Jianbo Gao | National Renewable Energy Laboratory (original) (raw)
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Papers by Jianbo Gao
Nano letters, Jan 1, 2011
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The Journal of Organic …, Jan 1, 2009
The synthesis of pentacene-based dendrimers has been achieved via esterification of 1,3,5-benzene... more The synthesis of pentacene-based dendrimers has been achieved via esterification of 1,3,5-benzenetricarboxylic acid and unsymmetrical pentacene 4 possessing a hydroxy group. Dendrimers 1 (C 183 H 204 O 9 Si 9 , 2800 g mol -1 ) and 2 (C 540 H 570 O 30 Si 24 , 8214 g mol -1 ) are characterized by 1 H and 13 C NMR, IR, UV-vis, and fluorescence spectroscopy, as well as mass spectrometry. These branched oligomeric materials are benchtop stable and soluble in common organic solvents, allowing for solution cast formation of thin films. Photocurrent and photocurrent yield measurements of these films reveal improved efficiency in photogenerated conduction for dendrimers in comparison to linearly connected pentacene-based polymers.
Nano letters, Jan 1, 2011
The current-voltage (J-V) characteristics of ZnO/PbS quantum dot (QD) solar cells show a QD sized... more The current-voltage (J-V) characteristics of ZnO/PbS quantum dot (QD) solar cells show a QD sizedependent behavior resulting from a Schottky junction that forms at the back metal electrode opposing the desirable diode formed between the ZnO and PbS QD layers. We study a QD size-dependent roll-over effect that refers to the saturation of photocurrent in forward bias and crossover effect which occurs when the light and dark J-V curves intersect. We model the J-V characteristics with a main diode formed between the n-type ZnO nanocrystal (NC) layer and p-type PbS QD layer in series with a leaky Schottky-diode formed between PbS QD layer and metal contact. We show how the characteristics of the two diodes depend on QD size, metal work function, and PbS QD layer thickness, and we discuss how the presence of the back diode complicates finding an optimal layer thickness. Finally, we present Kelvin probe measurements to determine the Fermi level of the QD layers and discuss band alignment, Fermi-level pinning, and the V oc within these devices.
Organic letters, Jan 1, 2008
Conjugated pentacene dimers 1-3 were synthesized in two steps from readily available precursors. ... more Conjugated pentacene dimers 1-3 were synthesized in two steps from readily available precursors. Noteworthy is the initial step, which assembles five independent fragments to form the carbon-rich molecular framework. Solution-cast films of these materials are air stable. Photocurrent measurements for solution-deposited thin films show that dimer 3 exhibits photoconductive gain >10.
Nano letters, Jan 1, 2011
The user has requested enhancement of the downloaded file.
The Journal of Organic …, Jan 1, 2009
The synthesis of pentacene-based dendrimers has been achieved via esterification of 1,3,5-benzene... more The synthesis of pentacene-based dendrimers has been achieved via esterification of 1,3,5-benzenetricarboxylic acid and unsymmetrical pentacene 4 possessing a hydroxy group. Dendrimers 1 (C 183 H 204 O 9 Si 9 , 2800 g mol -1 ) and 2 (C 540 H 570 O 30 Si 24 , 8214 g mol -1 ) are characterized by 1 H and 13 C NMR, IR, UV-vis, and fluorescence spectroscopy, as well as mass spectrometry. These branched oligomeric materials are benchtop stable and soluble in common organic solvents, allowing for solution cast formation of thin films. Photocurrent and photocurrent yield measurements of these films reveal improved efficiency in photogenerated conduction for dendrimers in comparison to linearly connected pentacene-based polymers.
Nano letters, Jan 1, 2011
The current-voltage (J-V) characteristics of ZnO/PbS quantum dot (QD) solar cells show a QD sized... more The current-voltage (J-V) characteristics of ZnO/PbS quantum dot (QD) solar cells show a QD sizedependent behavior resulting from a Schottky junction that forms at the back metal electrode opposing the desirable diode formed between the ZnO and PbS QD layers. We study a QD size-dependent roll-over effect that refers to the saturation of photocurrent in forward bias and crossover effect which occurs when the light and dark J-V curves intersect. We model the J-V characteristics with a main diode formed between the n-type ZnO nanocrystal (NC) layer and p-type PbS QD layer in series with a leaky Schottky-diode formed between PbS QD layer and metal contact. We show how the characteristics of the two diodes depend on QD size, metal work function, and PbS QD layer thickness, and we discuss how the presence of the back diode complicates finding an optimal layer thickness. Finally, we present Kelvin probe measurements to determine the Fermi level of the QD layers and discuss band alignment, Fermi-level pinning, and the V oc within these devices.
Organic letters, Jan 1, 2008
Conjugated pentacene dimers 1-3 were synthesized in two steps from readily available precursors. ... more Conjugated pentacene dimers 1-3 were synthesized in two steps from readily available precursors. Noteworthy is the initial step, which assembles five independent fragments to form the carbon-rich molecular framework. Solution-cast films of these materials are air stable. Photocurrent measurements for solution-deposited thin films show that dimer 3 exhibits photoconductive gain >10.