Sulfur deficiency in iron pyrite (FeS2−x) and its consequences for band-structure models

Scientific and Technological Assessment of Iron Pyrite for Use in Solar Devices

“…2018,6,[8][9][10][11][12][13][14][15][16][17][18][19][20] 2018 Wiley-VCH Verlag GmbH &Co. KGaA,W einheim devices could be made,i np rinciple,u sing iron pyrite nanostructures.T oi mprove the photovoltage output, it would be necessary to develop methods for surface treatmenta nd intrinsic defect reduction in iron pyrite.A lso,s hunting pathways could be blocked by making better junctions, which could result in good current rectification to improve device characteristics.…”

“…[7][8][9][10][11] Despitep ossessing such desirable properties,t he success in preparing aw orking solar cell from iron pyrite has been hampered by alack of control on the chemistry of the material and by crystald efects that are believed to be responsible for the low photovoltage output from pyrite solar cells.T he crystal defects manifest as specific material conditions that include Fe-S phase impurities (troilite, greigite,p yrrhotite,e tc. ), stoichiometric deviations, [12][13][14] intrinsic bulk and surface defects, [15][16][17][18] reduced surface energy band gaps, [19] Fermi-level pinning, [20] surface-state-induced band bendinga nd ionized deep donors, [9] and surface inversion layers. [21] These issues were extensively investigated in various studies in the literature,y et they are not fully underIron pyrite (FeS 2 )h olds an enormous potential as al ow cost and non-toxic photoelectrochemicala nd energy-harvesting material owing to its interesting optical, electronic, and chemical properties along with elemental abundance.I nthis Review,l ow cost and scalable processing techniques to synthesize phase-pure pyrite thin films and nanocubes are described, and the application of this material in various energy-harvesting devices such as dye-sensitized solar cells, photodiodes,a nd heterojunctions olar cells is discussed.…”

First-principles studies of the electronic properties of native and substitutional anionic defects in bulk iron pyrite

“…3,4,5,6,7,8 Pyrite photoelectrochemical and solid-state Schottky solar cells have shown large short-circuit current densities (30-42 mA cm -2 ) and quantum efficiencies as high as 90%. 9,10 The main obstacle for the development of pyrite is its low open-circuit photovoltage (V OC ), which is typically only < 200 mV.8 Since 1984, a few dozen studies have explored possible causes of the low V OC , such as bulk nonstoichiometry (mostly S or Fe vacancies), 8,11,12,13 surface states that cause Fermi pinning and thermionic-field emission, and large dark currents, 14,15,16 metallic FeS-like surface layers, 17,18 and small-band gap phase impurities in the pyrite bulk (including marcasite, pyrrhotite, and amorphous iron sulfide phases). 9,19 Nevertheless, there still is no consensus as to the cause of the low V OC or even the nature of the alleged gap states.…”

Density functional theory study of the relative stability of the iron disulfide polymorphs pyrite and marcasite

“…Experimental studies of the lattice parameters of pyrite at different temperatures can be found, however, the majority of temperatures reported are between 294 and 300 K. [42][43][44] If we take these lattice parameters as a function of temperature and extrapolate to zero Kelvin, we can estimate that the lattice parameter of pyrite in the low temperature limit is 5.281 Å. Thermal expansion of lattice parameters would not be completely linear, due to vibrational quantization, and so we can anticipate that the above value is a lower bound to the lattice parameter at absolute zero.…”