Influence of nanoscale morphology in small molecule organic solar cells

Vogel, M.; Strotmann, J.; Johnev, B.; Lux‐Steiner, M.; Fostiropoulos, K.

doi:10.1016/j.tsf.2005.12.030

Cited by 30 publications

(21 citation statements)

References 12 publications

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“…2, with increasing T sub from 30 up to 90 1C, to enhance the surface diffusion energy of the adhered organic molecules, the average surface roughness observed in C 60 interface then decreases from 8.870.4 down to 2.770.3 nm. The strong T sub -dependence of surface morphology in molecular solids is in good agreement with those results obtained in CuPc:C 60 (1:1) blend films with T sub varied from 30 to 145 1C [18]. For T sub X150 1C, formation of line fiber was observed in the surface of CuPc films [17].…”

Section: Resultssupporting

confidence: 87%

“…The experimental values of short-circuit current density J sc , open-circuit voltage V oc , and fill factor FF determined for these OPV cells fabricated at T sub ¼ 30 and 90 1C are listed in Table 1. Because of low incident optical intensity and large series resistance, the values of J sc observed in this work are much smaller as compared to the results obtained by using a simulated AM1.5G illumination of 75-100 mW/ cm 2 [8,9,18]. However, with respect to T sub -dependence, one can see that OPV cells fabricated at T sub =90 1C can deliver more power output (about a factor of 5) than those fabricated at T sub =30 1C.…”

Section: Article In Presscontrasting

confidence: 64%

“…The overall performance of OPV cells is sensitively dependent on light absorption, exciton diffusion and dissociation behaviors, and free-charges transport and collection ability. Therefore, the choice of materials [3][4][5][6][7][8][9][10][11], the design of cell structures [10][11][12][13][14][15][16] and the deposition conditions [17,18] all play important roles in determining the power conversion efficiency (PCE) of OPV cells.…”

Section: Introductionmentioning

confidence: 99%

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Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

Chiu

Juey

et al. 2008

Journal of Crystal Growth

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Section: Resultssupporting

confidence: 87%

Section: Article In Presscontrasting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

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Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

Chiu

Juey

et al. 2008

Journal of Crystal Growth

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“…In blend photovoltaic cells with no or very little phase separation between donor ͑here, Pc͒ and acceptor ͑C 60 ͒ as in the present case 15 excitons are always generated close to the Pc-C 60 interface and therefore dissociate very quickly. 16 Accordingly the exciton density in the blend film is too low to account for significant nonradiative recombination.…”

Section: -mentioning

confidence: 56%

On the function of a bathocuproine buffer layer in organic photovoltaic cells

Vogel¹,

Doka²,

Breyer³

et al. 2006

Applied Physics Letters

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182

120

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The role of bathocuproine ͑BCP͒ buffer layer inserted between active layer and Al contact in photovoltaic cells based on phthalocyanine ͑Pc͒ and C 60 was investigated. Photoluminescence ͑PL͒ experiments show exciton quenching at the C 60 -Al interface to be strongly reduced by inserting BCP. Current-voltage characteristics of photovoltaic cells with planar geometry front electrode/ Pc/ C 60 / BCP/ Al show that BCP dramatically improves electron transport out of the C 60 film into the Al electrode. The tenfold increase in power conversion efficiency ͑͒ with BCP can mostly be attributed to the latter effect. BCP does not improve in photovoltaic cells with blend film geometry front electrode/Pc: C 60 / Al.

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“…When deposited by co-evaporation the cells based on ZnPc:C 60 are quite disappointing, even if a mild annealing treatment improves significantly the cells performances 80,81 . Attempts to achieve bulk-heterojunction using small molecules yields devices with power efficiencies smaller than those achieve in multiplayer structures.…”

Section: From the Bilayer To The Multiple Heterojunctions Devicesmentioning

confidence: 99%

Organic Photovoltaic Cells: History, Principle and Techniques

Bérnède

2008

J. Chil. Chem. Soc.

147

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In this review we present an overview of the different organic solar cells families. After recalling shortly the specificities of organic materials, the band structure, the electronic properties and the charge separation process in organic materials are shortly described. Then the new organic solar cell concepts are presented. Plastic organic solar cells consist either of two organic layers or a homogeneous mixture of two organic materials. One of them -either an organic dye or a semiconducting polymer -donates the electrons. The other component serves as the electron acceptor. Principles of these multi-layers and bulk heterojunctions are presented and discussed. Then some typical examples are presented, showing the fast evolution of the cells performances. Finally, a specific attention is devoted to the interfaces electrodes/organics. Indeed recent results show that, at least in the case of multi-layers cells, the introduction of thin buffer layers at the interfaces cathode/organic acceptor and/or anode/organic donor, can strongly improve the efficiency of the organic solar cells. About the interface organic acceptor/cathode, we report the influence of an exciton-blocking layer and/or an Al 2 O 3 thin layer on the efficiency of CuPc/C 60 based photovoltaic cells. The presence, or not, of a thin Al 2 O 3 layer depends on the encapsulating process of the devices. In the case of glass/ITO/CuPc/C 60 /Al cells, the presence of an Al 2 O 3 thin layer at the interface "organic acceptor/aluminium" increases strongly the open circuit voltage of the cells but decreases slightly their short circuit current and fill factor. In the case of glass/ITO/CuPc/C 60 /Alq 3 /Al cells, the open circuit voltage is systematically higher than without Alq 3 . However, in that case, the presence of Al 2 O 3 does not improve significantly the cell performances. All these results are discussed in terms of series and shunt resistance values related to possible oxygen contamination and organic covalent action with the Al films. The effectiveness of these different phenomena depends on the presence, or not, of Alq 3 and/or Al 2 O 3 layers.About the interface anode/organic donor, it is shown that an ultra thin metallic film improves significantly the short circuit current and the cell performances. The anode in plastic solar cells, which is a transparent conductive oxide (TCO), is usually an indium tin oxide film (ITO). Indeed, when a ZnO anode is used, cells performances are far from those achieved with ITO. However, strong improvement of the cells efficiency is encountered when an ultra thin buffer layer is introduced between the ZnO and the organic film. The presence of this ultra thin buffer layer at the surface of the TCO allows decreasing the performance difference between the cells using ITO and those using ZnO. More generally such ultra thin buffer layer improves the solar cells performances.

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Influence of nanoscale morphology in small molecule organic solar cells

Cited by 30 publications

References 12 publications

Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

Effects of source and substrate temperatures on the properties of ITO/CuPc/C60 heterostructure prepared by physical vapor deposition

On the function of a bathocuproine buffer layer in organic photovoltaic cells

Organic Photovoltaic Cells: History, Principle and Techniques

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