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n-Type SnS:Cu thin films are fabricated using chemical spray pyrolysis and are used successfully for solar cell device fabricationwith the configuration ITO/CZTS/SnS:Cu/ZnO:Al/Ag for the first time. The device has high open-circuit voltage (Voc) of 810 mV, short circuit current density (Jsc) of 0.87 mA/cm2, fill factor (FF) of 51% and an efficiency of 0.36%. Similar device structure is not reported so far. Even though the Jsc obtained is less, we could achieve a good Voc and FF value which are comparable with the parameters obtained for well established solar devices. The structural, morphological, electrical and optical properties of SnS:Cu films used for the cell fabrication are studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Scanning electron microscopy, Hall measurements and UV-Vis-NIR spectroscopy. The oxygen concentration is decreased from 49 to 8% as the Sulfur concentration is increased and hence proved that adjustment of precursor ratio is a very effective method to control the oxygen content of the samples, which is a determining factor in the performance of the device. This work suggests an easily adoptable method for preparing n-type SnS:Cu thin films favorable for device fabrication by varying tin to sulphur ratio.

Cu 2 ZnSnS 4 thin films with different tin concentration are deposited over ITO coated glass substrates using chemical spray pyrolysis technique, by adjusting [ Sn ] [ Zn ] ratio as 0.7, 1 and 1.3 in the precursor solution. As prepared films are subjected to sulfurization at a temperature of 500 °C for 15 min and its effect on the structure and composition of the films is studied. Sulfurization is carried out under non-vacuum condition inside the spray pyrolysis chamber making it compatible with the deposition technique. Pristine and sulfurized films are analysed using X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, UV–Vis–NIR spectroscopy and scanning electron microscopy. X-ray diffraction and Raman spectroscopy suggest the formation of Cu 2 ZnSnS 4 and other binary compounds in the pristine films. Analysis of the sulfurized films indicates that the sulfurization process has brought about a significant change in the composition of the films while improving its crystallinity considerably. Compositional analysis using X-ray photoelectron spectroscopy reveals that substantial amount of indium from the underlying ITO has diffused into the film after sulfurization. However, it is observed that increase in concentration of tin in the film limits the diffusion of indium. Scanning electron microscopic images show the improvement in morphology of the films after sulfurization.

In the present paper, we report the development of solution processed Carbon Nano-Tube (CNT) and PEDOT:PSS composite for application in c-Si – organic heterojunction solar cell as hole selective layers. The PEDOT:PSS CNT composite film shows high conductivity and has high optical transparency. The CNT network in the composite film will act as a carrier transport bridge between the PEDOT:PSS domains. Also, the CNT will act like stress centers preventing the breakage of transport path of carriers in composite film, making the CNT-PEDOT:PSS composite an excellent candidate as hole selective layer in flexible solar cells. Thus, the CNT-PEDOT: PSS composite can considerably enhance the performance of CNT-PEDOT: PSS /n-Si solar cells through the synergistic properties of CNT and PEDOT:PSS. The power conversion efficiency of the as-designed solar cell was 9.24% with an open circuit voltage of 576 mV. Dopant-free double heterojunction solar cell making use of MgF2 electron transport layer was also fabricated.

Polycrystalline Cu 2 ZnSnS 4 (CZTS) thin films were prepared using chemical spray pyrolysis. We examined the influence of concentration of copper in spray solution and spray rate on the properties of the films. Choice of copper concentration in the precursor solution was found to have a pivotal role in adjusting composition, band gap and resistivity of sprayed CZTS thin films. Nearly stoichiometric CZTS thin films with desirable band gap were obtained by using copper concentration of 0.015 M. Spray rate also has crucial role in adjusting properties like band gap of the films. Higher spray rates resulted in rougher films with secondary phases of copper sulfide. Secondary phases were also observed at low spray rate of 2 ml/min. Good films without any secondary phases and having band gap of 1.5 eV were obtained at the spray rate of 6 ml/min.

A double layer Cu2ZnSnS4 absorber was employed for the first time to improve the performance of spray pyrolysed Cu2ZnSnS4/In2S3 thin film solar cell. Copper concentration in the two layers of Cu2ZnSnS4 was adjusted and effect on performance parameters was studied. It was observed that higher copper concentration in the absorber layer adjacent to the electrode is beneficial for device performance, whereas, lower copper concentration in absorber layer near to the junction has detrimental effect on the device properties.

In 2 S 3 thin films have been grown on Indium Tin Oxide (ITO) by Chemical Spray Pyrolysis. The structural and physical–chemical properties of the films have been investigated by means of X-ray Diffraction and X-ray Photoelectron spectroscopy (XPS). The valence band discontinuity at the In 2 S 3 /ITO interface has been determined by XPS resulting in a value of 1.9 ± 0.2 eV. Consequently, the conduction band offset has been estimated to be 1.0 ± 0.4 eV.

In this paper, we report the results of investigations on the potential of spray pyrolysis technique in depositing electron selective layer over larger area for the fabrication of inverted bulk-heterojunction polymer solar cells. The electron selective layer (In2S3) was deposited using spray pyrolysis technique and the linear heterojunction device thus fabricated exhibited good uniformity in photovoltaic properties throughout the area of the device. An MEH-PPV:PCBM inverted bulk-heterojunction device with In2S3 electron selective layer (active area of 3.25 × 3.25 cm2) was also fabricated and tested under indoor and outdoor conditions. From the indoor measurements employing a tungsten halogen lamp (50 mW/cm2 illumination), an open-circuit voltage of 0.41 V and a short-circuit current of 5.6 mA were obtained. On the other hand, the outdoor measurements under direct sunlight (74 mW/cm2) yielded an open-circuit voltage of 0.46 V and a short-circuit current of 9.37 mA.

Polymer solar cells with configuration ITO/ZnO/P3HT:PCBM/Ag were fabricated using cost effective chemical spray pyrolysis and spin coating techniques. When surface of ZnO layer was modified with a second layer so as to increase the roughness, considerable improvement in cell parameters were observed. Optimum conditions for the required roughness were identified and changes in cell parameters with variation in surface roughness were studied. Major enhancements were observed in the open circuit voltage and in the cell efficiency.

ITO/In 2 S 3 /MEH-PPV:PCBM/Ag bulk-heterojunction device was fabricated and the effect of donor to acceptor ratio, nature of solvent and active layer thickness on the performance of the device was studied. The most favorable donor to acceptor ratio was found to be 1∶4. A significant improvement in the fill factor of the device and thereby the efficiency was observed on changing the solvent from chlorobenzene to 1,2-dichlorobenzene. The fill factor improved from 28 to 37% whereas the efficiency enhanced to 0.5%. Optimum performance was found for an active layer thickness in the range 75–100nm. Stability studies revealed that the device performance degrades monotonically under continuous irradiation. A large area device was also fabricated and showed comparable performance both under indoor and outdoor conditions. The device was stored in ambient air and tested periodically. It survived for a considerable period of time without much degradation in performance indicating the interfacial stability of the device.

Photoluminescence (PL) technique has been put into use for analysing In2S3/MEH‐PPV heterojunction for the first time. Strong luminescence of the polymer absorber MEH‐PPV has been exploited here to predict the properties of the cell. The underlying theory is the dependence of PL intensity on quasi Fermi level separation, which is a measure of the open‐circuit voltage. Predicted voltages from PL were very much in communion with those obtained from J‐V measurements. Thus the choice of PL for noninvasive analysis of solar cells can be justified from the present work.