Effect of SWNT Defects on the Electron Transfer Properties in P3HT/SWNT Hybrid Materials

Geng, Jianxin; Kong, Byung-Seon; Yang, Seung Bo; Youn, Sang Cheon; Park, Sohyun; Joo, Taiha; Jung, Hee‐Tae

doi:10.1002/adfm.200800496

Cited by 102 publications

(93 citation statements)

References 55 publications

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“…Moreover, the absorption of hybrid film exhibits obvious red-shift derived from the reciprocity of the two components. [37][38][39] The hybrid photodetector device was fabricated and measured as previously reported, 8,40 which exhibits excellent photoresponse characteristics as shown in Figure 3b. When the light irradiation was turned on and off, the current output of the device exhibits two distinct states, a 'low' current in the dark and a 'high' current under illumination.…”

Section: Resultsmentioning

confidence: 99%

Wurtzite Cu2ZnSnSe4 nanocrystals for high-performance organic–inorganic hybrid photodetectors

2012

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Indium-free quaternary chalcogenide, Cu 2 ZnSnSe 4 (CZTSe), has driven much attention for its potential application in photovoltaics and optoelectronics. It is well known that the composition and structure of nanocrystals (NCs) significantly affect their optical and electrical properties. Controllable synthesis of materials with new crystal structures, especially metastable structures, has given impetus to the development of nanomaterials with many new exciting properties and applications. Highquality CZTSe NCs with thermodynamically metastable wurtzite phase and optical band gap of 1.46 eV were herein synthesized via a facile, lost-cost and safe-solution method. The formation mechanism of the wurtzite CZTSe NCs was investigated in detail, which indicates high reaction rate and low surface energy are favorable for the formation of wurtzite structure. The promising application of as-synthesized NCs in photovoltaics and optoelectronics has been demonstrated by the high-performance hybrid photodetector made from CZTSe NCs and P3HT, with an on/off ratio larger than 150.

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Section: Resultsmentioning

confidence: 99%

Wurtzite Cu2ZnSnSe4 nanocrystals for high-performance organic–inorganic hybrid photodetectors

2012

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“…This is the first time such blends have been studied using femtosecond time resolution, and we observe a charge transfer time three-magnitudes faster than reported previously. 17,18 In addition, significant long-term charge separation is observed for the first time in SWNTpolymer blends. We conclude that charge separation is only possible if small-diameter semiconducting tubes are individually embedded in an excess P3HT matrix.…”

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confidence: 99%

Ultrafast Charge Separation at a Polymer−Single-Walled Carbon Nanotube Molecular Junction

et al. 2010

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We have investigated the charge photogeneration dynamics at the interface formed between single-walled carbon nanotubes (SWNTs) and poly(3-hexylthiophene) (P3HT) using a combination of femtosecond spectroscopic techniques. We demonstrate that photoexcitation of P3HT forming a single molecular layer around a SWNT leads to an ultrafast (∼430 fs) charge transfer between the materials. The addition of excess P3HT leads to long-term charge separation in which free polarons remain separated at room temperature. Our results suggest that SWNT-P3HT blends incorporating only small fractions (1%) of SWNTs allow photon-to-charge conversion with efficiencies comparable to those for conventional (60:40) P3HT-fullerene blends, provided that small-diameter tubes are individually embedded in the P3HT matrix.KEYWORDS Carbon nanotube, P3HT, charge separation, molecular junction O rganic photovoltaic (OPV) cells have been demonstrated as low-cost alternatives to silicon-based cells, offering the possibility of low temperature "reel-to-reel" fabrication, necessary for viable large-scale power generation.1 The majority of OPV devices utilize exciton dissociation at the interface between two materials which exhibit a type-II heterojunction alignment, 2 resulting in interfacial charge separation and free polarons in the materials. However, it has been shown that for many OPV materials such as polymer-polymer blends, exciton dissociation leads to the formation of an interfacial bound geminate charge pair, termed an exciplex. [3][4][5][6][7] This species can be strongly bound and long-lived, significantly lowering charge separation efficiencies. studies demonstrating that a type-II heterojunction only exists for certain interfaces, such as between small diameter semiconducting SWNTs and regioregular poly(3-hexylthiophene) (P3HT). Even for such blends, energy transfer from the polymer to the SWNTs may compete effectively against charge transfer.In this letter, we show that charge transfer across the interface between individually dispersed SWNTs wrapped in a monolayer sheath of P3HT occurs on an ultrafast (430 fs) time scale. Generated charge pairs relax into a bound interfacial charge-transfer state or via nonradiative recombination of excitons within the nanotubes and no long-lived free polarons are observed. However, in the presence of an excess P3HT network, charge separation at room temperature is long-lived and comparable to that in a conventional P3HT-fullerene blend. This is the first time such blends have been studied using femtosecond time resolution, and we observe a charge transfer time three-magnitudes faster than reported previously. 17,18 In addition, significant long-term charge separation is observed for the first time in SWNTpolymer blends. We conclude that charge separation is only possible if small-diameter semiconducting tubes are individually embedded in an excess P3HT matrix. Our findings explain the poor polymer-SWNT device behavior to date and provide a promising route to incorporation of SWNTpolymer blen...

