Analysis of Charge Photogeneration as a Key Determinant of Photocurrent Density in Polymer: Fullerene Solar Cells

Clarke, Tracey M.; Ballantyne, Amy M.; Shoaee, Safa; Soon, Ying Woan; Duffy, Warren; Heeney, Martin; McCulloch, Iain; Nelson, Jenny; Durrant, James R.

doi:10.1002/adma.201002357

Cited by 64 publications

(77 citation statements)

References 18 publications

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“…It has been previously established that the ∆OD at 1 µs of a polymer:PCBM blend film is directly correlated with the J SC of the resultant photovoltaic device. [38] According to this correlation, the small drop in ∆OD upon photodegradation would cause a reduction in the J SC of approximately 0.5 mA cm -2 . The decrease in J SC observed in KP115:PCBM upon photodegradation is almost four times more than this.…”

Section: Steady State and Transient Absorption Spectroscopymentioning

confidence: 93%

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Clarke

Lungenschmied²,

Peet³

et al. 2013

Advanced Energy Materials

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. (2013). Photodegradation in encapsulated silole-based polymer: Pcbm solar cells investigated using transient absorption spectroscopy and charge extraction measurements. Advanced Energy Materials, 3 (11), 1473-1483. Photodegradation in encapsulated silole-based polymer: Pcbm solar cells investigated using transient absorption spectroscopy and charge extraction measurements AbstractLight induced degradation has been observed in the performance of organic solar cells in the absence of oxygen and a detailed analysis of the effect of this photodegradation on optical and electrical features has been accomplished. This photodegradation study has been performed on encapsulated photovoltaic blend devices comprised of the silole-based donor-acceptor polymer KP115 blended with [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Photodegradation induces an almost 20% decrease in power conversion efficiency, primarily as a result of a reduction in short circuit current, JSC. The initial burn-in phase of the photodegradation has been examined using a combination of transient absorption spectroscopy and charge extraction measurements, including photo-CELIV (charge extraction by linearly increasing voltage) and timeresolved charge extraction using a nanosecond switch. These measurements reveal a bimodal KP115 polaron population, comprised of both delocalised and localised/trapped charge carriers. The photodegradation results are consistent with an alteration of this bimodal KP115 polaron population, with the polarons becoming trapped in a broader, deeper density of localised states. Under laser illumination and at open circuit conditions, this enhanced trapping after light soaking inhibits charges from undergoing bimolecular recombination, leading to higher extracted charge densities at long times. At the lower charge densities operating at short circuit conditions and under continuous white light illumination, where bimolecular recombination is much less significant, the JSC decreases after light soaking due to a reduction in the efficiency of trapped charge carrier extraction. Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsClarke, T. M., Lungenschmied, C., Peet, J., Drolet, N., Sunahara, K., Furube, A. & Mozer, A. J. (2013

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Section: Steady State and Transient Absorption Spectroscopymentioning

confidence: 93%

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Clarke

Lungenschmied²,

Peet³

et al. 2013

Advanced Energy Materials

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“…Consequently, it is being investigated intensely. [2][3][4][5][6][7][8][9][10][11] There is widespread agreement on the elementary steps that accompany charge carrier generation at an organic molecular heterojunction. [1,12] Light absorption creates an excited state on one molecule.…”

Section: Doi: 101002/adma201104063mentioning

confidence: 99%

Does Conjugation Help Exciton Dissociation? A Study on Poly(p‐phenylene)s in Planar Heterojunctions with C₆₀ or TNF

et al. 2012

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“…We have previously reported a clear correlation between device photocurrent and the amplitude of the power law transient absorption decay phase, assigned to the photoinduced absorption of dissociated charge carriers in the blend fi lms, for a range of donor polymers blended with PC 60 BM and PC 70 BM. [ 45 ] The result of this analysis for the fullerene:polymer set studied herein is shown in Figure 6 . It is striking that for the blends studied herein we observe a good correlation between the amplitude of our power-law decay phase and J SC .…”

Section: Photophysical Analyses Of Charge Photogenerationmentioning

confidence: 99%

Charge Photogeneration for a Series of Thiazolo‐Thiazole Donor Polymers Blended with the Fullerene Electron Acceptors PCBM and ICBA

Shoaee

Subramaniyan

Xin

et al. 2013

Adv Funct Materials

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Photoinduced charge separation in bulk heterojunction solar cells is studied using a series of thiazolo‐thiazole donor polymers that differ in their side groups (and bridging atoms) blended with two acceptor fullerenes, phenyl‐C71‐butyric acid methyl ester (PC71BM) and a fullerene indene‐C60 bisadduct (ICBA). Transient absorption spectroscopy is used to determine the yields and lifetimes of photogenerated charge carriers, complimented by cyclic voltammetry studies of materials energetics, wide angle X‐ray diffraction and transmission electron microscopy studies of neat and blend film crystallinity and photoluminescence quenching studies of polymer/fullerene phase segregation, and the correlation of these measurements with device photocurrents. Good correlation between the initial polaron yield and the energetic driving force driving charge separation, ΔECS is observed. All blend films exhibit a power law transient absorption decay phase assigned to non‐geminate recombination of dissociated charges; the amplitude of this power law decay phase shows excellent correlation with photocurrent density in the devices. Furthermore, for films of one (relatively amorphous) donor polymer blended with ICBA, we observe an additional 100 ns geminate recombination phase. The implications of the observations reported are discussed in terms of the role of materials' crystallinity in influencing charge dissociation in such devices, and thus materials design requirements for efficient solar cell function.

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Analysis of Charge Photogeneration as a Key Determinant of Photocurrent Density in Polymer: Fullerene Solar Cells

Cited by 64 publications

References 18 publications

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Does Conjugation Help Exciton Dissociation? A Study on Poly(p‐phenylene)s in Planar Heterojunctions with C₆₀ or TNF

Charge Photogeneration for a Series of Thiazolo‐Thiazole Donor Polymers Blended with the Fullerene Electron Acceptors PCBM and ICBA

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Analysis of Charge Photogeneration as a Key Determinant of Photocurrent Density in Polymer: Fullerene Solar Cells

Cited by 64 publications

References 18 publications

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Photodegradation in Encapsulated Silole‐Based Polymer: PCBM Solar Cells Investigated using Transient Absorption Spectroscopy and Charge Extraction Measurements

Does Conjugation Help Exciton Dissociation? A Study on Poly(p‐phenylene)s in Planar Heterojunctions with C60 or TNF

Charge Photogeneration for a Series of Thiazolo‐Thiazole Donor Polymers Blended with the Fullerene Electron Acceptors PCBM and ICBA

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Product

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Does Conjugation Help Exciton Dissociation? A Study on Poly(p‐phenylene)s in Planar Heterojunctions with C₆₀ or TNF