Morphologies of Self-Organizing Regioregular Conjugated Polymer/Fullerene Aggregates in Thin Film Solar Cells

Chiu, Mao-Yuan; Jeng, U‐Ser; Su, Ming-Shin; Wei, Kung‐Hwa

doi:10.1021/ma901895d

Cited by 124 publications

(116 citation statements)

References 36 publications

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“…We attribute the broad maximum located between values of q at 1.3 and 1.6 Å −1 , with a maximum around q = 1.45 Å −1 to the scattering from PC 61 BM; [ 22 ] this hump intensifi es and sharpens slightly upon increasing the PC 61 BM content in the blend thin fi lms. [ 23 ] Besides the effect of fi lm thickness from various ratios, relative refl ection peak intensities from X2 and PC 61 BM correspond to the respective mixing ratios showing the expected predominance of the abundant species. The full width at half maximum (FWHM) of the π−π (in-plane) and alkyl chain (out of plane) stacking peaks of X2 crystallites and the Scherrer equation were used to obtain the CCL.…”

Section: Wileyonlinelibrarycommentioning

confidence: 96%

Structural Characterization of a Composition Tolerant Bulk Heterojunction Blend

Huang

Liu

Wang

et al. 2014

Advanced Energy Materials

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Extensive internal electron donor (D)/ acceptor (A) interfaces promote charge separation, while the D and A domains lead to effi cient charge carrier transport. Also worth noting is that the components' domain size should be commensurate with the exciton diffusion length and delocalization (≈10 nm) [ 4 ] to maximize charge generation. [ 5 ] The detailed morphology of the donor and acceptor domains within the BHJ material is therefore a principal factor for effi cient charge generation in the fi lm and current collection to the external circuit.Many cases studied in the past tell us that the performance of an organic photovoltaic device fabricated from blends of D and A can depend strongly on the relative amounts of the components and therefore the D:A blend ratio is an important para meter to optimize the device efficiency. For example, bld ratios signifi cantly infl uence the power conversion effi ciency (PCE) of small molecule organic solar cell, such as the 5,5′-bis-3,3′-di-2-ethylhexylsilylene-2,2′-bithiophene (DTS(PTTh 2 ) 2 )/[6,6]-phenyl C71 butyric acid methyl ester (PC 71 BM) system, [ 6 ] for which, when deposited from neat solvent one observes changes in PCE from 4.5% at 7:3, to 3.6% at 8:2 or 2.1% at 6:4. PCE values can also be acutely dependent on the blend ratio with conjugated polymer systems. [ 7,8 ] For example, PIDTDTQx/PC 71 BM system shows highest PCE at a 1:4 blend ratio, increasing or decreasing PCBM loading level reduced its PCE to a large extent. [ 7 ] Its PCE is reduced from 7.5% to 4.2% when the weight fraction of PC 71 BM drops from 80% to 66%. Park et al. showed that the connectivity of each phase is sensitive to the blend ratios of poly[N-9′′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) to PC 71 BM. The fi brillar PCDTBT nanostructure becomes clear and well-defi ned at a PC 71 BM content of 80 wt%. [ 9 ] Interestingly, it was found that the performance of the welldefi ned molecule X2 ( Scheme 1 ) with PC 61 BM was relatively insensitive, relative to changes in blend ratio. A similar compositional independence was also found in PTB1/PC 71 BM polymer system, [ 10 ] whose PCE did change by only 0.3% from 7:3 to 5:5 blend ratio. In addition, small molecule DPP(THFu) 2 / PC 71 BM system exhibits a similar compositional tolerance from 7:3 to 5:5 blend ratio. [ 11 ] Despite the obvious advantages of such BHJ systems for tolerating errors during high throughput massThe ratio of the donor and acceptor components in bulk heterojunction (BHJ) organic solar cells is a key parameter for achieving optimal power conversion effi ciency (PCE). However, it has been recently found that a few BHJ blends have compositional tolerance and achieve high performance in a wide range of donor to acceptor ratios. For instance, the X2 :PC 61 BM system, where X2 is a molecular donor of intermediate dimensions, exhibits a PCE of 6.6%. Its PCE is relatively insensitive to the blend ratio over the range from 7:3 to 4:6. The effect of blend ratio of X2 /PC 61 BM on morphol...

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Section: Wileyonlinelibrarycommentioning

confidence: 96%

Structural Characterization of a Composition Tolerant Bulk Heterojunction Blend

Huang

Liu

Wang

et al. 2014

Advanced Energy Materials

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“…From the scattering pattern of (100), we extracted a d -spacing of 1.59 nm, which is consistent with data reported elsewhere. [ 21 ] The P3HT crystallite results. [ 30 ] Adding PS-b -P3HT copolymer in different fractions, however, induced the changes in the SLD distribution in the fi lms.…”

Section: Doi: 101002/adma201103361mentioning

confidence: 99%

PS‐b‐P3HT Copolymers as P3HT/PCBM Interfacial Compatibilizers for High Efficiency Photovoltaics

et al. 2011

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“…Due to enhanced and balanced charge conduction in the roller-painted P3HT/PCBM film, a high FF of 0.64 was achieved. [41] When the nanoscale morphology of the active layer is examined by TEM, the roller-painted film exhibits an interesting morphology, as shown in Figure 6a. Very dark, cilia-like nanocrystals (width ca.…”

Section: Full Papermentioning

confidence: 99%

Annealing‐Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting Process

Jung

2010

Adv Funct Materials

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Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller‐painted film – composed of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) – has a smoother surface than a spin‐coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller‐painted active layer contribute to enhanced and balanced charge‐carrier mobility. Consequently, the roller‐painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing‐free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi‐1,8‐thiol. Since the addition of octanedi‐1,8‐thiol induces phase separation between P3HT and PCBM and the roller‐painting process induces crystallization of P3HT and PCBM, a PCE of roller‐painted PSCs of up to 3.8% is achieved without post‐annealing. A PCE of over 2.7% can also be achieved with 5 cm2 of active area without post‐annealing.

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Morphologies of Self-Organizing Regioregular Conjugated Polymer/Fullerene Aggregates in Thin Film Solar Cells

Cited by 124 publications

References 36 publications

Structural Characterization of a Composition Tolerant Bulk Heterojunction Blend

Structural Characterization of a Composition Tolerant Bulk Heterojunction Blend

PS‐b‐P3HT Copolymers as P3HT/PCBM Interfacial Compatibilizers for High Efficiency Photovoltaics

Annealing‐Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting Process

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