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“…CNTs can be a direct path of charge transport to the electrode and can be used as the electron acceptor [34,35]. This observation also explains the CNTs substitute in place of PCBM and serves efficiently as electron transport through ballistic pathways instead of by slow hopping and tunnelling among phase separated clusters as the case for QD -only devices [26][27][28][29][30].…”

Section: -P3mentioning

confidence: 89%

“…The other main feature is; the semiconducting PbS colloidal QDs (in the QD/MWCNT nanohybrids) served as donors for the electron-accepting PCBMs. The charge transport was also further efficiently assisted by the presence of CNTs due to their dual electronic nature since the CNTs can either be preferentially employed as a donor -or acceptor -type materials [34,35]. This is consistent with the band diagram shown in Figure 7 and with aid of this band diagram we able to explain that the excitons generated in PbS-QDs in the NIR region, can be dissociated at the PbS/MWCNT interface to yield photocurrent in the external circuit.…”

Section: -P3mentioning

confidence: 99%

Enhanced photovoltaic conversion efficiency in bulk heterojunction solar cells upon incorporating nanohybridized PbS quantum dots/multiwall carbon nanotubes

Baral

Sharma

Wang

et al. 2014

Eur. Phys. J. Appl. Phys.

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Abstract. We report on a modified bulk heterojunction (BHJ) solar cell in which a nanohybridized composition of lead sulfide (PbS) colloidal quantum dots (QDs) and multiwall carbon nanotubes (MWCNTs) were incorporated into a standard regioregular poly(3-hexylthiophene) (rr-P3HT):phenyl-C61-butyric acid methyl ester (PCBM) blend. This hybrid ((P3HT:PCBM):PbS-QD/MWCNT) solar cell exhibits an increased power conversion efficiency (PCE) of 3.40% as compared to that of 2.57% from a controlled P3HT:PCBM standard BHJ solar cell fabricated under similar experimental conditions. The 32% increase in efficiency is effectively attributed to the extended quantum-dot-sensitization in the near-infrared (NIR) due to the absorbance of QDs/CNTs in the spectral range from 700 nm to 1450 nm. The strong conjugation, controlled coupling and nanohybridization of QDs/CNTs played an important role towards the improvement of PCE since it is proposed that excitons generated in the QDs can be efficiently dissociated at the QD/CNT interface by transferring the electrons to the CNTs followed by holes transfer to the P3HT. In this ternary blend, the staggered energy band alignment between P3HT and the QDs allows both electrons and holes transfer from the QDs to the PCBM and the P3HT, respectively. Subsequently, the dissociated carriers have been efficiently transported by the CNTs and P3HT to favorable respective electrodes.

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Effect of SWNT Defects on the Electron Transfer Properties in P3HT/SWNT Hybrid Materials

Cited by 102 publications

References 55 publications

Wurtzite Cu2ZnSnSe4 nanocrystals for high-performance organic–inorganic hybrid photodetectors

Wurtzite Cu2ZnSnSe4 nanocrystals for high-performance organic–inorganic hybrid photodetectors

Ultrafast Charge Separation at a Polymer−Single-Walled Carbon Nanotube Molecular Junction

Enhanced photovoltaic conversion efficiency in bulk heterojunction solar cells upon incorporating nanohybridized PbS quantum dots/multiwall carbon nanotubes

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