛矿作为发射体具有极高的色纯度和极低的成本,但钙钛矿层普遍较差的形貌制约了器件的性能.引入合适的聚合物可有效改善旋涂型钙钛矿薄膜的均匀性.本文引入聚(4-苯乙烯磺酸盐)(PSS)改性的聚(3,4-乙撑二氧噻吩):PSS(PEDOT:PSS)作为空穴注入层(HIL),结合一步旋涂制备的三溴化铅甲基胺(MAPbBr3)和聚(环氧乙烷)(PEO)复合膜作为发光层,制备了高效绿光钙钛矿发光二极管.其中,PSS增加了PEDOT:PSS功函数,降低了其与钙钛矿发光层间的注入势垒;而掺杂PEO的钙钛矿膜致密且均匀,覆盖率可以达到100%.基于改性的空穴注入层和复合发光层,我们最终获得了最大亮度为2476 cd·m^–2、最大电流效率为7.6 cd·A^–1的高效钙钛矿发光二极管.     

体异质结有机太阳能电池性能提高的研究

制备了四种不同结构的有机太阳能电池器件,器件1 ITO/LiF/PEDOT∶PSS/MEH-PPV/C₆₀/Al、器件2 ITO/PEDOT∶PSS/MEH-PPV/C₆₀/Al、器件3 ITO/LiF/PEDOT∶PSS/MEH-PPV∶C₆₀/C₆₀/Al和器件4 ITO/PEDOT∶PSS/MEH-PPV∶C₆₀/C₆₀/Al。测量了它们的电流－电压特性,结果显示在ITO和PEDOT∶PSS之间插入一薄层LiF使得器件性能得到较大提高。其器件1的J_SC和FF比器件2的提高了74%和31%; 器件3的J_SC比器件4的提高了约40%。这主要是由于LiF层有效地抑制了空穴向阳极的传输,并且LiF层在ITO和PEDOT:PSS之间形成了良好的界面特性。因此,这种结构上的改进有效地提高了有机太阳能电池的性能。     

稀释溶剂对PEDOT：PSS薄膜和有机太阳能电池性能的影响

采用喷涂技术制备聚3,4-乙撑二氧噻吩：聚苯乙烯磺酸盐（PEDOT：PSS）有机层薄膜,系统研究了乙醇、去离子水、甲醇、异丙醇和乙二醇等稀释溶剂对PEDOT：PSS薄膜形貌、透过率及导电性能的影响。将PEDOT：PSS薄膜应用于有机太阳能电池器件的制备,研究了不同溶剂对器件性能的影响。实验结果表明：采用乙醇稀释PEDOT：PSS溶液,能有效抑制PEDOT：PSS颗粒团聚,降低薄膜粗糙度,提高薄膜的透过率和导电性。以其制备的太阳能电池器件的能量转换效率明显高于其他溶剂稀释,转换效率为2.66%。     

Polymer solar cells based on a PEDOT:PSS layer spin-coated under the action of an electric field

In the process of fabrication of polymer photovoltaic(PV) devices,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) thin film,acting as an anode buffer layer,is spin-coated under the action of an electric field.The PV devices with a PEDOT:PSS layer spin-coated under the action of a static electric field exhibit improved short-circuit current density(J sc) and power conversion efficiency(PCE).The investigation of morphology shows that the appropriate intensity of the electric field can increase the roughness of the surface of the PEDOT:PSS layer,which results in improved contact between the anode and hole transport layer and thus enhances the J sc of the devices.Chemical analysis is also provided by x-ray photoelectron spectroscopy(XPS) spectra.     

