Solution-Processed Zinc Phosphide (α-Zn₃P₂) Colloidal Semiconducting Nanocrystals for Thin Film Photovoltaic Applications

Abstract

Zinc phosphide (Zn3P2) is a promising earth-abundant material for thin film photovoltaic applications, due to strong optical absorption and near ideal band gap. In this work, crystalline zinc phosphide nanoparticles are synthesized using dimethylzinc and tri-n-octylphosphine as precursors. Transmission electron microscopy and X-ray diffraction data show that these nanoparticles have an average diameter of ∼8 nm and adopt the crystalline structure of tetragonal α-Zn3P2. The optical band gap is found to increase by 0.5 eV relative to bulk Zn3P2, while there is an asymmetric shift in the conduction and valence band levels. Utilizing layer-by-layer deposition of Zn3P2 nanoparticle films, heterojunction devices consisting of ITO/ZnO/Zn3P2/MoO3/Ag are fabricated and tested for photovoltaic performance. The devices are found to exhibit excellent rectification behavior (rectification ratio of 600) and strong photosensitivity (on/off ratio of ∼10(2)). X-ray photoelectron spectroscopy and ultraviolet photoemission spectroscopy analyses reveal the presence of a thin 1.5 nm phosphorus shell passivating the surface of the Zn3P2 nanoparticles. This shell is believed to form during the nanoparticle synthesis.

Earth‐Rich Transition Metal Phosphide for Energy Conversion and Storage

“…Two solvothermal synthetic strategies for crystalline Zn 3 P 2 nanospheres with different sizes are described in Figure c. Apparently, the advent of P(SiMe 3 ) 3 as the assisted phosphorus source realized the bigger Zn 3 P 2 nanospheres with diameter of ≈15 nm via a lower temperatures of 150 °C and shorter reaction time of 1 h. It was reasonable that phosphido‐bridged dimeric Zn(II) intermediates caused a compact linkage of metal‐phosphorus, rather than the metallic zinc species . Very recently, organism phytic acid (PA) as a principle phosphorus material was adopted to form TMPs.…”

Size‐Tunable Synthesis of Colloidal Silver Sulfide Nanocrystals for Solution‐Processed Photovoltaic Applications

“…The most widely investigated quantum dots based on cadmium and lead chalcogenides (CdX and PbX where X=S, Se, Te) exhibit excellent performance in the solution processed photovoltaic devices by harvesting photon from visible to IR region . However, due to toxic nature of Cd and Pb extensive research is being carried out to synthesize the material which contains lesser toxic elements and have narrow band gap such as Bi 2 S 3 ,, FeS 2 , and Zn 2 P 3 …”

Ternary synthesis of colloidal Zn3P2quantum dots

“…12,13 To date, there have been seven accounts of colloidal syntheses of Zn 3 P 2 . [14][15][16][17][18][19][20] The earliest study showed formation of zinc phosphide clusters with a distinct lowest energy excitonic transition (LEET) at 300 nm, indicative of relatively uniform crystalline particles, with an approximated 1 nm diameter. However, larger particles could not be obtained by this method.…”