Effect of Polymer Crystallinity in P3HT:PCBM Solar Cells on Band Gap Trap States and Apparent Recombination Order

Spoltore, Donato; Oosterbaan, Wibren D.; Khelifi, Samira; Clifford, John N.; Viterisi, Aurélien; Palomares, Emilio; Burgelman, Marc; Lutsen, Laurence; Vanderzande, Dirk; Manca, Jean

doi:10.1002/aenm.201200674

Cited by 49 publications

(52 citation statements)

References 46 publications

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“…One of the few exceptions is poly (3hexylthiophene): [6,6]-phenyl-C61-butyric acid (P3HT:PCBM), for which moderately high effi ciencies and FF s of close to and above 0.6 have been seen with active layers up to 300 nm in thickness. [23][24][25] In addition, geminate recombination might negatively affect photogeneration effi ciency and in some cases the thickness dependence, if the microstructure is unsuitable for effi cient charge carrier generation. For many highly effi cient organic solar cells, non-geminate recombination has been identifi ed as the primary loss process that controls photocurrent generation.…”

Section: The Poor Photovoltaic Performance Of State-of-the-art Blendsmentioning

confidence: 99%

Electron Collection as a Limit to Polymer:PCBM Solar Cell Efficiency: Effect of Blend Microstructure on Carrier Mobility and Device Performance in PTB7:PCBM

Foster

Deledalle

Mitani

et al. 2014

Advanced Energy Materials

162

143

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The poor photovoltaic performance of state‐of‐the‐art blends of poly[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl] (PTB7) and [6,6]‐phenyl‐C61‐butyric acid (PCBM) at large active layer thicknesses is studied using space‐charge‐limited current mobility and photovoltaic device measurements. The poor performance is found to result from relatively low electron mobility. This is attributed to the low tendency of PTB7 to aggregate, which reduces the ability of the fullerene to form a connected network. Increasing the PCBM content 60–80 wt% increases electron mobility and accordingly improves performance for thicker devices, resulting in a fill factor (FF) close to 0.6 at 300 nm. The result confirms that by improving only the connectivity of the fullerene phase, efficient electron and hole collection is possible for 300 nm‐thick PTB7:PCBM devices. Furthermore, it is shown that solvent additive 1,8‐diiodooctane (DIO), used in the highest efficiency PTB7:PCBM devices, does not improve the thickness dependence and, accordingly, does not lead to an increase in either hole or electron mobility or in the carrier lifetime. A key challenge for researchers is therefore to develop new methods to ensure connectivity in the fullerene phase in blends without relying on either a large excess of fullerene or strong aggregation of the polymer.

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Section: The Poor Photovoltaic Performance Of State-of-the-art Blendsmentioning

confidence: 99%

Electron Collection as a Limit to Polymer:PCBM Solar Cell Efficiency: Effect of Blend Microstructure on Carrier Mobility and Device Performance in PTB7:PCBM

Foster

Deledalle

Mitani

et al. 2014

Advanced Energy Materials

162

143

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“…12,22,32 Detailed values of λ and corresponding discussions are shown in the Supporting Information (Table S1). Figure 2a demonstrates the k rec under varying illumination intensities for the three different polymer donor devices.…”

Section: Resultsmentioning

confidence: 99%

Structural Order: The Dominant Factor for Nongeminate Recombination in Organic Photovoltaic Devices

Wang

Hsu

2017

J. Phys. Chem. C

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Reducing nongeminate recombination (NGR) will provide a major boost to the performance of bulk heterojunction (BHJ) organic photovoltaic (OPV) devices. It is therefore critical to identify the dominant factor(s) that determines NGR. While substantial research effects have been made and various factors have been considered, the determining factor has not been ascertained. After comprehensively evaluating the impact of deep defect states, donor−acceptor interfacial area, and mobility, here we demonstrate that the structural order is the dominant factor that determines NGR in OPV devices. Intensity modulated photovoltage spectroscopy in conjunction with the charge extraction technique is applied to quantitatively measure bimolecular recombination coefficients. A model P3HT:PCBM system with varying composition and annealing temperature, which removes uncontrolled variables yet resembles the behaviors of different polymer donor OPV systems, enables us to reach the unambiguous conclusion. Our findings shed light on key strategies to reduce NGR and pave the road for future high performance OPV design and optimization.

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“…Recently, a recombination rate higher than two has been reported in P3HT:PCBM and was linked to a delayed trap assisted recombination process via a tail of trapped states in the gap .…”

Section: Theorymentioning

confidence: 99%

Influence of charge carrier mobility and surface recombination velocity on the characteristics of P3HT:PCBM organic solar cells

Hacène

Benouaz

2014

Physica Status Solidi (a)

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, Phone/Fax: þ213 43 21 59 99The effect of charge carrier mobility and surface recombination velocity has been extensively investigated for poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) organic solar cells. We used the effective medium model and the solar cell simulator (SCAPS) to model the current-voltage (J-V) characteristic and explore the charge carrier transport in P3HT:PCBM devices. We varied the charge carrier mobility for electrons and holes and surface recombination velocity at the contacts for majority and minority charge carriers, and calculated the solar cell characteristics: efficiency (h), open-circuit-voltage (V oc ), short-circuit current (J sc ) and fill factor (FF). The significances of surface recombination velocity together with charge carriers mobility are calculated and discussed. We found that in general reduced surface recombination velocities at both contacts are very detrimental for organic solar cell performance especially for devices with low charge mobilities.

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Effect of Polymer Crystallinity in P3HT:PCBM Solar Cells on Band Gap Trap States and Apparent Recombination Order

Cited by 49 publications

References 46 publications

Electron Collection as a Limit to Polymer:PCBM Solar Cell Efficiency: Effect of Blend Microstructure on Carrier Mobility and Device Performance in PTB7:PCBM

Electron Collection as a Limit to Polymer:PCBM Solar Cell Efficiency: Effect of Blend Microstructure on Carrier Mobility and Device Performance in PTB7:PCBM

Structural Order: The Dominant Factor for Nongeminate Recombination in Organic Photovoltaic Devices

Influence of charge carrier mobility and surface recombination velocity on the characteristics of P3HT:PCBM organic solar cells

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