Air Stable, Photosensitive, Phase Pure Iron Pyrite Nanocrystal Thin Films for Photovoltaic Application

Abstract

Iron pyrite (FeS(2)) is a naturally abundant and nontoxic photovoltaic material that can potentially make devices as efficient as silicon-based ones; however existing iron pyrite photovoltaic devices contain thermodynamically unstable FeS(2) film surfaces that lead to low open circuit voltages. We report the rational synthesis of phase pure, highly crystalline cubic FeS(2) nanocrystals (NCs) using a trioctylphosphine oxide (TOPO) assisted hot-injection method. The synthesized pyrite NC films have excellent air stability over one year. In contrast, obvious surface decomposition was observed on the surface of FeS(2) NCs synthesized without TOPO. A high carrier mobility of 80 cm(2)/(V s) and a strong photoconductivity were observed for the first time for pyrite films at room temperature. Our results indicate that TOPO passivates both iron and sulfur atoms on FeS(2) NC surfaces, efficiently inhibiting surface decomposition.

Uranium sorption characteristics onto synthesized pyrite

“…The XRD peaks of pyrite can be indexed in peak position as a pure pyrite of FeS 2 , which is consistent with that of FeS 2 crystal (JCPDs No. 42-130) [20]. The corresponding lattice constants of synthesized FeS 2 were determined as a = b = c = 5.42 Å , and b = 90°, indicating that the prepared pyrite crystal structure is simple cubic.…”

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.…”

“…[22] Attempts to study these fundamental factorstou nderstand the problem of low output photovoltage,a nd above-mentioned issues,h ave led to the utilization of severals ynthesis and processing schemes,w hich have resulted in numerous types of thin films and nanostructures in iron pyrite. [11,[23][24][25][26][27][28][29][30] Early attempts by Tr ibutsch and wo-workerst op repare iron pyrite-sensitized TiO 2 solar cells showedh igh externalq uantum efficiency( up to % 90 %), but the overall efficiency remained low because of limited photovoltage. [31,32] Recent studies on similar device structures also validate these findings.…”

Thin Film Solar Cells Using Earth-Abundant Materials

“…Wadia and his group show single phase growth of FeS 2 nanoparticles. On the other hand, colloidal FeS 2 nano-crystal ink by using a hot-injection method has been synthesized by many groups [112][113][114][115][116]. These processes are encouraging in that these are low temperature processes and variation in particle sizes allows the manipulation of band gap, which will help to absorb a broader spectrum of sunlight.…”