Investigations of materials and device structures for organic semiconductor solar cells

Whitlock, Jonathan B.; Panayotatos, P.; Sharma, Ganesh D.; Cox, Mary D.; Sauers, Ronald R.; Bird, George R.

doi:10.1117/12.143713

Cited by 91 publications

(19 citation statements)

References 38 publications

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“…[1][2][3][4][5][6][7]. Many of these applications are based on the electrical properties of these materials, and detailed understanding of the same requires an accurate knowledge of molecular as well as crystal structures.…”

Section: Introductionmentioning

confidence: 99%

Studies on polymorphic modifications of copper phthalocyanine

Achar

Sannegowda

2004

Journal of Solid State Chemistry

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Section: Introductionmentioning

confidence: 99%

Studies on polymorphic modifications of copper phthalocyanine

Achar

Sannegowda

2004

Journal of Solid State Chemistry

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“…Jonathan and his coworkers were having difficulties with fabricating devices with acute leakages. 8 They mainly attributed the leaky diodes to the material impurities, which may have caused the formation of local short paths for reverse currents. Wohrle and his colleagues investigated photovoltaic properties as a function of material purities.…”

mentioning

confidence: 99%

Efficient Organic Photovoltaic Device Using a Sublimated Subphthalocyanine as an Electron Donor

Liu

Lee

et al. 2012

ECS Solid State Letters

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In this letter, an efficient subphthalocyanine (SubPc)/C 60 heterojunction organic photovoltaic device was demonstrated. The power conversion efficiency was improved from 2.7% to 4.3% by the sublimation of SubPc. The atomic force microscopic images showed that the crystallinity was improved with the sublimation of the SubPc, leading to the significantly enhanced hole mobility of SubPc in orders of magnitude as estimated by the space-charge limited current. The external quantum efficiency spectra further confirmed the improved charge collection efficiency as a result of the increase in the hole mobility of SubPc due to the unchanged spectral shape over the entire spectrum.Recently, considerable progress in organic photovoltaic (OPV) industries has made realistic commercialization possible. 1 The first outstanding breakthrough of OPV devices was demonstrated by Tang with the concept of a donor/acceptor interface, which achieved a power conversion efficiency (PCE) of about 1%. 2 No significant improvement was made until Forrest and his coworkers introduced a new device structure and acceptor material. 3,4 They suggested that for the exciton blocking layer (EBL), the charge collection efficiency can be improved, with the long exciton diffusion length being important to device optimization. After this finding, the choice of materials became an efficient route to the enhancement in device performance. The materials with long diffusion length, such as fullerene (C 60 ) and pentacene, can lead to high external quantum efficiency (EQE) due to the efficient diffusion of excitons and charge collection. 4,5 In addition, to improve the electrical property of OPV devices, light harvest can also be enhanced by combining the material's absorption with compensated spectral coverage. 6,7 These results successfully showed a near superimposition of the individual photocurrents for each single-donor device.Another proposed approach for material modification is the purity of the materials. Jonathan and his coworkers were having difficulties with fabricating devices with acute leakages. 8 They mainly attributed the leaky diodes to the material impurities, which may have caused the formation of local short paths for reverse currents. Wohrle and his colleagues investigated photovoltaic properties as a function of material purities. 9 They revealed that the non-sublimated materials resulted in a rough surface on the thin film. Therefore, pinholes emerged and formed the short circuits that deteriorated the device performance. The Forrest group showed that the PCE of copper phthalocyanine (CuPc)-based OPV devices can be enhanced over five times when the donor material was efficiently purified. 10 They used space-charge limited currents to calculate the hole mobility of CuPc thin films under different purifications. As a result, the less purified thin film exhibited low carrier mobility, leading to a small fill factor (FF).Subphthalocyanine (SubPc) is a promising candidate for a donor material due to its extremely low-lying highest occupied ...

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“…An extensive review of these materials has been reported by Leznoff and Lever [I]. These materials have also shown promise for photoconductive and photovoltaic response of which the current state of research has also been extensively reviewed by Whitlock el al [2], Law [3] and Martin el al [4], It has been widely reported that oxygen acts as a dopant in phthalocyanines and is also responsible for the formation of a space charge region near rectifying electrodes. As a consequence, many workers have used exposure to air for days before depositing the top metal contact in sandwich structures in order to oxygen dope the devices; after this time the oxygen doping is thought to be complete.…”

Section: Introductionmentioning

confidence: 99%

NO2 detection at room temperature with copper phthalocyanine thin film devices

Newton

Starke

Willis

et al. 2000

Sensors and Actuators B: Chemical

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In this work we report the effect of post deposition film treatment on the N0 2 sensing properties of CuPc thin films for room temperature operation. The gas sensitive response of the electrical conductivity to doping with N0 2 , doping with oxygen (in air) and cooling to 77K in liquid nitrogen are reported. The pretreatment with N0 2 is shown to improve the gas sensing properties by providing both an increase in the magnitude of the conductivity change for a given N0 2 concentration and a significant improvement in the recovery time. Data is analysed using an Elovich model, which suggests that the cooled devices have the best fit to this model; the data for the N0 2 doped devices suggest a Langmuir behaviour. For all devices, a simple time derivative of the change in current provides a measure of concentration for real time gas sensing applications.

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Investigations of materials and device structures for organic semiconductor solar cells

Cited by 91 publications

References 38 publications

Studies on polymorphic modifications of copper phthalocyanine

Studies on polymorphic modifications of copper phthalocyanine

Efficient Organic Photovoltaic Device Using a Sublimated Subphthalocyanine as an Electron Donor

NO2 detection at room temperature with copper phthalocyanine thin film devices

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