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496 results on '"Mhaisalkar, Subodh G."'

109. Hole-Transporting Small Molecules Based on Thiophene Cores for High Efficiency Perovskite Solar Cells

Author

Li, Hairong, Fu, Kunwu, Boix, Pablo P., Wong, Lydia H., Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., Grimsdale, Andrew C., Li, Hairong, Fu, Kunwu, Boix, Pablo P., Wong, Lydia H., Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., and Grimsdale, Andrew C.

Abstract

Two new electron-rich molecules, 2,3,4,5-tetra[4,4'-bis(methoxyphenyl)aminophen-4 ''-yl]-thiophene (H111) and 4,4',5,5'-tetra[4,4'-bis(methoxyphenyl) aminophen-4 ''-yl]-2,2'-bithiophene (H112), which contain thiophene cores with arylamine side groups, are reported. When used as the hole-transporting material (HTM) in perovskite-based solar cell devices, power conversion efficiencies of up to 15.4% under AM 1.5G solar simulation were obtained. This is the highest efficiency achieved with HTMs not composed of 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) and its isomers. Both HTMs, especially H111, have great potential to replace expensive spiro-OMeTAD given their much simpler and less expensive syntheses.

Published
2014
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110. A Simple 3,4-Ethylenedioxythiophene Based Hole-Transporting Material for Perovskite Solar Cells

Author

Li, Hairong, Fu, Kunwu, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., Grimsdale, Andrew C., Li, Hairong, Fu, Kunwu, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., and Grimsdale, Andrew C.

Abstract

We report a novel electron-rich molecule based on 3,4-ethylenedioxythiophene (H101). When used as the hole-transporting layer in a perovskite-based solar cell, the power-conversion efficiency reached 13.8% under AM 1.5G solar simulation. This result is comparable with that obtained using the well-known hole transporting material 2,2,7,7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene (spiro-OMeTAD). This is the first heterocycle-containing material achieving >10% efficiency in such devices, and has great potential to replace the expensive spiro-OMeTAD given its much simpler and cheaper synthesis.

Published
2014
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111. Effect of Formamidinium/Cesium Substitution and PbI2 on the Long-Term Stability of Triple-Cation Perovskites.

Author

Shukla, Shashwat, Shukla, Sudhanshu, Haur, Lew Jia, Dintakurti, Sai S. H., Han, Guifang, Priyadarshi, Anish, Baikie, Tom, Mhaisalkar, Subodh G., and Mathews, Nripan

Subjects
CESIUM compounds, SUBSTITUTION reactions, CHEMICAL stability, PEROVSKITE, CHEMICAL kinetics, X-ray diffraction
Abstract

Altering cation and anion ratios in perovskites has proven an excellent means of tuning the perovskite properties and enhancing the performance. Recently, methylammonium/formamidinium/cesium triple-cation mixed-halide perovskites have demonstrated efficiencies up to 22 %. Similar to the widely explored methylammonium lead halide, excess PbI2 is added to these perovskite films to enhance their performances. The excess PbI2 is known to be beneficial for the performance. However, its impact on stability is less well known. Triple-cation perovskites deploy excess PbI2 up to 8 %. Thus, it is imperative to analyze the role of excess PbI2 in the degradation kinetics. In this study, the amount of PbI2 in the triple-cation perovskite films is varied and the degradation kinetics monitored by X-ray diffraction and optical absorption spectroscopy. The inclusion of excess PbI2 is shown to adversely affect the stability of the material. Faster degradation kinetics are observed for samples with higher PbI2 contents. However, samples with excess PbI2 also showed superior properties such as enhanced grain sizes and better optical absorption. Thus, careful management of the PbI2 quantity is required to obtain better stability and alternative pathways should be explored to achieve better device performance rather than adding excess PbI2. [ABSTRACT FROM AUTHOR]

Published
2017
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117. Lead-Free Halide Perovskite Solar Cells with High Photocurrents Realized Through Vacancy Modulation

Author

Kumar, Mulmudi Hemant, primary, Dharani, Sabba, additional, Leong, Wei Lin, additional, Boix, Pablo P., additional, Prabhakar, Rajiv Ramanujam, additional, Baikie, Tom, additional, Shi, Chen, additional, Ding, Hong, additional, Ramesh, Ramamoorthy, additional, Asta, Mark, additional, Graetzel, Michael, additional, Mhaisalkar, Subodh G., additional, and Mathews, Nripan, additional

Published
2014
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129. Influence of 4-tert-Butylpyridine in DSCs with Co-II/III Redox Mediator

Author

Koh, Teck Ming, Nonomura, Kazuteru, Mathews, Nripan, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., Grimsdale, Andrew C., Koh, Teck Ming, Nonomura, Kazuteru, Mathews, Nripan, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., and Grimsdale, Andrew C.

