共查询到20条相似文献，搜索用时 15 毫秒
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Sarah R. Cowan Wei Lin Leong Natalie Banerji Gilles Dennler Alan J. Heeger 《Advanced functional materials》2011,21(16):3083-3092
Small amounts of impurity, even one part in one thousand, in polymer bulk heterojunction solar cells can alter the electronic properties of the device, including reducing the open circuit voltage, the short circuit current and the fill factor. Steady state studies show a dramatic increase in the trap‐assisted recombination rate when [6,6]‐phenyl C84 butyric acid methyl ester (PC84BM) is introduced as a trap site in polymer bulk heterojunction solar cells made of a blend of the copolymer poly[N‐9″‐hepta‐decanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole) (PCDTBT) and the fullerene derivative [6,6]‐phenyl C61 butyric acid methyl ester (PC60BM). The trap density dependent recombination studied here can be described as a combination of bimolecular and Shockley–Read–Hall recombination; the latter is dramatically enhanced by the addition of the PC84BM traps. This study reveals the importance of impurities in limiting the efficiency of organic solar cell devices and gives insight into the mechanism of the trap‐induced recombination loss. 相似文献
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Rebecca Saive Michael Scherer Christian Mueller Dominik Daume Janusz Schinke Michael Kroeger Wolfgang Kowalsky 《Advanced functional materials》2013,23(47):5854-5860
The charge transport in organic solar cells is investigated by surface potential measurements via scanning Kelvin probe microscopy. Access to the solar cell's cross‐section is gained by milling holes with a focused ion beam which enables the direct scan along the charge transport path. In a study of poly(3‐hexylthiophene):1‐(3‐methoxycarbonyl)propyl‐1‐phenyl[6,6]C61 (P3HT:PCBM) bulk heterojunction solar cells, the open circuit voltage is built up at the top contact. A comparison of the potential distribution within normal and inverted solar cells under operation exhibits strongly different behaviors, which can be assigned to a difference in interface properties. 相似文献
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We present a new recipe for a solution-processed titanium oxide (TiOx) based electron transport layer at room temperature. Due to its high chemical compatibility with all types of organic blends (semi-crystalline or amorphous) and it is good adhesion to both surfaces of glass/ITO substrate and the active layer (blend), the buffer layer is suitable for use in organic solar cell devices with conventional, inverted or multi-junction structures. The main goal of this recipe is producing with easiness an repeatable and stable precursor that will leads to titanium oxide buffer layer each time with the same quality. Since the processing of the titanium oxide layer itself does not require any initial or additional treatment before and after the coating, and can even be carried in air as well as under protective atmosphere, our room temperature solution-processed electron transport layer is highly versatile and very promising for cost effective mass production of organic solar cells. 相似文献
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Francesco Toschi Daniele Catone Patrick O'Keeffe Alessandra Paladini Stefano Turchini Janardan Dagar Thomas M. Brown 《Advanced functional materials》2018,28(26)
The insertion of a DNA nanolayer into polymer based solar cells, between the electron transport layer (ETL) and the active material, is proposed to improve the charge separation efficiency. Complete bulk heterojunction donor–acceptor solar cells of the layered type glass/electrode (indium tin oxide)/ETL/P3HT:PC70BM/hole transport layer/electrode (Ag) are investigated using femtosecond transient absorption spectroscopy both in the NIR and the UV–vis regions of the spectrum. The transient spectral changes indicate that when the DNA is deposited on the ZnO nanoparticles (ZnO‐NPs) it can imprint a different long range order on the poly(3‐hexylthiophene) (P3HT) polymer with respect to the non‐ZnO‐NPs/DNA containing cells. This leads to a larger delocalization of the initially formed exciton and its faster quenching which is attributed to more efficient exciton dissociation. Finally, the temporal response of the NIR absorption shows that the DNA promotes more efficient production of charge transfer states and free polarons in the P3HT cation indicating that the increased exciton dissociation correlates with increased charge separation. 相似文献
