Final Report: Sintered CZTS Nanoparticle Solar Cells on Metal Foil; July 26, 2011 - July 25, 2012

Abstract

Printed on paper containing at least 50% wastepaper, including 10% post consumer waste.However the lengthy thermal process used in that tool is not viewed as a commercially scalable process, primarily due to its extended process time. Therefore the effort to use an RTP process was launched at the beginning of the project in order to develop a faster absorber formation process for eventual transfer to Solexant's pilot process line. Characterization ToolsSolexant has an array of analytical tools in-house that were used extensively throughout this project effort. These tools include scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron beam induced current (EBIC), electron dispersive spectroscopy (EDS), white-light interferometry, Infrared Thermography, optical absorption spectroscopy, xray fluorescence (XRF), capacitance-voltage (C-V), current-voltage (I-V) and light-biased quantum efficiency (QE). We had collaborative efforts with NREL's Measurement and Characterization group for lock-in Infrared Thermography, SEM, focused ion beam (FIB)-SEM and EDS, STEM, EBIC, cathodoluminescence (CL) and Raman.

The importance of back contact modification in Cu2ZnSnSe4 solar cells: The role of a thin MoO2 layer

“…Therefore, we decided to invert the typical stack order of bi-layers configuration in terms of pressure that is commonly reported in the literature: bottom/high pressure and top/low pressure, in order to deal with this problem. The main reason to do so, is that an increase in the sputtering pressure can lead to a higher incorporation of O 2 from the background sputtering environment reducing the formation of MoSe 2 [31]. This can be due to a more porous structure with more intergranular space where impurities can be adsorbed and/or diffuse [36,38].…”

“…In the case of CZTS, an increase in O content in the Mo back contact, via annealing in N 2 atmosphere at 550ºC for 10 min, coupled with an increase in Na content, led to a reduction of the MoS 2 layer after the thermal annealing, reducing considerably the R S [30]. A similar effect, reducing MoSe 2 thickness, has been reported to be beneficial for CZTSSe solar cells, where 1% of O 2 was incorporated to the Mo during the sputtering process [31].Thus, it can be inferred that the study of Mo oxidation processes and/or its oxides, MoO 2 and MoO 3 are highly relevant for the thin film solar cell community.…”

A low-cost, ligand exchange-free strategy to synthesize large-grained Cu2ZnSnS4 thin-films without a fine-grain underlayer from nanocrystals

“…One approach employs hydrazine as a reactive solvent to dissolve the precursors of CZTS. 8 Promising alternative hydrazine-free approaches include (1) the hydrazine-free sol-gel approach 9-13 and (2) the nanocrystal approach, [14][15][16][17][18][19] both of which have demonstrated solar cells with efficiencies exceeding 8%. Solar cells fabricated using these films have demonstrated record high efficiencies.…”

Characterization of Cu2ZnSnSe4 (CZTSe) nanoparticles synthesized via solvothermal method for solar cell applications

“…However, hydrazine, used as solvent in such process, is highly toxic and requires careful handling. Solar cells with conversion efficiency of 10.2 % have been fabricated using CZTSSe absorbers that have been grown with CZTS nanoparticles [19]. Current research is mainly focused on the synthesis of CZTSe particles using a non-vacuum based solvothermal process with less toxic solvents for solar cell application.…”

“…The size and composition of various binary, ternary and quaternary sulfo/selenide nanoparticles has been optimized for preparing precursor inks. CZTSSe solar cells are mostly fabricated with CZTS nanocrystals [19][20][21] rather than CZTSe nanocrystals, since CZTS nanocrystals with a spherical morphology can be obtained easily compared to CZTSe nanocrystals. Recently, many groups have reported synthesis of CZTSe nanoparticles via solvothermal and hot injection methods [22][23][24][25][26][27][28][29][30].…”