Optimisation of pH of the CdCl2+Ga2(SO4)3 activation step of CdS/CdTe based thin-film solar cells

In order to produce high efficiency solar cells based on CdTe, CdCl2 post-growth treatment is an essential processing step. This treatment can be further improved by adding elements such as Fluorine and Gallium into the CdCl2 solution. Through systematic experimentation, it has been found that the pH value of the treatment solution also affect the conversion efficiency of the solar cells. This work therefore focuses on the effect of pH value of CdCl2+Ga2(SO4)3 aqueous solution on the device efficiencies. The graded bandgap device structure, glass/FTO/n-ZnS/n-CdS/n-CdTe/Au was used in this work. The pH values of 1.00, 2.00 and 3.00 for CdCl2+Ga2(SO4)3 solutions were utilised for the activation of glass/FTO/n-ZnS/n-CdS/n-CdTe layers and its effects were explored for both the CdTe material and device properties. It has been found that both CdTe material properties and solar cell device properties are superior when the pH value of 2.00 is used for post-growth treatment. The best conversion efficiency observed in this work for the above graded bandgap device is 12.2%

The influence of ZnS crystallinity on all-electroplated ZnS/CdS/CdTe graded bandgap device properties

Electrodeposition of zinc sulphide (ZnS) was achieved from electrolytic bath containing zinc sulphate monohydrate (ZnSO4·H2O) and ammonium thiosulphate ((NH4)2S2O3) in a two-electrode electroplating configuration. The cyclic voltammetric studies show that ZnS layers can be electroplated between (1350 and 1550) mV. The grown layers were characteristically explored for their structural, optical, morphological and electronic properties using X-ray diffraction (XRD) and Raman spectroscopy, UV–Visible spectrophotometry, scanning electron microscopy (SEM), photoelectrochemical (PEC) cell and DC conductivity measurements respectively. The structural analysis shows that crystalline ZnS can be deposited within a narrow cathodic deposition range between (1420 and 1430) mV. The UV–Visible spectrophotometry shows that the bandgap of both as-deposited and heat-treated ZnS films are in the range of ~(3.70 and 3.90) eV. The SEM shows small grains depicting the wetting property of ZnS. The PEC results show that the electroplated ZnS below 1425 mV is p-type and above 1425 mV is n-type under both as-deposited and heat treated condition. The DC conductivity shows that the highest resistivity is at the inversion growth voltage (Vi) for the ZnS layers. The glass/FTO/n-ZnS/n-CdS/n-CdTe/Au devices were fabricated using crystalline-ZnS and amorphous-ZnS buffer layers. The devices were explored using current-voltage (I-V) and capacitance-voltage (C-V) techniques. As expected, devices fabricated with c-ZnS show improved device parameters (ideality factor n=1.60, depletion width W=1092 nm, open-circuit voltage Voc=730 mV, short-circuit current density Jsc=34.1 mAcm-2, fill factor FF=0.57, conversion efficiency η=14.2%) when compared to device parameters (n=1.85, W=900 nm, Voc=720 mV, Jsc=29.9 mAcm-2, FF=0.52, η=11.2%) of these devices fabricated with a-ZnS buffer layers

Effect of the inclusion of Galium in normal Cadmium chloride treatment on electrical properties of CdS/CdTe solar cell

The inclusion of gallium into the well-known CdCl2 post-growth treatment shows drastic improvement in both CdTe material and electrical properties of the fully fabricated CdS/CdTe-based solar cell as compared with the regular CdCl2 treatment. The optical, morphological, compositional and electronic properties the glass/FTO/n-CdS/n-CdTe/p-CdTe were explored after post-growth treatment of glass/FTO/n-CdS/n-CdTe/p-CdTe with CdCl2 and CdCl2:Ga treatments at 430 °C for 20 min. Morphological analysis show grain growths within the ranges of (100 – 2000) nm and (200 – 2600) nm for CdCl2 and CdCl2:Ga treatments as compared with the as-deposited glass/FTO/n-CdS/n-CdTe/p-CdTe layer with grain size within the ranges of (100 – 250) nm. Structurally, the preferred orientation of the as-deposited CdTe remains (111)C after both CdCl2 and CdCl2:Ga treatments of glass/FTO/n-CdS/n-CdTe/p-CdTe with randomisation of crystallite orientation observed after CdCl2:Ga with an increase in the diffraction intensities of the (220)C and (311)C CdTe peaks. The multilayer structure glass/FTO/n-CdS/n-CdTe/p-CdTe utilised in this work was grown using electrodeposition technique. The glass/FTO/n-CdS/n-CdTe/p-CdTe sample was divided into three sets; the first and second sets were treated with CdCl2 and CdCl2:Ga respectively, while the third set was left as-deposited. Both the CdCl2 and CdCl2:Ga sets were heat treated in air at 430°C for 20 min, etched to improve metal/semiconductor interface and metallised with 100 nm Au contacts. The current-voltage measurements show comparative improvements in the open-circuit voltage, short-circuit current density, fill factor and the solar cell efficiency of the CdCl2:Ga treated glass/FTO/n-CdS/n-CdTe/p-CdTe as compared with the CdCl2 treated structure. A conversion efficiency of ~11% was achieved with the CdCl2:Ga treatment while ~7% was achieved with the CdCl2 treatment of similar glass/FTO/n-CdS/n-CdTe/p-CdTe device structure. This observation shows that the inclusion of gallium further improves CdCl2 treatment of CdS/CdTe-based solar cell due to its unique features of improving the stoichiometry of the CdTe layer

