Compositional Inhomogeneity of Multinary Semiconductor Nanoparticles: A Case Study of Cu₂ZnSnS₄

Abstract

Probe-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the inter-and intraparticle compositional inhomogeneity of multinary Cu 2 ZnSnS 4 (CZTS) nanoparticles. CZTS nanoparticles were prepared following three distinct synthesis protocols described in the literature. Strong fluctuations in composition were observed for Cu and Zn in individual nanoparticles, independent of the synthesis method. Certain particles have regions that have compositions close to that of Cu 2 SnS 3 , as well as, in the extreme case, the presence of nearly pure ZnS species. This is an observation that has not been reported in prior studies of these systems and underscores the need to both more carefully study the polydispersity of multinary semiconductor nanoparticles (MSNs) and to improve synthetic protocols and characterization of MSNs. Notablydespite the observation of compositional fluctuations in individual nanoparticlesreactive sintering in Se vapor was shown to reduce the nanoscale compositional fluctuations in the resulting sintered grains, facilitating the use of these heterogeneous particles in optoelectronic devices.

Influence of Processing Conditions on the Performance of Cu2ZnSnS4 Nanocrystal Solar Cells

“…Yang et al. have recently reported a large fluctuation in composition in individual CZTS NCs, independent of the synthesis method . It is reasonable that in a complex quaternary system the compositional inhomogeneity would form in the very small crystals.…”

Scalable Heating-Up Synthesis of Monodisperse Cu2ZnSnS4 Nanocrystals

“…On ensemble level, oftentimes shape and size-uniformity of multinary nanocrystals are indicative of their intrinsic chemical homogeneity. [16][17][18][19] In other words, monodisperse nanocrystals are more likely to be also chemically identical.…”

Non-toxic precursor solution route for fabrication of CZTS solar cell based on all layers solution processed

“…For CZTS absorber layer, compared to the colloidal nanoparticles deposition, precursor solution deposition has the advantage of compositional uniformity due to atomic level mixing of elements. Further, the precursor solution method circumvents nanoparticles synthesis step and provides controllable film morphology [15][16][17][18][19]. In order to prepare non-toixc CZTS absorber layer deposition, numerous green chemistry or non-toxic approaches have been developed to synthesize semiconductors nanoparticles or precursor film [6,[19][20][21].…”