Improvement in performance of organic light-emitting devices by inclusion of multi-wall carbon nanotubes

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was modified by different concentrations of multi-wall carbon nanotubes (MWNTs), and the nanocomposites of PEDOT:PSS and MWNTs were firstly used as hole-injection layer in fabrication of organic light-emitting devices (OLEDs) by using a double-layer structure with hole-injection layer of doped PEDOT:PSS and emitting/electron transport layer of tris(8-hydroxyquinolinato) aluminum (Alq₃). PEDOT:PSS solution doped with MWNTs was spin-coated on clean polyethylene terephthalate (PET) substrate with indium tin oxide (ITO). It was found that the electroluminescence (EL) intensity of the OLEDs were greatly improved by using PEDOT:PSS doped with MWNTs as hole-injection layer which might have resulted from the hole-injection ability improvement of the nanocomposites. Higher luminescence intensity and lower turn-on voltage were obtained by these devices and the luminance intensity obtained from the device with the hole-injection layer of PEDOT:PSS doped by 0.4 wt.% MWNTs was almost threefolds of that without doping.     

Investigating the performance of P3HT:PCBM organic solar cells involving gamma-irradiated PEDOT:PSS layer

In this work, we investigated for the first time the characteristics of (poly (3-hexylthiopene) and [6, 6]-phenyl C61-butyric acid methyl ester) (P3HT:PCBM) blends-based organic solar cell with 1.25?mg/mL boric-acid (H₃BO₃)-doped poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) layer which is irradiated under the 40 Gray (Gy) dose of gamma (γ) ray. Experimental results showed that the parameters of solar cell improved with exposure to low-dose gamma radiation. In particular, it has provided a significant improvement in short-circuit current density (J_sc) and power conversion efficiency (PCE). About 49% increase in PCE to 1.22% and 40% increase in J_sc to 6.28?mA/cm² was obtained between the bare device and the device containing irradiated PEDOT:PSS:H₃BO₃. Also, it was determined that the H₃BO₃-doped PEDOT:PSS is more stable to temperature. More importantly, solar cell containing gamma-irradiated PEDOT:PSS:H₃BO₃ showed best performance comparing to conventional PEDOT:PSS-based cell.     

Study of a ternary blend system for bulk heterojunction thin film solar cells

In this research, we report a bulk heterojunction(BHJ) solar cell consisting of a ternary blend system. Poly(3-hexylthiophene) P3 HT is used as a donor and [6,6]-phenyl C61-butyric acid methylester(PCBM) plays the role of acceptor whereas vanadyl 2,9,16,23-tetraphenoxy-29 H, 31H-phthalocyanine(VOPc Ph O) is selected as an ambipolar transport material. The materials are selected and assembled in such a fashion that the generated charge carriers could efficiently be transported rightwards within the blend. The organic BHJ solar cells consist of ITO/PEDOT:PSS/ternary BHJ blend/Al structure. The power conversion efficiencies of the ITO/ PEDOT:PSS/P3HT:PCBM/Al and ITO/PEDOT:PSS/P3HT:PCBM:VOPcPhO/Al solar cells are found to be 2.3% and 3.4%, respectively.     

阳极界面修饰对钙钛矿太阳能电池性能的影响

采用在聚(3,4-乙撑二氧噻吩)∶聚苯乙烯磺酸(Poly(3,4-ethylenedioxythiophene)∶Poly(styrenesulfonate),PEDOT∶PSS)阳极界面层上直接旋涂二甲基亚砜(Dimethyl Sulfoxide,DMSO)的方法,对PEDOT∶PSS薄膜进行修饰,以提高所制得的钙钛矿太阳能电池器件性能.在5000rpm转速条件下旋涂DMSO后,器件的能量转换效率达到11.43%,与PEDOT∶PSS阳极界面层未做任何修饰的器件相比,效率提高了29.15%.测试表征了修饰前后PEDOT∶PSS薄膜的透光性、表面形貌、电导率、器件的外量子效率曲线以及器件在光照和暗态下的J-V特性曲线,分析了器件性能提高的原因.结果表明:经过修饰的PEDOT∶PSS薄膜导电性显著增强,从而更加有利于器件阳极对空穴的抽取和收集;较未修饰时,器件的短路电流密度得到了大幅度提升,进而使得器件获得更高的能量转换效率.     

