Solution processing route to Na incorporation in CZTSSe nanoparticle ink solar cells on foil substrate

Abstract

Sodium is a key dopant in thin film photovoltaic cells with reported benefits including promotion of grain growth, passivation of grain boundaries and increased carrier concentration in chalcopyrite and kesterite based solar cells. Research-grade devices fabricated in substrate configuration often rely on diffusion of Na from a soda lime glass substrate into the photovoltaic absorber layer during high temperature processing. However, for samples on flexible substrates such as foils and plastics, this is not available and requires alternative approaches. In this work, we fabricate Earth-abundant Cu 2 ZnSn(S,Se) 4 thin film solar cells from nanoparticle inks on flexible molybdenum substrates and demonstrate a simple, low-cost route to incorporating Na in solution thereby making it compatible with large area, high volume manufacturing. The technique is verified to improve the device efficiency relative to a reference flexible device built on molybdenum foil.

Successes and Challenges Associated with Solution Processing of Kesterite Cu2ZnSnS4 Solar Cells on Titanium Substrates

“…7,8 Other metallic substrates such as molybdenum foil 9,10 and flexible glass 11 have been tested with PCEs reaching up to 6.78 and 3.09%, respectively. In comparison, the performance of devices fabricated with solution-processed absorbers remains much lower than their vacuum counterpart with cell efficiencies of 1.94% reported on aluminum foil-based devices, 12 4.4 13 and 2.42% 14 on molybdenum foil, and 0.49% on polyimide. 15 Although most metal foils appear suitable for roll-to-roll manufacturing of PV devices owing to their flexibility and high electrical conductivity, other parameters need to be considered when optimizing the manufacturing CZTS devices.…”

“…For instance, CZT­(S, Se) light absorbers were successfully grown directly on stainless steel foil to make photovoltaic devices reaching just over 6% efficiency. , Other metallic substrates such as molybdenum foil , and flexible glass have been tested with PCEs reaching up to 6.78 and 3.09%, respectively. In comparison, the performance of devices fabricated with solution-processed absorbers remains much lower than their vacuum counterpart with cell efficiencies of 1.94% reported on aluminum foil-based devices, 4.4 and 2.42% on molybdenum foil, and 0.49% on polyimide …”

“…[7][8] Other metallic substrates such as molybdenum foil [9][10] and flexible glass 11 have been tested with PCEs reaching up to 6.78% and 3.09%, respectively. In comparison, the performance of devices fabricated with solution processed absorbers remains much lower than their vacuum counterpart with cell efficiencies of 1.94% reported on aluminium foil-based devices 12 , 4.4% 13 and 2.42% 14 on molybdenum foil, and 0.49% on Page 4 of 28 polyimide 15 .…”

Modelling Interfaces in Thin-Film Photovoltaic Devices

“…However if the MoS 2 layer is too thick this will be detrimental to device performance, resulting in a reduction in V OC and an increase in the series resistance. (Shin et al, 2012;Xu et al, 2019).…”

A Progress Review on Challenges and Strategies of Flexible Cu2ZnSn(S, Se)4 Solar Cells

“…In recent years, the power conversion efficiency (PCE) of FCSs has developed rapidly and has exceeded 11%, as shown in Figure 1b. In the research, flexible glass, [ 39 ] polyimide, [ 40,41 ] and metal foils [ 42–69 ] are used as flexible substrates. The FCSs reported in recent years are mostly fabricated on Mo foils, stainless steel (SS) foils, and Ti foils.…”