A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 m to 0.75 m. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It is shown that the thinner CdTe layer of 0.75 m obtained the best power conversion efficiency up to 5.3%. The results of this work shows the importance that CdTe grain size/morphology relative to CdTe thickness has on device performance and quantitatively exhibits what those values should be to obtain efficient thin-film CdTe/CdS solar cells fabricated with pulsed laser deposition. Further development of this combinatorial approach could enable high-throughput exploration and optimization of CdTe/CdS solar cells.

The effect of post annealing in CdCl2 was investigated to elucidate the correlation between the evolution of the microstructure of CdTe thin films with the annealing time and the performance of CdS/CdTe thin‐film solar cells made by in situ pulsed laser deposition (PLD). It has been found that the crystallinity of the annealed film is improved considerably as the CdTe polycrystalline grains evolved into grain clusters with a dendrite structure. While longer annealing time allows larger grain size, the increased film surface roughness outweighs the benefit of the improved crystallinity, resulting in increased structural disorders, such as pinholes. In fact, the concentration of the pinholes was found to increases monotonically with annealing time when it exceeds the optimal value, resulting in degradation of device performance and yield especially when pinholes appeared near the CdS/CdTe interface. This result illustrates the importance of controlling the microstructure of CdTe film and its interface with CdS to high‐performance CdTe/CdS thin‐film solar cells.

In this work, a comparative study is presented that analyses the electrical and thermoelectrical properties of free base-Phthalocyanine (Bare-Pc) and Metallo-Phthalocyanine (MPc) molecule sandwiched between gold electrodes. The study investigates the transmission and conductance characteristics of Bare-Pc without central metal ion and with different transition metal ions at the centre of (Pc) such as (Mn, Co, Ni, and Zn) in two different molecular configurations, cis and trans. The results reveal that the conductance changed by varying the transition metal-centre in the order of Co > Ni > Zn in trans, and closely similar pattern Co > Ni > Mn in cis with higher values in trans configuration. This reflects the correlation between the spin-dependent transport properties with the transition metal-centre type and the molecular structure. Further, thermoelectrical properties such as thermal conductance (k), Seebeck coefficient (S) and figure of merit (ZT) are investigated. It was found that (k), (S) and (ZT) have higher values in case of trans configuration for Co-Pc, Ni-Pc and Zn-Pc structures. Thus, by varying the transition metal-centre type and the molecular configuration of (Pc) molecule, transport properties can be tuned to produce a good value of the transmission and electrical conductance, thermal conductance, Seebeck coefficient, and figure of merit of the (Pc) molecular junction for potential high conductance and efficient thermoelectric applications.

Anin situthermal annealing process (iTAP) has been introduced before the commonex situcadmium chloride (CdCl2) annealing to improve crystal quality and morphology of the CdTe thin films after pulsed laser deposition of CdS/CdTe heterostructures. A strong correlation between the two annealing processes was observed, leading to a profound effect on the performance of CdS/CdTe thin film solar cells. Atomic force microscopy and Raman spectroscopy show that the iTAP in the optimal processing window produces considerable CdTe grain growth and improves the CdTe crystallinity, which results in significantly improved optoelectronic properties and quantum efficiency of the CdS/CdTe solar cells. A power conversion efficiency of up to 7.0% has been obtained on thin film CdS/CdTe solar cells of absorber thickness as small as 0.75 μm processed with the optimal iTAP at 450°C for 10–20 min. This result illustrates the importance of controlling microstructures of CdTe thin films and iTAP provides a viable approach to achieve such a control.