Improvement of J_sc in a Cu₂ZnSnS₄ Solar Cell by Using a Thin Carbon Intermediate Layer at the Cu₂ZnSnS₄/Mo Interface

Abstract

Back contact modification plays an important role in improving energy conversion efficiency of Cu2ZnSnS4 (CZTS) thin film solar cells. In this paper, an ultrathin carbon layer is introduced on molybdenum (Mo)-coated soda lime glass (SLG) prior to the deposition of CZTS precursor to improve the back contact and therefore enhance CZTS solar cell efficiency. By introducing this layer, the short circuit current (Jsc) and device conversion efficiency increase for both nonvacuum (sol-gel) and vacuum (sputtering) methods. Specifically, for the sol-gel based process, Jsc increases from 13.60 to 16.96 mA/cm(2) and efficiency from 4.47% to 5.52%, while for the sputtering based process, Jsc increases from 17.50 to 20.50 mA/cm(2) and efficiency from 4.10% to 5.20%. Furthermore, introduction of this layer does not lead to any deterioration of either open circuit voltage (Voc) or fill factor (FF).

Impact of molybdenum out diffusion and interface quality on the performance of sputter grown CZTS based solar cells

“…They introduced titanium nitride (TiN)- as passivated back contact to suppress diffusion of sulphur atoms and reactions between CZTS and Mo, however, overall series resistance increases that results in reduction of fill factor. There are several approaches to improve the back contact between Mo and CZTS 11, 30, 33 . To reduce the series resistance of the CZTS/Mo device, ultrathin carbon layer was introduced on Mo-coated soda-lime glass (SLG) prior to the deposition of CZTS layer 11 .…”

“…Since sulphur is present in the quaternary Cu 2 ZnSnS 4 target; interfacial layer formation mechanism is different than the CZTS layer grown by sputter with multilayer layer metal films followed by sulphur annealing. CZTS-Mo interface plays a critical role to decide the efficiency of the solar cells 11, 12 and it is difficult to avoid the formation of MoS x layer. Therefore, in this work, the impact of Mo out-diffusion into CZTS films and formation of MoS x layer is addressed and solar cell performance is evaluated for the sputter-grown CZTS film.…”

A low-cost, sulfurization free approach to control optical and electronic properties of Cu2ZnSnS4 via precursor variation

“…The spectra has been deconvoluted to gain a better understanding of the different phases present in the material and changes in their relative intensity with changes in the precursor ratio. The peaks at ~334 cm -1 and ~287 cm -1 are the primary and secondary characteristic peaks for kesterite CZTS phase respectively [32][33][34]. The peaks at ~358 cm -1 and ~657 cm -1 can be attributed to ZnS [33,35] while the peak at ~471 cm -1 belongs to Cu2-xS [33], both of which are unwanted secondary phases.…”

Cu2ZnSnS4 Thin Films Generated from a Single Solution Based Precursor: The Effect of Na and Sb Doping

“…[6][7][8] The highest performances obtained for CZTS and CZTSSe via direct liquid processing (without anti-reflecting coating) are 5.5 and 11.8%, respectively. 7,9 Despite important efforts in developing preparation methods for high quality CZTSSe films, devices consistently show lower efficiencies than state-of-the-art CIGS systems, in particular low open circuit voltages (V OC ).…”

“…This performance recorded in 0.5 cm 2 cells without ARC is among the highest reported for CZTS films. 3,8,9,13,14,22 …”