Enhanced external quantum efficiency from Cu₂ZnSn(S,Se)₄ solar cells prepared from nanoparticle inks

Abstract

Cu2ZnSn(S,Se)4 (CZTSSe) thin film photovoltaic absorber layers are fabricated by selenizing Cu2ZnSnS4 (CZTS) nanoparticle thin films in a selenium rich atmosphere. The selenium vapor pressure is controlled to optimize the morphology and quality of the CZTSSe thin film. The largest grains are formed at the highest selenium vapor pressure of 226 mbar. Integrating this photovoltaic absorber layer in a conventional thin film solar cell structure yields a champion short circuit current of 37.9 mA/cm2 without an antireflection coating. This stems from an improved external quantum efficiency characteristic in the visible and near-infrared part of the solar spectrum. The physical basis of this improvement is qualitatively attributed to a substantial increase in the minority carrier diffusion length.

Direct evidence of causality between chemical purity and band-edge potential fluctuations in nanoparticle ink-based Cu2ZnSn(S,Se)4 solar cells

“…5d shows the plot of 1/C 2 versus reverse bias voltage where <w > = Aε 0 ε r /C is determined from the measured capacitance value at zero bias and N A is derived from the slope d(1/C 2 )/dV. Very short space charge regions widths of 63 and 61 nm were observed for devices LP and HP respectively, with corresponding apparent doping densities of 2.5 x10 and 3.3 x10 cm −3 , in agreement with those 396 observed by Qu et al (Qu et al, 2018). A high doping density is usually 397 associated with a short depletion width in CZTSSe solar cells as w ∝ N A 398 (Ganchev et al, 2011;Haight et al, 2014).…”

Recovery Mechanisms in Aged Kesterite Solar Cells

“…Solar cell devices were completed by addition of a CdS buffer layer (via chemical bath deposition) as well as window (intrinsic ZnO and conductive In 2 O 3 :SnO 2 (ITO) by magnetron sputtering) and metal contact (Ni and Al by electron beam evaporation) layers. The fabrication process is described in greater detail in the Experimental Section and our previous works. − …”

Ex situ Ge-doping of CZTS nanocrystals and CZTSSe solar absorber films

“…Further details on how the chalcogen exchange was controlled are described elsewhere. 34,35 Solar cell device fabrication. The synthesised CZTSSe solar absorber lms were assembled into solar cell devices in the following substrate conguration: Mo/ (Ge)CZTSSe/CdS/intrinsic zinc oxide (i-ZnO)/indium tin oxide (ITO)/Ni : Al.…”