Papers by Mustafa Habib Chowdhury
Proceedings of SPIE, Feb 11, 2010
Most of the applications of fluorescence require the use of labeled drugs and labeled biomolecule... more Most of the applications of fluorescence require the use of labeled drugs and labeled biomolecules. Due to the need of labeling biomolecules with extrinsic fluorophores, there is a rapidly growing interest in methods which provide label-free detection (LFD). Proteins are highly fluorescent, which is due primarily to tryptophan residues. However, since most proteins contain tryptophan, this emission is not specific for proteins of interest in a biological sample. This is one of the reasons of not utilizing intrinsic tryptophan emission from proteins to detect specific proteins. Here, we present the intrinsic fluorescence for several proteins bound to the silver or aluminum metal nanostructured surfaces. We demonstrate the metal enhanced fluorescence (MEF) of proteins with different numbers of tryptophan residues. Large increases in fluorescence intensity and decreases in lifetime provide the means of direct detection of bound protein without separation from the unbound. We present specific detection of individual types of proteins and measure the binding kinetics of proteins such as IgG and streptavidin. Additionally, specific detection of IgG and streptavidin has been accomplished in the presence of large concentrations of other proteins in sample solutions. These results will allow design of surface-based assays with biorecognitive layer that specifically bind the protein of interest and thus enhance its intrinsic fluorescence. The present study demonstrates the occurrence of MEF in the UV region and thus opens new possibilities to study tryptophan-containing proteins without labeling with longer wavelength fluorophores and provides an approach to labelfree detection of biomolecules.
International Energy Journal, Oct 29, 2020
The booming economy of Bangladesh in recent times has created a significant need for energy. Cons... more The booming economy of Bangladesh in recent times has created a significant need for energy. Consequently, the increasing demand for power generation has led Bangladesh to become more reliant on fossil fuels. This paper highlights the current situation of the power sector in Bangladesh, proposes practical steps that can be taken to tackle the increasing energy demands and discusses the current state of research taking place in Bangladesh regarding the development of photovoltaic solar cells and the potential for thin-film solar cells to effectively harness solar energy. The use of different kinds of plasmonic metal nanoparticles (NPs) such as core-shell NPs, NP dimers made of metallic alloys and hybrid bow-tie shaped NPs with thin-film solar cells are discussed. These nanoparticles are found to significantly improve the efficiency of thin-film solar cells. The societal, environmental, and health impact of shifting from traditional fossil fuel-based energy resources towards harnessing renewable energy, primarily solar energy using thin-film solar cells is also discussed. The paper concludes with a discussion on the economic sustainability of using such proposed high efficiency thin-film solar cells so that such technologies may help lead Bangladesh towards a cleaner, greener and more secure future.
2018 International Conference and Utility Exhibition on Green Energy for Sustainable Development (ICUE), 2018
This study compares the response of thin-film silicon and gallium arsenide solar cells to the use... more This study compares the response of thin-film silicon and gallium arsenide solar cells to the use of plasmonic metal nanoparticles for modifying their respective opto-electronic behavior. Square arrays of silver nanoparticles were placed at different inter-particle distances on top of a thin film of Silicon and gallium-arsenide substrate, respectively. The absorption of incident sunlight within each solar cell type is analyzed, and compared to the short circuit current density, open circuit voltage and the output power generated from each solar cell type due to the effect of the plasmonic nanoparticles. It is found that gallium-arsenide shows larger values than Silicon of the short circuit current generated, open circuit voltage, the fill-factor and the output power generated. These results show the effect of plasmonic metal nanoparticles to increase the optoelectronic efficiency of thin-film solar cells is not limited to only Silicon substrates but extends to other commonly used semiconductor substrates.
TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON)
This study provides the response of placing a graphene layer along with plasmonic nanoparticles o... more This study provides the response of placing a graphene layer along with plasmonic nanoparticles on top of Si substrate, which significantly increases the efficiency of the photo-voltaic (PV) cells. The advantage of using plasmonic nanoparticles has already been studied in previous studies. However, not much study has been done by using graphene layers in conjunction with plasmonic nanoparticles to improve the efficiency of solar cells. The reason behind choosing graphene is because of its high electrical and thermal conductivity, transparency, excellent flexibility, bending stability, and most importantly, thickness of one atom. Another big advantage is that graphene is inexpensive and widely available commercially. Therefore, in this study, the task was to place a layer of graphene on top of the Si substrate and at the top of this layer a single Ag nanoparticle was placed. Then, the optical absorption, short circuit current, open circuit voltage, output power, fill factor and near-field enhancementswere computed. These results due to the presence of a graphene layer below the Ag nanoparticle were compared with the results of placing Ag nanoparticle on top of the Si substrate without the presence of graphene layer. For both the cases, the diameter for Ag nanoparticle was kept at 20nm, 50nm and 100nm, respectively. After comparing these results, it was found that the use of graphene in addition to the plasmonic nanoparticles, as a layer on the Si substrate, significantly improves the efficiency of the PV cells. Further analysis was done by varying the thickness of graphene layer and it was found that the thickness of 2 nm graphene layer yields the optimum efficiency.
