Coaxial Group III−Nitride Nanowire Photovoltaics

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• 作者：Yajie Dong ; Bozhi Tian ; Thomas J. Kempa ; Charles M. Lieber
• 刊名：Nano Letters
• 出版年：2009
• 出版时间：May 13, 2009
• 年：2009
• 卷：9
• 期：5
• 页码：2183-2187
• 全文大小：216K
• 年卷期：v.9,no.5(May 13, 2009)
• ISSN：1530-6992

文摘

Coaxial core/shell nanowires represent an important class of nanoscale building blocks with substantial potential for exploring new concepts and materials for solar energy conversion. Here, we report the first experimental realization of coaxial group III−nitride nanowire photovoltaic (PV) devices, n-GaN/i-In_xGa_1−xN/p-GaN, where variation of indium mole fraction is used to control the active layer band gap and hence light absorption. Current−voltage data reveal clear diode characteristics with ideality factors from 3.9 to 5.6. Electroluminescence measurements demonstrate tunable emission from 556 to 371 nm and thus confirm band gap variations in the In_xGa_1−xN active layer from 2.25 to 3.34 eV as In composition is varied. Simulated one-sun AM 1.5G illumination yielded open-circuit voltages (V_oc) from 1.0 to 2.0 V and short-circuit current densities (J_sc) from 0.39 to 0.059 mA/cm² as In composition is decreased from 0.27 to 0 and a maximum efficiency of 0.19%. The n-GaN/i-In_xGa_1−xN/p-GaN nanowire devices are highly robust and exhibit enhanced efficiencies for concentrated solar light illuminations as well as single nanowire J_sc values as high as 390 mA/cm² under intense short-wavelength illumination. The ability to rationally tune the structure and composition of these core/shell III−nitride nanowires will make them a powerful platform for exploring nanoenabled PVs in the future.