Enhanced intrinsic photovoltaic effect in tungsten disulfide nanotubes

The photovoltaic effect in traditional p–n junctions—where a p-type material (with an excess of holes) abuts an n-type material (with an excess of electrons)—involves the light-induced creation of electron–hole pairs and their subsequent separation, generating a current. This photovoltaic effect is particularly important for environmentally benign energy harvesting, and its efficiency has been increased dramatically, almost reaching the theoretical limit1. Further progress is anticipated by making use of the bulk photovoltaic effect (BPVE)2, which does not require a junction and occurs only in crystals with broken inversion symmetry3. However, the practical implementation of the BPVE is hampered by its low efficiency in existing materials4–10. Semiconductors with reduced dimensionality2 or a smaller bandgap4,5 have been suggested to be more efficient. Transition-metal dichalcogenides (TMDs) are exemplary small-bandgap, two-dimensional semiconductors11,12 in which various effects have been observed by breaking the inversion symmetry inherent in their bulk crystals13–15, but the BPVE has not been investigated. Here we report the discovery of the BPVE in devices based on tungsten disulfide, a member of the TMD family. We find that systematically reducing the crystal symmetry beyond mere broken inversion symmetry—moving from a two-dimensional monolayer to a nanotube with polar properties—greatly enhances the BPVE. The photocurrent density thus generated is orders of magnitude larger than that of other BPVE materials. Our findings highlight not only the potential of TMD-based nanomaterials, but also more generally the importance of crystal symmetry reduction in enhancing the efficiency of converting solar to electric power. A bulk photovoltaic effect is observed in devices based on tungsten disulfide, and is enhanced if the devices take the form of polar nanotubes, showing the importance of reducing crystal symmetry to a polar structure in achieving higher efficiencies.

[1]  Wang Yao,et al.  Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. , 2011, Physical review letters.

[2]  R. Tenne,et al.  Polyhedral and cylindrical structures of tungsten disulphide , 1992, Nature.

[3]  M. Wahiduzzaman,et al.  Electromechanics in MoS2 and WS2: nanotubes vs. monolayers , 2013, Scientific Reports.

[4]  P Shafer,et al.  Above-bandgap voltages from ferroelectric photovoltaic devices. , 2010, Nature nanotechnology.

[5]  T. Morimoto,et al.  Topological aspects of nonlinear excitonic processes in noncentrosymmetric crystals , 2015, 1512.00549.

[6]  J. Wilson,et al.  The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties , 1969 .

[7]  Reshef Tenne,et al.  Scaling Up of the WS2 Nanotubes Synthesis , 2010 .

[8]  A. Calzolari,et al.  Spontaneous polarization and piezoelectricity in boron nitride nanotubes , 2003, cond-mat/0305329.

[9]  R. Tenne,et al.  Optoelectronic response of a WS2 tubular p-n junction , 2018 .

[10]  B. Sturman,et al.  The Photovoltaic and Photorefractive Effects in Noncentrosymmetric Materials , 2021 .

[11]  S. Szymczak,et al.  Vy-PER: eliminating false positive detection of virus integration events in next generation sequencing data , 2015, Scientific Reports.

[12]  Wang Yao,et al.  Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides , 2012, Scientific Reports.

[13]  Symmetry regimes for circular photocurrents in monolayer MoSe2 , 2018, Nature Communications.

[14]  G. Burkard,et al.  Tight-Binding Approach to Strain and Curvature in Monolayer Transition-Metal Dichalcogenides , 2015, 1511.06254.

[15]  R. Tenne,et al.  Superconductivity in a chiral nanotube , 2017, Nature Communications.

[16]  D. Oron,et al.  Strong light-matter interaction in tungsten disulfide nanotubes. , 2018, Physical chemistry chemical physics : PCCP.

[17]  Y. J. Zhang,et al.  Electrically Switchable Chiral Light-Emitting Transistor , 2014, Science.

[18]  J. Tauc,et al.  Generation of an emf in Semiconductors with Nonequilibrium Current Carrier Concentrations , 1957 .

[19]  Z. Trousil.  Bulk photo-voltaic phenomenon , 1956 .

[20]  J. Warner,et al.  Layer-dependent modulation of tungsten disulfide photoluminescence by lateral electric fields. , 2015, ACS nano.

