Abstract
The effects of unintentionally formed n-type transition metal dichalcogenide namely molybdenum telluride (MoTe2) in between Cadmium Telluride (CdTe) absorber layer and Mo back contact is studied from numerical modeling and analysis. The main objective is to analyze the possible effects of n-MoTe2 formation in CdTe thin film solar cell. Energy band line-up of Mo/MoTe2/CdTe interface is investigated in order to explain the interface properties with different parameters. Carrier concentration, bandgap energy, electron affinity and thickness of n-MoTe2 have been varied in the numerical simulation to observe its effects on overall photovoltaic performance. The increase in the carrier concentration and bandgap energy of n-MoTe2 deteriorates the overall performance. This could be attributed to the high value of built-in-potential (V-bi) along with band offset value at n-MoTe2/p-CdTe interface, which causes the electrons to be drifted back towards the back contact and results in recombination. Advantageous effects are observed as the electron affinity of n-MoTe2 is increased. This can be explained by the lower value of band offset (Delta E-C and Delta E-V) at n-MoTe2/p-CdTe interface that interrupts the flow of carriers in overall circuit in a moderate way. Numerical results reveal that n-MoTe2 layer thinner than 50 nm affects adversely, possibly due to the shunting.