Study of alternative back contacts for thin film Cu₂ZnSnSe₄-based solar cells

Investigation of Properties Limiting Efficiency in Cu₂ZnSnSe₄-Based Solar Cells

“…6(a) shows the admittance response of a CZTSe-CdS-ZnO solar cell device with similar processing as compared with our highest efficiency devices, but with an additional TiN layer between the Mo and the absorber. The efficiency of this device is 8.5%, with no antireflective coating deposited and, therefore, very similar efficiency, as compared with the best device presented here [11]. A clear peak can be identified in the derivative of the capacitance response at the different measurement temperatures and the peak shifts to lower frequencies as the temperature is reduced.…”

“…It was shown through variation of the backside contact metal that this behavior was related to a backside contact barrier [11]. The barrier height derived for a Mo backside contact is of the order of 130 meV [10], [5].…”

Refractive index extraction and thickness optimization of Cu2ZnSnSe4thin film solar cells

“…This could be due to the presence of secondary phases as reported in Ref. and a second bandgap as published elsewhere , which could add parasitic light absorption below the main bandgap value.…”

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

“…A thickness as low as 20 nm improved the V OC more than 100 mV and the efficiency from 2.95% to 8.9% [21]. Moreover, an energy barrier at the back contact of 135 meV reported in the literature, was significantly reduced to a value of 15 meV by the introduction of a 100 nm TiN layer, reducing the series resistance, R s , and increasing the efficiency [20]. A 10 nm i-ZnO layer between the Mo and the CZTSe absorber showed a morphology improvement of the back contact interface by reducing voids and minimizing the decomposition reaction, generating less secondary phases at this region identified with Raman spectroscopy.…”

“…It seems clear that to improve CZTSSe devices changes in the processing conditions to maximize V OC must be performed, with the bulk and interfaces of the material as paramount working areas. Whereas chemical etchings have proved to be an important tool to modify the properties of the p-n junction, and therefore improve V OC among other parameters, changing the back contact interface led as well to significant improvements [15][16][17][18][19][20][21]. The present work is devoted to the modification of the properties of the Mo/CZTSe interface by using different Mo configurations (monolayer, bi-layer and tri-layer) and an innovative intermediate ultrathin MoO 2 layer in CZTSe solar cells.…”