[21]  Xitao Liu,et al.  A Photoferroelectric Perovskite-Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects. , 2016, Angewandte Chemie.

[22]  Reshef Tenne,et al.  INSIGHT INTO THE GROWTH MECHANISM OF WS2 NANOTUBES IN THE SCALED-UP FLUIDIZED-BED REACTOR , 2009 .

[23]  Hongtao Yuan,et al.  Generation and electric control of spin-valley-coupled circular photogalvanic current in WSe2. , 2014, Nature Nanotechnology.

[24]  Marco Bernardi,et al.  Extraordinary sunlight absorption and one nanometer thick photovoltaics using two-dimensional monolayer materials. , 2013, Nano letters.

[25]  T. Kurumaji,et al.  Shift current photovoltaic effect in a ferroelectric charge-transfer complex , 2017, Nature Communications.

[26]  R. Maeda,et al.  Photovoltaic effect of lead lanthanum zirconate titanate in a layered film structure design , 2004 .

[27]  M. Shen,et al.  High-efficiency ferroelectric-film solar cells with an n-type Cu₂O cathode buffer layer. , 2012, Nano letters.

[28]  O. Alon.  Symmetry properties of single-walled boron nitride nanotubes , 2001 .

[29]  K. O'Donnell,et al.  Temperature dependence of semiconductor band gaps , 1991 .

[30]  Helmuth Berger,et al.  Quantitative determination of the band gap of WS2 with ambipolar ionic liquid-gated transistors. , 2012, Nano letters.

[31]  William Shockley,et al.  The theory of p-n junctions in semiconductors and p-n junction transistors , 1949, Bell Syst. Tech. J..

[32]  L. Qin,et al.  Accurate measurement of the chirality of WS2 nanotubes. , 2017, Nanoscale.

[33]  P. S. Brody.  High voltage photovoltaic effect in barium titanate and lead titanate-lead zirconate ceramics , 1975 .

[34]  J. Miyazaki,et al.  Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating , 2015, Scientific Reports.

[35]  M. Alexe,et al.  Tip-enhanced photovoltaic effects in bismuth ferrite , 2011 .

[36]  T. Morimoto,et al.  Topological nature of nonlinear optical effects in solids , 2015, Science Advances.

[37]  Silvia Licoccia,et al.  Photovoltaic properties of Bi2FeCrO6 epitaxial thin films , 2011 .

[38]  T. Morimoto,et al.  Quantitative relationship between polarization differences and the zone-averaged shift photocurrent , 2016, 1701.00172.

[39]  M. Alexe,et al.  Flexo-photovoltaic effect , 2018, Science.

[40]  R. Tenne,et al.  Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures , 2008, Proceedings of the National Academy of Sciences.

[41]  A. L. Tolstikhina,et al.  Giant bulk photovoltaic effect in thin ferroelectricBaTiO3films , 2014 .

[42]  T. Morimoto,et al.  Large Bulk Photovoltaic Effect and Spontaneous Polarization of Single-Layer Monochalcogenides. , 2016, Physical review letters.

[43]  H. Frank.  Lichtelelektrische Messung des inneren elektrischen Feldes in inhomogenen Halbleitern , 1956 .

[44]  Jinsong Huang,et al.  Arising applications of ferroelectric materials in photovoltaic devices , 2014 .

[45]  Joel E Moore,et al.  Design principles for shift current photovoltaics , 2015, Nature Communications.

[46]  Zhiyong Zhang,et al.  High-performance photodetectors for visible and near-infrared lights based on individual WS2 nanotubes , 2012 .

[47]  Zhong Lin Wang,et al.  Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics , 2014, Nature.

[48]  Liyan Wu,et al.  Perovskite oxides for visible-light-absorbing ferroelectric and photovoltaic materials , 2013, Nature.

[49]  O. H. Hughes,et al.  Semiconductor Physics , 1967, Nature.

[50]  Qingfeng Dong,et al.  Giant switchable photovoltaic effect in organometal trihalide perovskite devices. , 2015, Nature materials.

[51]  F. Xia,et al.  Photoconductivity of biased graphene , 2012, Nature Photonics.

[52]  Photogalvanic effects in heteropolar nanotubes , 2000, Physical review letters.