17.6%-Efficient radial junction solar cells using silicon nano/micro hybrid structures.

We developed a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with an area of 1 cm(2) exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA cm(-2) because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.

[1]  Gang Chen,et al.  Analysis of optical absorption in silicon nanowire arrays for photovoltaic applications. , 2007, Nano letters.

[2]  Supratik Guha,et al.  Characteristics of vapor–liquid–solid grown silicon nanowire solar cells , 2009 .

[3]  Nathan S Lewis,et al.  Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications. , 2010, Nature materials.

[4]  Nathan S. Lewis,et al.  Silicon Microwire Arrays for Solar Energy-Conversion Applications , 2014 .

[5]  Kui‐Qing Peng,et al.  Preparation of Large-Area Uniform Silicon Nanowires Arrays through Metal-Assisted Chemical Etching , 2008 .

[6]  Harold Dekkers,et al.  Very low surface recombination velocities on p-type silicon wafers passivated with a dielectric with fixed negative charge , 2006 .

[7]  Kwang-Tae Park,et al.  Incorporation of a self-aligned selective emitter to realize highly efficient (12.8%) Si nanowire solar cells. , 2014, Nanoscale.

[8]  Peidong Yang,et al.  Light trapping in silicon nanowire solar cells. , 2010, Nano letters.

[9]  Majid Gharghi,et al.  On the design and applicability of nanowire solar cells using low-grade semiconductors , 2012 .

[10]  Aric Kumaran Menon,et al.  Wettability and thermal stability of fluorocarbon films deposited by deep reactive ion etching , 2005 .

[11]  Hao-Chih Yuan,et al.  An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures. , 2012, Nature nanotechnology.

[12]  Chito Kendrick,et al.  Enhanced conversion efficiencies for pillar array solar cells fabricated from crystalline silicon with short minority carrier diffusion lengths , 2010 .

[13]  Otto L Muskens,et al.  Design of light scattering in nanowire materials for photovoltaic applications. , 2008, Nano letters.

[14]  Kui‐Qing Peng,et al.  Silicon Nanowires for Photovoltaic Solar Energy Conversion , 2011, Advanced materials.

[15]  Zongfu Yu,et al.  Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays. , 2009, Nano letters.

[16]  Nathan S. Lewis,et al.  Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells , 2005 .

[17]  Inchan Hwang,et al.  Microgrid Electrode for Si Microwire Solar Cells with a Fill Factor of Over 80% , 2015 .

[18]  Haider Butt,et al.  Nanowire-based multifunctional antireflection coatings for solar cells. , 2014, Nanoscale.

[19]  N. Lewis.  Toward Cost-Effective Solar Energy Use , 2007, Science.

[20]  Jr-Hau He,et al.  Light scattering by nanostructured anti-reflection coatings , 2011 .

[21]  Anja Boisen,et al.  Dry release of all-polymer structures , 2005 .

[22]  Inchan Hwang,et al.  Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications , 2015, Scientific Reports.

[23]  Zhong Lin Wang,et al.  Wafer-scale high-throughput ordered arrays of Si and coaxial Si/Si(1-x)Ge(x) wires: fabrication, characterization, and photovoltaic application. , 2011, ACS nano.

[24]  Jin He,et al.  Progress and Design Concerns of Nanostructured Solar Energy Harvesting Devices. , 2016, Small.

[25]  Zhongyi Guo,et al.  A waferscale Si wire solar cell using radial and bulk p–n junctions , 2010, Nanotechnology.

[26]  Gong-Ru Lin,et al.  Subwavelength Si nanowire arrays for self-cleaning antireflection coatings , 2010 .

[27]  Pere Roca i Cabarrocas,et al.  Bismuth-catalyzed and doped silicon nanowires for one-pump-down fabrication of radial junction solar cells. , 2012, Nano letters.

[28]  Jurriaan Huskens,et al.  Effects of Pillar Height and Junction Depth on the Performance of Radially Doped Silicon Pillar Arrays for Solar Energy Applications , 2016 .

[29]  Zhongyi Guo,et al.  Optical properties of Si microwires combined with nanoneedles for flexible thin film photovoltaics. , 2011, Optics express.

[30]  Martin A. Green.  Two new efficient crystalline silicon light‐trapping textures , 1999 .

[31]  Nathan S. Lewis,et al.  Si microwire-array solar cells , 2010 .

[32]  Hyunsung Park,et al.  Si microwire solar cells: improved efficiency with a conformal SiO2 layer. , 2013, ACS nano.

[33]  Paul Stradins,et al.  Efficient black silicon solar cell with a density-graded nanoporous surface: Optical properties, performance limitations, and design rules , 2009 .

[34]  J. John,et al.  Spatially-separated atomic layer deposition of Al2O3, a new option for high-throughput si solar cell passivation , 2011, 2011 37th IEEE Photovoltaic Specialists Conference.

[35]  Claude Lévy-Clément,et al.  Metal-assisted chemical etching of silicon in HF–H2O2 , 2008 .

[36]  M. Yamaguchi,et al.  Light trapping effect of submicron surface textures in crystalline Si solar cells , 2007 .