2019 2nd International Conference on Innovation in Engineering and Technology (ICIET)
The demand for the photovoltaic (PV) cells has increased exponentially in the last decade as sola... more The demand for the photovoltaic (PV) cells has increased exponentially in the last decade as solar energy has become extremely popular because it is environmentally friendly and relatively affordable, thus making solar energy an attractive alternative to fossil fuels. Of the many methods available to increase the efficiency/performance of PV cells, the use of plasmonic nanostructures have been have been a major focus of recent research due to their ability to significantly enhance the light absorption and other optical/electrical performance of solar cells. In this paper, plasmonic metal nanoparticles made of alloys of silver, aluminum and gold with different percentage in their composition were used to enhance the opto-electronic performance of thin-film solar cells. The alloys were studied in an attempt to harness the favorable plasmon enhancement properties of individual silver, gold and aluminum particles and create a more efficient enhancing material. The size and pitch (the edge-to-edge distance between adjacent nanoparticles in an array) of the alloy nanoparticles in an array is also varied and analyzed. The simulation results show that an alloy made of Ag-Al(10%-90%) of 100nm diameter having a pitch of 100nm gives the most favorable result when compared to other composition of the alloys or with pure metal. This conclusion was reached through the analysis of optical absorption enhancement, open circuit voltage produced, short circuit current generation, fill factor calculations, efficiency and optical near-field optical enhancement studies.
2020 IEEE Region 10 Symposium (TENSYMP)
This computational study highlights the importance of aluminum and alloys of aluminum nanostructu... more This computational study highlights the importance of aluminum and alloys of aluminum nanostructures to enhance the opto-electronic performance of thin-film solar cells. Despite having favorable optical properties and significant potential to enhance the performance of thin-film solar cells, not much work has been reported on the utility of using aluminum due to its high chemical reactivity. Hence, this study attempts to devise novel ways to overcome the chemical instability of aluminum while still harnessing its favorable optical properties by constructing alloys of aluminum with other metals in different ratios. Initially, single nanoparticles of Ag, Au and Al were analyzed where Al showed optimum results. Subsequently, dimer nanostructures were designed for the same materials and the Al-Al dimer coupled to the surface of Si thin-film solar cells generated the highest values in the performance parameters. Thereafter, alloys of aluminum were designed comprising aluminum-gold (Al-Au) and aluminum-silver (Al-Ag) with varying composition of materials in the alloy. It was seen that the dimer nanostructures where each of the individual nanoparticles were alloys of aluminum showed the optimum performance parameters from the thin-film solar cells. It was observed that increasing the amount of Au in the Al-Au alloy dampened the favorable optical properties of the Al only to a limited extent while potentially adding more chemical stability. This was regarded as a reasonable trade-off and supported the goals of this study.
2021 6th International Conference on Development in Renewable Energy Technology (ICDRET)
This computational study highlights the relevance of aluminum nanoparticles (NPs) in improving th... more This computational study highlights the relevance of aluminum nanoparticles (NPs) in improving the opto-electronic performance of thin-film solar cells. Due to its high chemical reactivity and optical absorption in the ultra-violet range, aluminum nanoparticles are not typically used in applications to improve solar cell performance, despite its attractive optical properties. Therefore, aluminum nanoparticles were coated with a thin silica shell layer that resulted in shifting the absorption properties of aluminum nanoparticles to longer wavelengths, and also aided in chemical isolation of the highly reactive aluminum nanoparticle core. The absorbing substrate of silicon thin-film solar cells were then modified with various sizes of aluminum nanoparticles with varied shell thicknesses that were placed on top of the silicon substrate and also embedded inside it. Furthermore, the nanoparticles were also placed in a “sandwich” configuration, with one particle on top of the substrate and another embedded inside it. The results showed that Al-silica core-shell nanoparticles in a “sandwich” configuration demonstrated the most improved opto-electronic performance of solar cells when compared to the other configurations studied. The results underline the feasibility of using aluminum-silica core-shell nanoparticles to significantly enhance the opto-electronic properties of thin-film solar cells.
