Investigation of defects by admittance spectroscopy measurements in poly (3-hexylthiophene):(6,6)-phenyl C61-butyric acid methyl ester organic solar cells degraded under air exposure

Khelifi, Samira; Decock, Koen; Lauwaert, Johan; Vrielinck, Henk; Spoltore, Donato; Piersimoni, Fortunato; Manca, Jean; Belghachi, Abderrahmane; Burgelman, Marc

doi:10.1063/1.3658023

Cited by 123 publications

(130 citation statements)

References 34 publications

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“…4a caused by reaction of P3HT: PCBM with O 2 the degradation of mobility and resulting in a reduction of the dissociationprobability this behavior explain by many of the photo-generated bound electron-hole pairs will not dissociate into free carriers and increase the rate of non-radiative recombinationFig. 4bas result the degradation of the efficiency The same behavior has been reported in[6].…”

supporting

confidence: 65%

“…Record conversion efficiency 3.5 to 5% has been obtained for blend based on interpenetrating networks of conjugated polymers with fullerenes such as P3HT: PCBM [5]. In other hand the degradation is a complicated problem related in those devices when exposed to air, the increase p-doping due to reaction with oxygen leads to degradation of performance, the factor major explain this behavior is trap formation [6][7]. Also the organic solar cells are sensitive to temperature, the increase in temperature reduces the band gap and affects most of semiconductor parameters and as a result it limited the efficiency [8][9].…”

Section: Introductionmentioning

confidence: 96%

“…Khelifi et al [6] investigated the effect of traps on P3HT: PCBM organic solar cells. They defined the presence two defects above the HOMO level of the polymer .They demonstrated that these traps contribute to increase a p-type doping in the active layer and have a strong effect on the charge transport and on the solar cell performance when they are present with a high concentration.…”

Section: Introductionmentioning

confidence: 99%

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Effect of trapping and temperature on the performance of P3HT: PCBM organic solar cells

Taibi¹,

Belghachi

Abid³

2016

Optik

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supporting

confidence: 65%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of trapping and temperature on the performance of P3HT: PCBM organic solar cells

Taibi¹,

Belghachi

Abid³

2016

Optik

Self Cite

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“…We utilised capacitance-voltage measurements in the dark to determine the degree to which a depletion region is present in the active layer. Capacitance-voltage measurements are an established technique used to determine the doping density of a semiconductor 6,19,29,38,[41][42][43] . The width of the space-charge region is probed by a variation of the DC voltage and is detected by measuring the capacitance of the device as a function of the DC voltage.…”

Section: Resultsmentioning

confidence: 99%

“…The capacitance is proportional to (V-V BI ) 21/2 . Thus, we analyzed the data using the Mott-Schottky analysis leading to dopant densities of N A < 4 3 10 16 cm 23 of an excess of positive carriers in both devices (shown in SI Fig S4) 41 . This is a relatively high dopant concentration and thus space-charge effects will be playing a part in carrier extraction.…”

Section: Resultsmentioning

confidence: 99%

Influence of doping on charge carrier collection in normal and inverted geometry polymer:fullerene solar cells

Dibb

Muth

Kirchartz

et al. 2013

Sci Rep

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While organic semiconductors used in polymer:fullerene photovoltaics are generally not intentionally doped, significant levels of unintentional doping have previously been reported in the literature. Here, we explain the differences in photocurrent collection between standard (transparent anode) and inverted (transparent cathode) low band-gap polymer:fullerene solar cells in terms of unintentional p-type doping. Using capacitance/voltage measurements, we find that the devices exhibit doping levels of order 10 16 cm 23 , resulting in space-charge regions ,100 nm thick at short circuit. As a result, low field regions form in devices thicker than 100 nm. Because more of the light is absorbed in the low field region in standard than in inverted architectures, the losses due to inefficient charge collection are greater in standard architectures. Using optical modelling, we show that the observed trends in photocurrent with device architecture and thickness can be explained if only charge carriers photogenerated in the depletion region contribute to the photocurrent.T he record power conversion efficiency (PCE) achieved by polymer:fullerene solar cells has increased considerably in the past 4 years to a record published value of 9.2% 1 for a single bulk heterojunction and efficiencies of 10.6% for tandem solar cells 2 . This is despite the fact that organic semiconductors are known to be both structurally and electronically disordered, have lower dielectric constants inhibiting separation of the photogenerated excitonic species and have charge carrier mobilities orders of magnitude lower than inorganic semiconductors.Whilst charge mobilities are low in organic semiconductors and collection losses have been shown to limit the fill factor (FF) 3-5 and short circuit current density (J SC ) 6-10 of certain devices, low mobilities do not necessarily prevent devices from performing efficiently. However the lower charge mobilities and diffusion coefficients in organic semiconductors do mean that diffusion alone is insufficient for charge carrier collection and drift must account for a large proportion of the generated photocurrent. Additionally, polymer:fullerene solar cells are not intentionally doped like their inorganic counterparts or like many small molecule solar cells 11 and therefore rely on selective contacts and the difference in work function between electrodes for efficient charge collection. However, several studies have found evidence for unintentional doping [12][13][14][15][16][17][18][19] and discussed the consequences for device behaviour 6,[20][21][22][23][24][25][26][27][28][29][30] . Whilst the origin of this doping is unclear 15 , its effects on photovoltaic performance can be substantial; however many recent analyses of device performance neglect doping 8,[31][32][33] despite the fact that the influence of doping and the electric field on charge carrier collection is well known for a long time 34 and wellstudied for instance in the field of quantum dot photovoltaics 35,36 .In this paper, we address the...

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2023

Defects in Organic Semiconductors and Devices

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Investigation of defects by admittance spectroscopy measurements in poly (3-hexylthiophene):(6,6)-phenyl C61-butyric acid methyl ester organic solar cells degraded under air exposure

Cited by 123 publications

References 34 publications

Effect of trapping and temperature on the performance of P3HT: PCBM organic solar cells

Effect of trapping and temperature on the performance of P3HT: PCBM organic solar cells

Influence of doping on charge carrier collection in normal and inverted geometry polymer:fullerene solar cells

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