基于激子阻挡层的高效率绿光钙钛矿电致发光二极管

金属卤化物钙钛矿材料由于具有高的光致发光量子产率、高色纯度、带隙可调等杰出的光学性能,被作为发光材料广泛地用于制备钙钛矿电致发光二极管(perovskite light-emitting diodes,PeLEDs).虽然取得了较好的研究进展,但是其效率和稳定性还未达到商业化的要求,还需要进一步提高.为了提高PeLEDs的效率和稳定性,本文使用旋涂法,引入了一种具有宽带隙和较好空穴传输能力的有机小分子材料4,4′-cyclohexylidenebis[N,N-bis(p-tolyl)aniline](TAPC)作为激子阻挡层,获得了效率和寿命都得到提高的全无机PeLEDs.研究表明,PeLEDs效率和寿命得到提高的物理机制主要源于两方面:1)TAPC具有恰当的最高占有分子轨道能级,与PEDOT:PSS的最高占有分子轨道能级和CsPbBr3的价带边形成了阶梯式能级分布,有利于空穴注入和传输;同时TAPC具有较高的最低未占分子轨道能级,能够有效地阻止电子泄漏到阳极端,并能很好地将电子和激子限制在发光层内;2)TAPC层的引入可以避免钙钛矿发光层与强酸性的空穴注入材料Poly(3,4-ethylenedioxythiophene):poly(p-styrene sulfonate)(PEDOT:PSS)的直接接触,进而免除钙钛矿发光层由于与PEDOT:PSS的直接接触所导致的激子淬灭,从而提高了激子的发光辐射复合率.     

Pentacene as a hole transport material for high performance planar perovskite solar cells

A cost-effective and efficient organic semiconductor pentacene was developed as a hole transport layer (HTL) material to replace classical PEDOT:PSS for planar perovskite solar cells (PSCs). As expected, the pentacene based device exhibits power conversion efficiency (PCE) of 15.90% (J_sc of 19.44 mA/cm², V_oc of 1.07 V, and FF of 77%), comparable to the PEDOT:PSS based device (PCE of 15.65%, J_sc of 18.78 mA/cm², V_oc of 1.07 V, and FF of 77%) under the same experimental conditions. The excellent performance of vacuum deposited pentacene is mainly attributed to the high efficient charge extraction and transfer in device due to the high-quality perovskite film grown on the top of pentacene substrate and a favorable energy-level alignment together with a desired downward band bending formed at the perovskite/pentacene interface. Our research has confirmed that pentacene could be served as a promising HTL material to achieve effective and potentially economical planar type PSCs.     

Metal-electrode-free inverted organic photovoltaics using electrospray-deposited PEDOT:PSS and spin-coated HAT-CN exciton blocking layer

Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) films were fabricated using an electrospray deposition (ESD) method. The ESD PEDOT:PSS films exhibited higher PSS content on the surface than spin-coated PEDOT:PSS films, which results in a higher work function. Based on this result, metal-electrode-free inverted organic photovoltaics (OPVs) were fabricated. The ESD PEDOT:PSS was used as the top electrode on the poly(3-hexythiophene-2,5-diyl) (P3HT):[6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) light-absorbing layer. The power conversion efficiency (PCE) of OPVs was significantly increased with the 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile layer. The improved PCE would be attributed to the suppression of exciton quenching at the P3HT:PCBM and PEDOT:PSS interface.     

Poly(3,4-ethylene dioxythiophene): Poly(styrene sulfonate)的共振拉曼光谱研究

通过拉曼光谱方法分别对PEDOT:PSS掺杂和去掺杂状态进行了详细分析. 实验结果表明, 去掺杂的PEDOT:PSS由于其在激发波长附近的吸收增强而引起了共振效应, 拉曼信号得到大幅度增强, 可见, 以633 nm(He-Ne)激光为激发波长的拉曼光谱是研究PEDOT:PSS掺杂状态的有效方法. 此外, 显微拉曼光谱也是分析聚合物发光二极管器件内各层材料的有效手段.     

