Bandgap Tunable Ternary Cd x Sb2-y S3-? Nanocrystals for Solar Cell Applications.

ABSTRACT: We report the synthesis and photovoltaic performance of a new nonstoichiometric ternary metal sulfide alloyed semiconductor-Cd x Sb2-y S3-? nanocrystals prepared by the two-stage sequential ionic layer adsorption reaction technique. The synthesized Cd x Sb2-y S3-? nanocrystals retain the orthorhombic structure of the host Sb2S3 with Cd substituting a fraction (x = 0-0.15) of the cationic element Sb. The Cd x Sb2-y S3-? lattice expands relative to the host, Sb2S3, with its lattice constant a increasing linearly with Cd content x. Optical and external quantum efficiency (EQE) spectra revealed that the bandgap E g of Cd x Sb2-y S3-? decreased from 1.99 to 1.69 eV (i.e., 625-737 nm) as x increased from 0 to 0.15. Liquid-junction Cd x Sb2-y S3-? quantum dot-sensitized solar cells were fabricated using the polyiodide electrolyte. The best cell yielded a power conversion efficiency (PCE) of 3.72% with the photovoltaic parameters of J sc = 15.97 mA/cm2, V oc = 0.50 V, and FF = 46.6% under 1 sun. The PCE further increased to 4.86%, a respectable value for a new solar material, under a reduced light intensity of 10% sun. The PCE (4.86%) and J sc (15.97 mA/cm2) are significantly larger than that (PCE = 1.8%, J sc = 8.55 mA/cm2) of the Sb2S3 host. Electrochemical impedance spectroscopy showed that the ZnSe passivation coating increased the electron lifetime by three times. The EQE spectrum of Cd x Sb2-y S3-? has a maximal EQE of 82% at ? = 350 nm and covers the spectral range of 300-750 nm, which is significantly broader than that (300-625 nm) of the Sb2S3 host. The EQE-integrated current density yields a J ph of 11.76 mA/cm2. The tunable bandgap and a respectable PCE near 5% suggest that Cd x Sb2-y S3-? could be a potential candidate for a solar material.

SUBMITTER: Boon-On P 

PROVIDER: S-EPMC6963896 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature