Effect of p-type transition metal dichalcogenide molybdenum ditelluride (p-MoTe2) layer formation in Cadmium Telluride solar cells from numerical analysis
In this paper, we have investigated the effects of transition metal dichalcogenide namely Molybdenum ditelluride (MoTe2) layer formation in between Cadmium Telluride (CdTe) absorber layer and Mo back contact from numerical modeling. The main purpose was to investigate the possible effects of p-type MoTe2 in CdTe thin film solar cell. Energy band line-up in the vicinity of Mo/MoTe2/CdTe interface is investigated to explain the interface properties in terms of various parameters. It was found that p-type MoTe2 has some effects to the performance of CdTe thin film solar cells. Thickness, bandgap energy and carrier concentration of p-MoTe2 all have been varied in the numerical simulation to observe its effects on the cell performance. It was found that when thickness of MoTe2 is less than 20 nm, the cell efficiency decreases, which may be due to the shunting caused by the thinner p-MoTe2. Furthermore, the increase in MoTe2 bandgap results in unfavorable effect to the performance of the cell mainly due to the possibility of electrons to drift towards the back contact and recombination. The increase of the carrier concentration improves the cell performance. This could be attributed to the less recombination of electrons as well as less built in potential (Vbi) at MoTe2/CdTe junction.
High performance and stable molybdenum telluride PV cells with Indium Telluride BSF
Molybdenum telluride (MoTe<sub>2</sub>) is a very promising candidate as PV cell for better cell stability and performance. In this research work, AMPS (Analysis of Microelectronic and Photonic Structures) simulator was used to examine the performance parameters (Jsc, Voc, FF and conversion efficiency) of ultra-thin MoTe<sub>2</sub> PV cell through numerical analysis. During the study, it was found that absorber layer thickness of MoTe<sub>2</sub> PV cell is adequate to achieve cell efficiency at satisfactory level. In addition, the hidden potentiality of MoTe<sub>2</sub> PV cell was examined by inserting Indium Telluride (ImTe<sub>3</sub>) back surface field (BSF) between absorber layer and back contact metal. The conversion efficiency of 17.06% (FF = 0.730, V<sub>oc</sub> = 0.98 V and J<sub>sc</sub> = 23.74 mA/cm<sup>2</sup>) has been achieved for 1 μm absorber layer of MoTe<sub>2</sub> PV cell without BSF, whereas higher conversion efficiency is 25.29% (FF = 0.847, V<sub>oc</sub> = 1.08 V and Jsc = 27.60 mA/cm<sup>2</sup>) achieved at room temperature with only 0.7 μm of MoTe<sub>2</sub> absorber layer along with 100 nm In<sub>2</sub>Te<sub>3</sub> BSF. This research work compares the thermal stability of the structure of MoTe2 PV cell with and without BSF. It was found that the normalized efficiency decreased in response of increasing the operating temperature at the gradient of -0.0275%/°C without BSF. For the addition of In<sub>2</sub>Te<sub>3</sub> BSF in the proposed MoTe<sub>2</sub> PV cell, the degradation of normalized efficiency was too less in the range of higher operating temperature.
16.0% Efficient Thin-Film CdS/CdTe Solar Cells
High efficiency cadmium sulfide (CdS)/cadmium telluride (CdTe) solar cells have been developed using ultrathin CdS films having a thickness of 50 nm. CdS films deposited on indium tin oxide (ITO)/#1737 glass substrates by the metal organic chemical vapor deposition technique, and CdTe films subsequently deposited by the close-spaced sublimation technique were used for the fabrication of CdS/CdTe solar cells. A photovoltaic conversion efficiency of 16.0% under Air Mass (AM) 1.5 conditions has been measured by the Japan Quality Assurance Organization.