Modulating the Electrochromic Performances of Transmissive and Reflective Devices Using N,N-Dimethyl Formamide Modified Poly(3,4-Ethylenedioxythiophene)/Poly(Styrene Sulfonate) Blend as Active Layers

As one of the important factors which affect the properties and applications of conducting polymers, the electrical conductivity of a poly(3,4-ethylenedoxy-thiophene)/ poly(styrene sulfonate) (PEDOT: PSS) blend was adjusted by using various amount of an organic solvent (N,N-dimethyl formamide, DMF) as an additive. The conductivities of PEDOT: PSS thin films can be increased dramatically, from 1.0 S to 32.1 S cm^?1, with a 2/1 volume ratio of PEDOT: PSS/DMF loading after totally removing the organic solvent by annealing the film at 80° for 48 h in a vacuum oven. The optical contrasts of transmissive and reflective devices assembled using DMF-modified PEDOT: PSS as active layers exhibited a close relationship with the conductivity of PEDOT: PSS. Interestingly, high conductivity of PEDOT: PSS enhanced the contrast of a transmissive device, while high conductivity of PEDOT: PSS decreased the contrasts of a reflective device. The underlying reason is related to the different electrochromic mechanisms of these two types of device configurations.     

Enhanced thermoelectric performance of PEDOT:PSS films via ionic liquid post-treatment

Thermoelectric(TE)energy harvesting can effectively convert waste heat into electricity,which is a crucial technology to solve energy concerns.As a promising candidate for energy conversion,poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)has gained significant attention owing to its easy doping,high transparency,and solution processability.However,the TE performance of PEDOT:PSS still needs to be further enhanced.Herein,different approaches have been applied for tuning the TE properties:(i)direct dipping PEDOT:PSS thin films in ionic liquid;(ii)post-treatment of the films with concentrated sulfuric acid(H₂SO₄),and then dipping in ionic liquid.Besides,the same bis(trifluoromethanesulfonyl)amide(TFSI)anion and different cation salts,including 1-ethyl-3-methylimidazolium(EMIM+)and lithium(Li+),are selected to study the influence of varying cation types on the TE properties of PEDOT:PSS.The Seebeck coefficient and electrical conductivity of the PEDOT:PSS film treated with H2SO4EMIM:TFSI increase simultaneously,and the resulting maximum power factor is 46.7μW·m^-1·K^-2,which may be attributed to the ionic liquid facilitating the rearrangement of the molecular chain of PEDOT.The work provides a reference for the development of organic films with high TE properties.     

新型碳材料在钙钛矿太阳电池中的应用研究进展

新型碳材料如石墨烯及其氧化物、碳纳米管、富勒烯及石墨炔等因其优异的热学、力学、电学、光学性能成为了钙钛矿太阳电池研究的又一亮点. 本文总结了新型碳材料在钙钛矿太阳电池对电极、电子传输材料及空穴传输材料中的研究进展, 新型碳材料的引入有效地提高了钙钛矿电池的性能, 为下一步新型碳材料的应用开发以及钙钛矿电池器件的研究提供了新的思路.     

Hybrid solar cells with conducting polymers and vertically aligned silicon nanowire arrays: The effect of silicon conductivity

Organic/inorganic hybrid solar cells, based on vertically aligned n-type silicon nanowires (n-Si NWs) and p-type conducting polymers (PEDOT:PSS), were investigated as a function of Si conductivity. The n-Si NWs were easily prepared from the n-Si wafer by employing a silver nanodot-mediated micro-electrochemical redox reaction. This investigation shows that the photocurrent-to-voltage characteristics of the n-Si NW/PEDOT:PSS cells clearly exhibit a stable rectifying diode behavior. The increase in current density and fill factor using high conductive silicon is attributed to an improved charge transport towards the electrodes achieved by lowering the device's series resistance. Our results also show that the surface area of the nanowire that can form heterojunction domains significantly influences the device performance.