Nanomaterials for Solar Cell Applications, 2019
Abstract While the use of metal during the initial stages of development of photovoltaic (PV) tec... more Abstract While the use of metal during the initial stages of development of photovoltaic (PV) technology was not as prevalent, research predating solar cells and development of analytical techniques and technologies has meant that metals have become an essential portion of the solar energy revolution. The fight toward achieving great energy conversion efficiencies is essential for ensuring the viability of solar cells as an alternative source of energy, and thus in this regard the advent of metallic nanostructures in increasing optical absorptions of PV cells have become instrumental. From the use of materials such as gallium arsenide, cadmium telluride, and copper indium gallium diselenide (CIGS) to being used as back reflectors and efficient contacts, metals are now considered vital to PV development. One metal nanostructure-based technology in particular has attracted scientists from all parts of the world —plasmonic solar cells. The aim of this chapter is to identify and establish the key metal nanostructure technologies that have been prevalent in PVs. A greater focus will be provided toward plasmonic nanostructures, as recent trends in research show a significant shift in interest toward this field.
The Journal of Physical Chemistry Letters, 2021
The capability of quantum dots to generate both single and multiexcitons can be harnessed for a w... more The capability of quantum dots to generate both single and multiexcitons can be harnessed for a wide variety of applications, including those that require high optical gain. Here, we use time-correlated photoluminescence (PL) spectroscopy to demonstrate that the isolation of single CdSeTe/ZnS core-shell, nanocrystal quantum dots (QDs) in Zero Mode Waveguides (ZMWs) leads to a significant modification in PL intensity, blinking dynamics, and biexciton behavior. QDs in aluminum ZMWs (AlZMWs) exhibited a 15-fold increase in biexciton emission, indicating a preferential enhancement of the biexciton radiative decay rate as compared to the single exciton rate. The increase in biexciton behavior was accompanied by a decrease in blinking events due to a shortening in the dark state residence time. These results indicate that plasmon mediated enhanced decay rates of QDs in AlZMWs lead to substantial changes in the photophysical properties of single quantum dots, including an increase in biexciton behavior.
TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON), 2019
This study involves the observation of the response of thin-film solar cells to the use of hybrid... more This study involves the observation of the response of thin-film solar cells to the use of hybrid bow-tie based plasmonic metal nanostructures of two different combinations. The first hybrid nanostructure involved two aluminum (Al) pyramidal nanoparticles facing each other with a spherical silver (Ag) nanoparticle placed in the middle (Al-Ag-Al complex) and the second hybrid nanostructure involved two silver pyramidal nanoparticles facing each other with a spherical gold (Au) nanoparticle placed in the middle (Ag-Au-Ag complex). The maximum light scattering intensity of the Al pyramidal nanoparticles studied are within the wavelength range of 400-500 nm, which is in the plasmon resonance region of Ag spherical nanoparticles and the maximum light scattering intensity of the Ag pyramidal nanoparticles studied are within the wavelength range of 500-600 nm, which is in the plasmon resonance region of the Au spherical nanoparticles. The objective of this study was to observe the opto-electronic behavior of thin-film silicon solar cells due to the effect of these two different hybrid combinations separately. The optical absorption enhancement, short circuit current density, open circuit voltage and the output power generated from the solar cell structure due to the effect of the Al-Ag-Al and Ag-Au-Ag hybrid complexes were compared. Both of these Al-Ag-Al and Ag-Au-Ag hybrid complexes elicit a more favorable response from thin-film solar cells than the case of a single silver spherical nanoparticle and a single gold spherical nanoparticle, respectively. These two hybrid nanostructures also elicit superior performance from thin-film solar cells than from a previously studied Ag-Ag-Ag hybrid bow-tie based plasmonic nanostructure.
