Making use of the authors' experimental results and the evidence available in the literature, an alternative model for glass/conducting glass/CdS/CdTe/metal solar cells has been formulated. This model explains the device behaviour in terms of a combination of a hetero-junction and a large Schottky barrier at the CdTe/metal interface. The main experimental observations available to date are described and compared with the currently assumed p-n junction model and this proposed new model. It is shown that the proposed model explains almost all the experimental results more satisfactorily. The paper describes the guidelines to further increase the performance efficiencies based on the new model. Following these new guidelines, the authors have fabricated improved devices producing open circuit voltage (V oc ) values over 600 mV, fill factor (FF) values over 0.60 and the short-circuit current density (J sc ) values over 60 mA cm −2 for best devices. Although the V oc and FF could be further improved, the remarkable improvement of J sc indicates the possibility of further development of multilayer graded band gap tandem solar cells based on CdS/CdTe system.
In general, ilmenite FeTiO 3 is synthesized by solid-state reaction at very high pressure and high temperature. Synthesis of FeTiO 3 is not an easy task as the Fe 2 þ ions are not stable. Therefore, it is really challenging to prepare this material. In this work nano-ilmenite FeTiO 3 was synthesized by the sol-gel method. Structural, optical and magnetic characterizations were performed. The bandgap of FeTiO 3 was determined to be 2.8 eV showing FeTiO 3 as suitable wide bandgap material for technological applications. The FeTiO 3 nanoparticles exhibit weak ferromagnetic properties at and below room temperature. The Né el temperature was observed to be around 52 K.
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