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Photo-generated charge behaviors in the bulk heterojunctions (BHJs) of all-polymer solar cells (PSCs) are studied by Kelvin probe force microscopy (KPFM). Root-mean-square deviations (RMSDs, Rq) of the contact potential difference (CPD) images are applied to quantitatively characterize the phase segregations of the BHJs. When the BHJs are illuminated, CPD values and Rq of CPD images are changed, which attributes to the photo-generated charge transfer and accumulation. Inner structures of the BHJ are thus extrapolated by studying the charge behaviors, demonstrating KPFM an effective technique to study the relationship between inner structures and photovoltaic activities in all-PSCs. 相似文献
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Di Xue Weijie Gong Chi Yan Yingying Zhang Jie Lu Yao Yin Jidong Zhang Zi Wang Lizhen Huang Lifeng Chi 《Advanced functional materials》2024,34(38):2402884
Negative photoconductive phototransistors, referring to transistors that exhibit a decrease in photocurrent under illumination, have the potential to revolutionize optoelectronic applications involving light, such as optoelectronic logic circuits and visual neural simulation. Currently, achieving negative photoconductivity (NPC) requires complex material design or interface structure construction. However, achieving precise control over NPC behaviors poses a significant challenge. Herein, a simple yet effective strategy is demonstrated for realizing controllable NPC responses in organic phototransistors through ambipolar transport modulation. Due to the controversy between the preferred exciton dissociation/charge separation direction and the gate electric field driven charge drift direction, the main semiconductor channel (n- or p-channel) exhibits NPC behavior under illumination. The validity of this mechanism has been confirmed through intensive studies by varying the component and combination of the p-n heterostructure. Moreover, devices utilizing ambipolar transport exhibit a wavelength-selectivity NPC response due to the absorption characteristics of the combined semiconductor materials. Most encouragingly, by incorporating both negative and positve photoconductivity along with wavelength-selective responses, high-contrast image sensing, information encryption and decryption, as well as optoelectronic logic circuit design is successfully achieved. This work promotes the design and development of bidirectional optoelectronic devices and offers a new route for developing attractive multifunctional optoelectronic devices. 相似文献
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Two n-type conjugated D-A copolymers with perylene diimide (PDI) as acceptor unit and benzodithiophene (BDT) as donor unit, P(PDI-BDT-Ph) and P(PDI-BDT-Th), were synthesized and applied as electron acceptor in all-polymer solar cells (all-PSCs). P(PDI-BDT-Ph) and P(PDI-BDT-Th) films exhibit similar absorption spectra in the visible region with optical bandgap (Eg) of 1.65 eV and 1.55 eV respectively, and the identical LUMO level of −3.89 eV. The all-PSCs based on P(PDI-BDT-Ph) as acceptor and PTB7-Th as donor demonstrated a power conversion efficiency (PCE) of 4.31% with a short-circuit current density (Jsc) of 11.94 mA cm−2, an open-circuit voltage (Voc) of 0.81 V, and a fill factor (FF) of 44.49%. By contrast, the corresponding all-PSCs with P(PDI-BDT-Th) as acceptor showed a relative lower PCE of 3.58% with a Jsc of 11.36 mA cm−2, Voc of 0.79 V, and FF of 40.00%. 相似文献
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利用简单的低温工艺制备了纳米晶纤锌矿结构的ZnO,用高分辨透射电镜(HRTEM)、X射线衍射(XRD) 和光致发光(PL)技术进行了表征.利用纳米晶ZnO和共轭聚合物2.甲氧基.5.(3,7.二甲基辛氧基)对苯撑乙烯 (MDMO-PPV)制备了结构为ITO/PEDOT：PSS/ZnO：MDMO-PPV/A1的有机/无机复合体异质结太阳电池,作为 对比,同时制备了ITo/PEDOT：PsS/MDMo-PPV/Al结构的纯有机聚合物电池.实验结果表明,添加纳米晶ZnO 使其能量转换效率提高了约550倍.PL谱测试结果表明这是由于有高电子亲合能的ZnO提高了电子空穴对分离 的能力.另外,光伏性能的提高可能也与ZnO引起的电子传输能力的提高有关.此外,本文分析了ZnO：MDMOPPV体异质结电池性能低于传统电池的原因,并提出了进一步提高其性能的方法. 相似文献
