Effects of C70 derivative in low band gap polymer photovoltaic devices: Spectral complementation and morphology optimization

Yao, Yan; Shi, Chenjun; Li, Gang; Shrotriya, Vishal; Pei, Qibing; Yang, Yang

doi:10.1063/1.2361082

Cited by 112 publications

(80 citation statements)

References 28 publications

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“…The surface of the ITO substrate was modified by spin-coating conducting PEDOT:PSS (Baytron P VP A1 4083) with a thickness of around 40 nm, followed by baking at 150 8C for 15 min in ambient air. BisEH-PFDTBT and BisDMO-PFDTBT were blended with PC 71 BM and dissolved in 1,2-dichlorobenzene (DCB) due to the better solubility of PC 71 BM in DCB than in chlorobenzene (CB) [19]. The best device performance of each polymer was achieved when both of the mixed solutions had a polymer:PC 71 Figure 3 was spin-coated according to the optimal condition of P3HT/PC 61 BM in 1:1 w/w ratio, dissolved in DCB, as reported in ref.…”

Section: Methodsmentioning

confidence: 99%

“…[18,19] Photoluminescence quenching of both polymer blends was observed when PC 71 BM was blended with BisEH-PFDTBT and BisDMO-PFDTBT individually, suggesting efficient charge transfer from the polymer donor to PC 71 BM. Atomic force microscopy (AFM) images show that the active layer of a 2 mm Â 2 mm surface area sample has a root-mean-square (rms.)…”

Section: à2mentioning

confidence: 97%

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Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk Heterojunctions

et al. 2009

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Polymer solar cells have evolved as a promising costeffective alternative to inorganic-based solar cells [1,2] due to their potential to be low-cost, light-weight, and flexible. Since the discovery of ultrafast photoinduced charge transfer from a conjugated polymer to fullerene molecules, followed by the introduction of the bulk heterojunction (BHJ) concept, [3] intensive research with potential materials has been carried out as future photovoltaic (PV) technology. [4][5][6][7][8] Two organic materials with distinct donor and acceptor properties are required to form a heterojunction in the bulk film, which is often achieved by solution processing. In such a case, the BHJ not only provides abundant donor/acceptor interfaces for charge separation, but also forms an interpenetrating network for charge transport. [8,9] Highly efficient polymer solar cells based on poly(3-hexylthiosphene) (P3HT) and [6,6]-phenyl C 61 butyric acid methyl ester (PC 61 BM) have been reported with power conversion efficiencies of 4-5%. [6,[10][11][12] The two most decisive parameters regarding polymer-solar-cell efficiencies are the open-circuit voltage (V oc ) and the short-circuit current (J sc ). J sc is mostly determined by the light absorption ability of the material, the charge-separation efficiency, and the high and balanced carrier mobilities. On the other hand, V oc is limited by the difference in the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor, where a small V oc (as compared to the photon energy) represents a smaller driving force for the PV process. For the P3HT:PC 61 BM system, the V oc is around 0.6 V, which significantly limits the overall device efficiency. An effective method to improve the V oc of polymer solar cells is to manipulate the HOMO level of the donor and/or LUMO level of the acceptor.[13] Until now, fullerene derivatives have proved to be one of the best and most commonly used electron acceptors. Fortunately, it is convenient to change the band gap and energy levels of the donor material by modifying the chemical structure to achieve a high V oc . [13,14] Amongst various polymers, poly{[2,7-(9-(20-ethylhexyl)-9-hexylfluorene])-alt- [5,50-(40, 70-di-2-thienyl-20,10,30-benzothiadiazole)]} (PFDTBT) has a deep HOMO level, which leads to a large V oc when blended with PC 61 BM. Svensson et al. [15] have reported polymer PV cells with a V oc of 1 V based on alternating copolymer PFDTBT blended with PC 61 BM. Moreover, Inganäs et al.[16] reported a systematic study of PV cells using four different fluorene copolymers by varying the length of the alkyl side chain and chemical structure, exhibiting power conversion efficiencies above 2-3%. Unfortunately, in their case, the low photocurrent becomes a major limiting factor in achieving higher efficiencies, suggesting low carrier mobilities.In this study, poly{[2,7-(9,9-bis-(2-ethylhexyl)-fluorene)]-alt-[5,5-(4,7-di-2 0 -thienyl-2,1,3-benzothiadiazole)]} (BisEH-PFDTBT) and poly{[2,7-(9,9-bis-(3,...