Ga doping of nanocrystalline CdS thin films by electrodeposition method for solar cell application: The influence of dopant precursor concentration

Ga doping of CdS thin films has been achieved using a simplified cathodic electrodeposition method and with glass/ indium tin oxide (glass/ITO) as a substrate. CdCl2, Na2S2O3 and GaCl3 were used as precursors. The Ga-doped and un-doped CdS films obtained were characterized for their structural, optical, luminescence, compositional and morphological properties using stateof-the-art X-ray diffraction (XRD), spectrophotometry, room-temperature photoluminescence (PL), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), respectively. XRD results show that the presence of Ga ions in the deposition electrolyte and post-deposition annealing promote crystallinity of deposited CdS films, with estimated crystallite sizes of the films in the range (5 – 22) nm after annealing. Optical characterization results show that incorporation of Ga atoms into the crystal lattice of CdS results in increase in energy bandgap of the films, which makes them advantageous for application as window/buffer layers in solar cells. PL results show a single green emission peak whose intensity increases as Ga-content of the films increases. EDX results show a direct relationship between the percentage atomic Ga composition of the CdS:Ga films and the molar concentration of GaCl3 in the deposition electrolyte. SEM images reveal smooth surfaces of doped and un-doped CdS films. However, after annealing, cracks begin to develop in the films grown with electrolytic GaCl3 concentration in excess of 0.004 M, thus indicating a possible threshold in GaCl3 concentration for obtaining device-grade CdS:Ga films. The entire work presents one of the strengths of electrodeposition as a reliable semiconductor growth technique for device application

An Evaluation of the Relationship Between Integrated Rural Development Scheme, Livelihood Assets and Housing Condition in Nigeria

The paper examined the relationship among integrated rural development scheme, livelihood assets and housing condition in selected rural areas in Osun state. This is necessitated by the need to look at an alternative ways of financing rural housing through self-help project. It is also inspired by the need for sustainability in better housing condition in the rural communities.The paper carried out a survey of participants of an existing integrated scheme that was established with the objective of improving farmers’ welfare through improved productivity in 28 rural communities under the jurisdiction of Justice Development and Peace Makers’ Centre (JDPMC), Osogbo, Osun state.  Data was obtained from 344 respondents selected through a multi-staged sampling across 28 rural communities in Osun state. The data obtained was analysed with the use of frequency distribution, correlation, regression and chi-square analysis.The results of the study in this paper reveals, among others, that the mode of operation and housing condition has positive relationship and are not independent of each other. Similarly, there is significant relationship between household size (r = 0.327) and housing condition, livelihood assets (r = 0.451) and housing condition at P ≤ 0.01. Based on these findings, integrated scheme has positive relationship with housing condition because the more the livelihood assets through integrated scheme, the better the rural housing condition in Nigeria.The paper therefore suggests consideration of integrated scheme as an effective strategy for rural housing improvement. The study is a pioneering attempt at establishing whether increase in participants’ assets such as physical, financial, natural, human and social capital due to the integrated scheme will lead to significant improvement in housing condition. Keywords: relationship, integrated, rural development scheme, livelihood assets, housing condition, and rural areas. DOI: 10.7176/CER/12-5-06 Publication date:May 31st 202

Wildlife conservation and agrarian economy in communities around Kainji Lake National Park, Niger State, Nigeria