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Two donor-acceptor polymers P8 and P9 based on 5,6-difluoro-benzo[1,2,5]thiadiazole unit have been prepared and applied as the donor materials in polymer solar cells. Due to the slight difference between electronic structures of thiophene and selenophene, P8 and P9 show similar absorption spectra and similar frontier energy levels. However, the pristine P8:PC71BM and P9:PC71BM blend films display distinct morphologies as revealed by AFM measurement. After the addition of DIO, both blend films feature a nanoscale interconnected-network structure, which leads to the enhancement in solar cells performance with PCE up to 6.73% and 6.84% for P8 and P9, respectively. Alternating current impedance spectrometry measurements revealed that high surface roughness could improve the PCE of P8-based PSCs, while in P9-based PSCs DIO can enhance hole and electron mobilities of the active layer. 相似文献
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研究和制作了一种新型Au/n-ZnO/p-Si结构的肖特基发射极、异质结集电极紫外增强双极型光电三极管.分析了器件原理,测试了I-V特性、C-V特性以及器件的光谱响应,从200到400nm的紫外光响应灵敏度得到明显增强而对大于400nm的可见光的响应特性得到保留.实验显示Au/n-ZnO/p-Si结构的紫外增强型的光电三极管对紫外光的响应明显增强,对371nm波长的紫外光的灵敏度是普通n-ZnO/p-Si异质结紫外光电二极管道的5～10倍. 相似文献
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Zhao Li Sai‐Wing Tsang Xiaomei Du Ludmila Scoles Gilles Robertson Yanguang Zhang Floyd Toll Ye Tao Jianping Lu Jianfu Ding 《Advanced functional materials》2011,21(17):3331-3336
A series of alternating copolymers of cyclopenta[2,1‐b;3,4‐b′]dithiophene (CPDT) and thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) have been prepared and characterized for polymer solar cell (PSC) applications. Different alkyl side chains, including butyl (Bu), hexyl (He), octyl (Oc), and 2‐ethylhexyl (EH), are introduced to the TPD unit in order to adjust the packing of the polymer chain in the solid state, while the hexyl side chain on the CPDT unit remains unchanged to simplify discussion. The polymers in this series have a simple main chain structure and can be synthesized easily, have a narrow band gap and a broad light absorption. The different alkyl chains on the TPD unit not only significantly influence the solubility and chain packing, but also fine tune the energy levels of the polymers. The polymers with Oc or EH group have lower HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels, resulting higher open circuit voltages (Voc) of the PSC devices. Power conversion efficiencies (PCEs) up to 5.5% and 6.4% are obtained from the devices of the Oc substituted polymer (PCPDTTPD‐Oc) with PC61BM and PC71BM, respectively. This side chain effect on the PSC performance is related to the formation of a fine bulk heterojunction structure of polymer and PCBM domains, as observed with atomic force microscopy. 相似文献
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Organic Photovoltaics: Photovoltaic Function and Exciton/Charge Transfer Dynamics in a Highly Efficient Semiconducting Copolymer (Adv. Funct. Mater. 1/2014) 
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下载免费PDF全文 Jodi M. Szarko Brian S. Rolczynski Sylvia J. Lou Tao Xu Joseph Strzalka Tobin J. Marks Luping Yu Lin X. Chen 《Advanced functional materials》2014,24(1):2-2
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Jodi M. Szarko Brian S. Rolczynski Sylvia J. Lou Tao Xu Joseph Strzalka Tobin J. Marks Luping Yu Lin X. Chen 《Advanced functional materials》2014,24(1):10-26
Exciton dissociation is a key step for the light energy conversion to electricity in organic photovoltaic (OPV) devices. Here, excitonic dissociation pathways in the high‐performance, low bandgap “in‐chain donor–acceptor” polymer PTB7 by transient optical absorption (TA) spectroscopy in solutions, neat films, and bulk heterojunction (BHJ) PTB7:PC71BM (phenyl‐C71‐butyric acid methyl ester) films are investigated. The dynamics and energetics of the exciton and intra‐/intermolecular charge separated states are characterized. A distinct, dynamic, spectral red‐shift of the polymer cation is observed in the BHJ films in TA spectra following electron transfer from the polymer to PC71BM, which can be attributed to the time evolution of the hole–electron spatial separation after exciton splitting. Effects of film morphology are also investigated and compared to those of conjugated homopolymers. The enhanced charge separation along the PTB7 alternating donor–acceptor backbone is understood by intramolecular charge separation through polarized, delocalized excitons that lower the exciton binding energy. Consequently, ultrafast charge separation and transport along these polymer backbones reduce carrier recombination in these largely amorphous films. This charge separation mechanism explains why higher degrees of PCBM intercalation within BHJ matrices enhances exciton splitting and charge transport, and thus increase OPV performance. This study proposes new guidelines for OPV materials development. 相似文献
