Fill factor in organic solar cells

Gupta, Dhritiman; Mukhopadhyay, Sabyasachi; Narayan, K. S.

doi:10.1016/j.solmat.2008.06.001

Cited by 219 publications

(125 citation statements)

References 40 publications

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“…4 in Ref. 44) show that there is a reduction in current density and increase in voltage across the active layer along the dimension x in Fig. 8.…”

Section: On the Underlying Mechanism Of The Size Effect In Opv Cellsmentioning

confidence: 82%

“…44 From the shape of the J ph curve it is possible to characterize the carrier photogeneration and transport in different regimes. Indeed, the behavior of the illuminated J-V response depends on the drift length (L D ¼ msE, where m is the mobility, s is the lifetime of the charge carriers, and E is the field across the device) of the electrons (e) and holes (h) and the ratio (b) of their drift lengths (b ¼ m e s e /m h s h ).…”

Section: Light Intensity Dependence Ff: Evolution Of the Shape J Pmentioning

confidence: 99%

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Origin of size effect on efficiency of organic photovoltaics

Manor

Katz

Tromholt

et al. 2011

Journal of Applied Physics

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It is widely accepted that efficiency of organic solar cells could be limited by their size. However, the published data on this effect are very limited and none of them includes analysis of light intensity dependence of the key cell parameters. We report such analysis for bulk heterojunction solar cells of various sizes and suggest that the origin of both the size and the light intensity effects should include underlying physical mechanisms other than conventional series resistance dissipation. In particular, we conclude that the distributed nature of the ITO resistance and its influence on the voltage dependence of photocurrent and dark current is the key to understanding size limitation of the organic photovoltaics (OPV) efficiency. Practical methods to overcome this limitation as well as the possibility of producing concentrator OPV cells operating under sunlight concentrations higher than 10 suns are discussed.

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“…4 in Ref. 44) show that there is a reduction in current density and increase in voltage across the active layer along the dimension x in Fig. 8.…”

Section: On the Underlying Mechanism Of The Size Effect In Opv Cellsmentioning

confidence: 82%

Section: Light Intensity Dependence Ff: Evolution Of the Shape J Pmentioning

confidence: 99%

Origin of size effect on efficiency of organic photovoltaics

Manor

Katz

Tromholt

et al. 2011

Journal of Applied Physics

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“…We exclude variation in anode and probe resistance, which remain constant and consider rather the contact resistances at the ITO/ZnO and ZnO/Active layer interfaces. In the former Ohmic contact was confirmed by Considering R sh which originates from the leakage currents induced by pinholes and defects in the device [40] we have measured J-V characteristics in the dark, Figure 6. There is a systematic increase in the leakage current as processing temperature is increased and it is noteworthy that the 25 °C ETL based device shows a non-zero bias at short-circuit due to carrier accumulation at the interface associated with the high resistivity of the film.…”

Section: Opv Device Performance With Etl Processing Temperature Variamentioning

confidence: 84%

“…In addition to compositional changes in the ETL that may improve the charge transport we consider changes occurring in the ITO where the measured R S increases from 11.3 Ω/⧠ in our as-received substrates to 51.7 Ω/⧠ following the same thermal treatment as applied to the 450 °C-ZnO, Supplementary Figure 4. This will contribute to the overall increase in R S which is a combination of the bulk resistance of the active layer, interlayers and electrodes, in addition to the contact resistance of every interface and the probe resistance [40] . We exclude variation in anode and probe resistance, which remain constant and consider rather the contact resistances at the ITO/ZnO and ZnO/Active layer interfaces.…”

Section: Opv Device Performance With Etl Processing Temperature Variamentioning

confidence: 99%

Low‐Temperature Solution‐Processed Electron Transport Layers for Inverted Polymer Solar Cells

Zhang

Faria

Morbidoni

et al. 2016

Adv Elect Materials

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Processing temperature is highlighted as a convenient means of controlling the optical and charge transport properties of solution processed electron transport layers (ETLs) in inverted polymer solar cells. Using the well-studied active layer -poly(3-hexylthiophene-2,5-diyl) (P3HT):indene-C 60 bisadduct (ICBA) -we show the influence of ETL processing temperatures from 25 °C -450 °C, reporting the role of crystallinity, structure, charge transport and Fermi level (E F ) on numerous device performance characteristics. We determine that an exceptionally low temperature processed ETL (110 °C) increases that device power conversion efficiency (PCE) by a factor greater than 50% compared with a high temperature (450 °C) processed ETL. Modulations in device series and shunt resistance, induced by changes in the ETL transport properties are observed in parallel to significant changes in device open circuit voltage attributed to changes on the E F of the ETLs. Our work highlights the importance of interlayer control in multilayer photovoltaic devices and presents a convenient material compatible with future flexible and roll-to-roll processes.

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“…In addition, both the hole and electron mobilities usually change simultaneously, which obscures the fundamental relationship between the mobility and FF. Another aspect to consider is that there are plenty of device-related parameters, such as the active layer thickness as well as shunt-and series-resistances 4 that influence the FF of a solar cell. Thus, the data in the literature can vary very strongly for a given material system.…”

Section: Introduction a Backgroundmentioning

confidence: 99%

Mobility and fill factor correlation in geminate recombination limited solar cells

Andersson¹,

Müller²,

Badada³

et al. 2011

Journal of Applied Physics

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Empirical data for the fill factor as a function of charge carrier mobility for two different polymer:fullerene systems is presented and analyzed. The results indicate that charge extraction depth limitations and space charge effects are inconsistent with the observed behavior, and the decrease in the fill factor is, instead, attributed to the field-dependent charge separation and geminate recombination. A solar cell photocurrent limited by the Onsager-Braun charge transfer exciton dissociation is shown to be able to accommodate the experimental observations. Charge dissociation limited solar cells always benefit from increased mobilities, and the negative contribution from the reduced charge separation is shown to be much more important for the fill factor in these material systems than any adverse effects from charge carrier extraction depth limitations or space charge effects due to unbalanced mobilities. The logarithmic dependence of the fill factor on the mobility for such a process is also shown to imply that simply increasing the mobilities is an impractical way to reach very high fill factors under these conditions since unrealistically high mobilities are required. A more controlled morphology is, instead, argued to be necessary for high performance.

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Fill factor in organic solar cells

Cited by 219 publications

References 40 publications

Origin of size effect on efficiency of organic photovoltaics

Origin of size effect on efficiency of organic photovoltaics

Low‐Temperature Solution‐Processed Electron Transport Layers for Inverted Polymer Solar Cells

Mobility and fill factor correlation in geminate recombination limited solar cells

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