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Section: Methodsmentioning

confidence: 99%

Section: à2mentioning

confidence: 97%

Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk Heterojunctions

et al. 2009

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“…roughness of 0.8 nm) and negligible phase contrast, indicating uniform distribution of the mixture. [25] However, CB produced much rougher films (r.m.s. roughness 4.0 nm) and visible phase separation of 200-300 nm.…”

Section: Effect Of Solventsmentioning

confidence: 99%

Recent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar Cells

et al. 2009

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Polymer morphology has proven to be extremely important in determining the optoelectronic properties in polymer‐based devices. The understanding and manipulation of polymer morphology has been the focus of electronic and optoelectronic polymer‐device research. In this article, recent advances in the understanding and controlling of polymer morphology are reviewed with respect to the solvent selection and various annealing processes. We also review the mixed‐solvent effects on the dynamics of film evolution in selected polymer‐blend systems, which facilitate the formation of optimal percolation paths and therefore provide a simple approach to improve photovoltaic performance. Recently, the occurrence of vertical phase separation has been found in some polymer:fullerene bulk heterojunctions.1–3 The origin and applications of this inhomogeneous distribution of the polymer donor and fullerene acceptor are addressed. The current status and device physics of the inverted structure solar cells is also reviewed, including the advantage of utilizing the spontaneous vertical phase separation, which provides a promising alternative to the conventional structure for obtaining higher device performance.

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“…This distinction was also manifested in the absorption spectra of the blend fi lms (Figure 3 b), which can be ascribed to the fact that PC 71 BM possesses better light absorption in the visible region compared to that of PC 61 BM. [ 11 ] It is worthy noting that both Device A and Device B possessed high FF values (>65%), as shown in Table 1 . The reason Table 1 for descriptions of the device types).…”

Section: Single-junction Solar Cellsmentioning

confidence: 94%

“…[ 8,9 ] Additionally, although most of the high-performance single-junction devices reported to date are based on medium bandgap polymers ( E g ≈ 1.6 eV), [ 10 ] their utilization in tandem cells remains quite challenging because their absorption have signifi cant overlap with other commonly used polymers. [ 10 ] Considering that PC 61 BM and PC 71 BM possess different absorption characteristics in the visible region, [ 11 ] the combination of a medium bandgap polymer with PC 61 BM and PC 71 BM as the active layer would be an promising approach to realize the complementary absorption characteristics.…”

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confidence: 99%

Highly Efficient Polymer Tandem Cells and Semitransparent Cells for Solar Energy

Chang

Zuo

Yip

et al. 2013

Advanced Energy Materials

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Highly efficient tandem and semitransparent (ST) polymer solar cells utilizing the same donor polymer blended with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) as active layers are demonstrated. A high power conversion efficiency (PCE) of 8.5% and a record high open‐circuit voltage of 1.71 V are achieved for a tandem cell based on a medium bandgap polymer poly(indacenodithiophene‐co‐phananthrene‐quinoxaline) (PIDT‐phanQ). In addition, this approach can also be applied to a low bandgap polymer poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7‐(5‐fluoro‐2,1,3‐benzothia‐diazole)] (PCPDTFBT), and PCEs up to 7.9% are achieved. Due to the very thin total active layer thickness, a highly efficient ST tandem cell based on PIDT‐phanQ exhibits a high PCE of 7.4%, which is the highest value reported to date for a ST solar cell. The ST device also possesses a desirable average visible transmittance (≈40%) and an excellent color rendering index (≈100), permitting its use in power‐generating window applications.

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Effects of C70 derivative in low band gap polymer photovoltaic devices: Spectral complementation and morphology optimization

Cited by 112 publications

References 28 publications

Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk Heterojunctions

Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk Heterojunctions

Recent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar Cells

Highly Efficient Polymer Tandem Cells and Semitransparent Cells for Solar Energy

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