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A series of D-A type conjugated polymers based on (E)-1,2-bis(3-dodecyllthiophen-2-yl)ethene (TV) as electron donor unit and with different repeating subunits, PTVBO8, PTVBT8, PTVTBO12, and PTVTBT12 were synthesized for use in organic field effect transistors and bulk heterojunction organic photovoltaics. Upon incorporation of alkoxy substituents in acceptor units, benzooxadiazole (BO) and benzothiadiazole (BT), polymer solubility improved and higher molecular weight polymers were obtained. In addition, all copolymers showed favorable thermal stability (Td > 300 °C), and low band gap properties (1.49–1.67 eV). The thiophene-flanked TV-TBX copolymers, PTVTBO12 and PTVTBT12, exhibited higher molecular weight and superior device performance in both OFETs and OPVs compared with the TV-BX copolymers. The electronic energy levels of copolymers were strongly influenced by the nature of acceptor units, while optical band gaps and shape of molecular orientation of polymer chains were affected by the presence or absence of thiophene spacer. Charge carrier mobilities in TV-TBX copolymers were 1 order of magnitude greater than in TV-BX copolymers. OFETs based on a PTVTBT12 with TG/BC configuration displayed the highest hole mobility of 0.48 cm2 V−1 s−1. The photovoltaic device containing a PTVTBO12:PC71BM (1:2 w/w) blend system exhibited best performance with a Voc of 0.56 V, a short-circuit current density (Jsc) of 13.1 mA cm−2, a fill factor (FF) of 69%, and a power conversion efficiency (PCE) of 5.0%. 相似文献
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研究和制作了一种新型Au/n-ZnO/p-Si结构的肖特基发射极、异质结集电极紫外增强双极型光电三极管.分析了器件原理,测试了I-V特性、C-V特性以及器件的光谱响应,从200到400nm的紫外光响应灵敏度得到明显增强而对大于400nm的可见光的响应特性得到保留.实验显示Au/n-ZnO/p-Si结构的紫外增强型的光电三极管对紫外光的响应明显增强,对371nm波长的紫外光的灵敏度是普通n-ZnO/p-Si异质结紫外光电二极管道的5～10倍. 相似文献
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I. Riedel E. von&#x;Hauff J. Parisi N. Martín F. Giacalone V. Dyakonov 《Advanced functional materials》2005,15(12):1979-1987
A novel fullerene derivative, 1,1‐bis(4,4′‐dodecyloxyphenyl)‐(5,6) C61, diphenylmethanofullerene (DPM‐12), has been investigated as a possible electron acceptor in photovoltaic devices, in combination with two different conjugated polymers poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐para‐phenylene vinylene] (OC1C10‐PPV) and poly[3‐hexyl thiophene‐2,5‐diyl] (P3HT). High open‐circuit voltages, VOC = 0.92 and 0.65 V, have been measured for OC1C10‐PPV:DPM‐12‐ and P3HT:DPM‐12‐based devices, respectively. In both cases, VOC is 100 mV above the values measured on devices using another routinely used fullerene acceptor, [6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM). This is somewhat unexpected when taking into account the identical redox potentials of both acceptor materials at room temperature. The temperature‐dependent VOC reveals, however, the same effective bandgap (HOMOPolymer–LUMOFullerene; HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) of 1.15 and 0.9 eV for OC1C10‐PPV and P3HT, respectively, independent of the acceptor used. The higher VOC at room temperature is explained by different ideality factors in the dark‐diode characteristics. Under white‐light illumination (80 mW cm–2), photocurrent densities of 1.3 and 4.7 mA cm–2 have been obtained in the OC1C10‐PPV:DPM‐12‐ and P3HT:DPM‐12‐based devices, respectively. Temperature‐dependent current density versus voltage characteristics reveal a thermally activated (shallow trap recombination limited) photocurrent in the case of OC1C10‐PPV:DPM‐12, and a nearly temperature‐independent current density in P3HT:DPM‐12. The latter clearly indicates that charge carriers traverse the active layer without significant recombination, which is due to the higher hole‐mobility–lifetime product in P3HT. At the same time, the field‐effect electron mobility in pure DPM‐12 has been found to be μe = 2 × 10–4 cm2 V–1 s–1, that is, forty‐times lower than the one measured in PCBM (μe = 8 × 10–3 cm2 V–1 s–1). 相似文献