Abstract

The effect of TBP on Co(II/III) redox electrolyte was examined. Photocurrent of the device can be limited in electrolyte with high TBP concentration due to its viscous nature. The higher amount of TBP in electrolyte increases the viscosity of electrolyte and consequently slows down the diffusion of Co-III species. This is a unique observation for Co(II/III) electrolyte which is not observed in I-/I-3(-) electrolyte. An increase in TBP concentration from 0.1 to 0.5 M in a cobalt electrolyte containing 0.1 M Co(bpy)(3)(TFSI)(2) and 0.033 M Co(bpy)(3)(TFSI)(3) produced a 90 mV improvement in open-circuit potential (V-oc). Using electrochemical impedance spectroscopy (EIS), this enhancement could be attributed to the reduced interfacial recombination (33%) as well as a negative shift in the conduction 0 band level of TiO2 (67%). Although the influence of TBP in iodide/triiodide and cobalt-complex electrolytes is similar, the increase of viscosity at relatively high concentration of TBP in Co electrolyte should be taken into consideration in order to accomplish high efficiency DSCs based on Co-complex electrolytes.

Published
2013
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130. New donor-pi-acceptor sensitizers containing 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione units

Author

Li, Hairong, Koh, Teck Ming, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., Grimsdale, Andrew C., Li, Hairong, Koh, Teck Ming, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., and Grimsdale, Andrew C.

Abstract

Two new D-pi-A sensitizers (L101 and L102) incorporating 5H-[1,2,5]thiadiazolo [3,4-f] isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). L102 achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.5, 100 mW cm(-2)).

Published
2013
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131. Photovoltage enhancement from cyanobiphenyl liquid crystals and 4-tert-butylpyridine in Co(II/III) mediated dye-sensitized solar cells

Author

Koh, Teck Ming, Li, Hairong, Nonomura, Kazuteru, Mathews, Nripan, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., Grimsdale, Andrew C., Koh, Teck Ming, Li, Hairong, Nonomura, Kazuteru, Mathews, Nripan, Hagfeldt, Anders, Graetzel, Michael, Mhaisalkar, Subodh G., and Grimsdale, Andrew C.

Abstract

Two cyanobiphenyl liquid crystals (LCs), 5CB (4-cyano-4'-pentylbiphenyl) and 8CB (4-cyano-4'-octylbiphenyl), are introduced as additives into Co(II/ III) electrolytes for dye-sensitized solar cells (DSCs). An electrolyte containing a combination of these LCs and 4-tert-butylpyridine (TBP) exhibits higher photovoltage than one with only TBP, resulting in higher power conversion efficiency.

Published
2013
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135. Oxide nanowire networks and their electronic and optoelectronic characteristics

Author

Mathews, Nripan, Varghese, Binni, Sun, Cheng, Thavasi, Velmurugan, Andreasson, Björn Pererik, Sow, Chornghaur H., Ramakrishna, Seeram, Mhaisalkar, Subodh G., Mathews, Nripan, Varghese, Binni, Sun, Cheng, Thavasi, Velmurugan, Andreasson, Björn Pererik, Sow, Chornghaur H., Ramakrishna, Seeram, and Mhaisalkar, Subodh G.

Abstract

Oxide nanowire networks or oxide nanonets leverage some of the exceptional functionalities of one-dimensional nanomaterials along with the fault tolerance and flexibility of interconnected nanowires to creating exciting opportunities in large-area electronics as well as green energy systems. This paper reviews the electronic and optoelectronic properties of these networks and highlights their potential applications in field-effect transistors, optoelectronic devices, and solar cells. Techniques to grow nanowires and their subsequent integration into networks using contact printing and electrospinning are described. Electrical properties of field-effect transistors fabricated from contact printed nanowire networks are discussed, and means of integration of the nanowire networks of heterogenous materials that enable ambipolar device operation are outlined. Photocurrent properties of these nanowires are described, including the dye sensitization of large-bandgap SnO2 nanowires. The final section deals with the advantages of employing nanowire networks in dye-sensitized solar cells and the dependence of solar cell performance on morphology and surface area. © The Royal Society of Chemistry 2010.

Published
2010
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