This study was carried out to assess the wildlife conservation and agrarian economy in communities around Kainji lake national park of Niger state  Nigeria. The study was carried out in ten (10) randomly selected villages around Kainji Lake National Park namely (Luma, Kemenji, Kuble, New- Awuru, Old-Awuru, Dekera, Wawa, Woro, Malale, and Old Bussa). A total of 20 Questionnaires were administered in each community. Data was analysed using simple percentages, frequency counts and tables. The results revealed that most of the respondents (51.5%) engaged in farming for food production and income generation while about 31% of them engaged in farming for income generation only. Damages and destructions  caused by wild animals to crops in the study area is high and causes significant danger to the agrarian economy. Wild animals such as Hippopotamus (34.5%) raided the crop farms most, closely followed by Baboons (32.5%) and Patas monkey (24.5%). Farmers in retaliation adopted lethal methods such as using toxic chemicals (34%) and hunting (27.5%) to safeguard their crops. This study showed that conflict between man and animal is a serious problem in communities around conservation areas and this requires an urgent intervention to save animal in the study area  from extinction. Keywords: Wildlife, Conservation, Agrarian economy, Hunting and Extinction

Determinants of Income Distribution in the Nigeria Economy: 1977-2005

The study carried out an investigation of a number of factors which determine income distribution in Nigeria by making empirical analysis of the relationship between the determinants and income distribution using the cointegration technique. The empirical findings in the study revealed that, Gini Coefficient is very high in Nigeria, indicating a high level of income inequality. Also, employment rate, inflation rate, Gross Domestic Product and social spending were true determinants of income distribution in the Nigerian economy during the period under review (1977-2005). The study also found that, both the growth rate of output and government health expenditure exhibited an inverse relationship with Gini coefficient of income distribution in the Nigerian economy while employment rate, inflation rate and government education expenditure had direct relationship with Gini coefficient of income distribution in the Nigerian economy. Moreso, the findings showed the existence of a long run relationship between income distribution and its determinants in Nigeria. Finally, from the empirical findings in this research work and based on the relationship each determinant exhibited with the Gini coefficient of income distribution in Nigerian economy, a set of policy ecommendations were made such as: government ensuring the formulation and implementation of more pragmatic employment policies in Nigeria, government ensuring proper monitoring of its spending on education and health through appropriate policy measures and policies that bring about more equitable distribution of income and associated income earning opportunities were suggested among others.Key words: Income distribution; Inegquate; Gini coefficient enploment rate; Nigeria econom

Corporate Image: A Strategy for Enhancing Customer Loyalty and Profitability

Organizations are nowadays concerned with managing their corporate image. There is a strong positive correlation between people’s perceptions of a company and pro-corporate supportive behaviour. In this study, past researchers on corporate image were incorporated to create a platform for framework which identifies the variables of relationship between corporate image and customer loyalty cum profitability. The study utilized descriptive statistics, bivariate correlation and linear regression to investigate the impact of corporate image on customer loyalty and profitability within the Nigerian service industry (banking). The study adopted the research instrument of self-structured questionnaire which was in line with the reviewed literature and focused on the main variables in the study. It was found in the model parameters that physical environment, service offering and customer loyalty have significant impact on the level of profitability. Thus, we can rightly conclude that the level of satisfaction among customers tends to affect the service offerings and customer loyalty which has a direct link with corporate profitability

Perception of farmers on agroforestry systems adoption in Akinyele Local Government Area, Ibadan, Oyo State, Nigeria

The study assessed farmers’ characteristic variables and perception towards the adoption of agroforestry practices in Akinyele Local Government, Ibadan, Oyo State. Multistage Sampling Technique was used for the study. Five Wards which include Ijaye /Ojedeji, Ajibade/Alabata/Elekuru,  Akinyele/Isabiyi/Irepodun, Ojo Emo/Moniya and Ojoo/Ajibode/Laniba were randomly selected from the Local Government Area. Ajeja, Alabata, Akinyele, Moniya and Idowu oko areas were selected from each of the Wards, respectively while ten (10) farmers were selected from each of these areas. Descriptive statistics such as frequency and percentage distributions as well as correlational studies were used to analyse the collected data. 34 % of the respondents were involved in the practice of agroforestry according to the study. The correlation (r value) at (p< 0.01) also shows that there is a significant association between respondents’ characteristic variables such as age, educational and marital status and adoption of agroforestry practices, while age, sex, marital and educational status are significant on agroforestry perception. It is recommended that awareness  on benefits of agroforestry should be raised in order to create needed awareness and its importance, adequate technical supports should be  provided for farmers interested in practicing agroforestry and also the efficient use of available farmlands of all types of landholders should be  ensured. Keywords: Farmers’ characteristic variables; Perception; Adoption; Agroforestry practices