2016 3rd International Conference on Electrical Engineering and Information Communication Technology (ICEEICT), 2016
Photovoltaic (PV) cells are important devices that can be used to convert photons into electrical... more Photovoltaic (PV) cells are important devices that can be used to convert photons into electrical energy. However, the cost of current PV devices needs to be significantly reduced and their efficiencies need to be substantially enhanced to enable large scale implementation of PV cells as sources of clean electrical energy. Surface plasmon polaritrons (SPP) in metallic nanostructures in close proximity to a Si substrate can lead to enhanced optical absorption and improved energy conversion efficiency in amorphous silicon thin-film PV devices. Optimization of this phenomenon requires a detailed characterization and understanding of the parameters that govern the underlying physical mechanisms. This paper explores the relationship between energy conversion efficiency in thin-film Si solar cells and the type of metallic nanoparticle, the size of the metallic nanoparticles, and the distance between neighboring metallic nanoparticles in a periodic array of the metallic nanoparticles deposited on top of the Si substrate. Of the different metallic nanoparticle systems studied, it is found that silver nanoparticles with diameter of 100 nm and spaced 220 nm from neighboring nanoparticles in a periodic array of the metallic nanoparticles deposited on top of the Si substrate provides the maximum increase in the generated short circuit current density (JSC).
2019 International Conference on Electrical, Computer and Communication Engineering (ECCE), 2019
This study involves the response of thin-film silicon solar cells to the use of hybrid bow-tie ba... more This study involves the response of thin-film silicon solar cells to the use of hybrid bow-tie based plasmonic metal nanostructures that modifies its corresponding opto-electronic behavior. A single set of bow-tie, one vertex of each of the two triangular (pyram-idal) silver nanoparticles facing each other with a spherical nanoparticle in the middle, were placed on top of a thin film silicon substrate. Analysis of the absorption of incident sunlight within solar cell with a spherical particle and a bow-tie based nanostructure was completed and the short circuit current density, open circuit voltage and the output power generated from the solar cell structure due to the effect of both spherical and the spherical-pyramidal hybrid plasmonic nanoparticles were compared. It has been observed that the spherical-pyramidal hybrid bow-tie based plasmonic nanostructure shows larger values than spherical nanoparticles alone in terms of the short circuit current generated, the fill-factor, open circuit voltage and the output power generated. These results show that the effect of plasmonic metal nanoparticles to increase the opto-electronic efficiency of thin-film solar cells is not limited to only spherical nanoparticles alone but extends to other rarely used plasmonic nanostructures. Furthermore, these results indicate that an appropriately designed multi-particle hybrid plasmonic nanostructures can significantly enhance the optoelectronic performance of plasmonic solar cells when compared to the enhancements generated by single type of nanoparticle-based plasmonic solar cells.
2019 IEEE Region 10 Symposium (TENSYMP), 2019
This study investigates the response of thin-film silicon solar cells to the use of core-shell me... more This study investigates the response of thin-film silicon solar cells to the use of core-shell metal-dielectric nanoparticles embedded inside the Silicon (Si) substrate to enhance their performance. Multiple arrays of these particles were placed inside the silicon substrate at three different depths to observe the changes in the performance of thin-film silicon solar cells. The absorption of the incident sunlight, the short circuit current density, open circuit voltage, fill factor and the output power generated from solar cell structure due to these embedded nanoparticles have been analyzedt It has been observed that the solar cells with the embedded core-shell nanoparticles show larger values than the bare silicon substrate in terms of the short circuit current generated, the fill-factor, open circuit voltage and the output power generatedt Funhermore, the Fab, y-Perot effect has also been observed for core-shell nanopaprticles embedded inside the silicon substrate that can have many useful applications if utilized in appropriate conditions.
2020 2nd International Conference on Advanced Information and Communication Technology (ICAICT), 2020
This computational study investigates the response of a thin-film solar cell to the use of plasmo... more This computational study investigates the response of a thin-film solar cell to the use of plasmonic metal nanoparticles of three different combinations embedded within bowtie-shaped nanoapertures etched on the surface of an absorbing Si layer. A pair of spherical metal nanoparticles were placed inside the “empty” volume of the each arm of a bowtie-shaped nanoaperture. The first configuration was formed by placing a pair of silver spherical nanoparticles inside the arms of the bowtie-shaped nanopaerture, the second configuration was formed by similarly placing a pair of aluminum spherical nanoparticles and the third configuration was formed by placing a pair of gold spherical nanoparticles, respectively. The study continued by progressively merging each of the arms of the bowtie-shaped nanoaperture into one another and thereby decreasing the center to center inter-particle distance of the embedded metal nanoparticles. The optoelectronic responses of thin-film Si solar cells due to the effect produced by these nanostructure/nanoparticle combinations were compared to a Si substrate without any such nanoapertures/nanoparticles. The results show significantly increased light absorbed, short-circuit current generated and open-circuit voltage by the Si substrate which is modified with the bowtie-shaped nanoaperture and the metallic nanoparticles when compared to bare Si substrate and nanoaperture alone.
2019 International Conference on Electrical, Computer and Communication Engineering (ECCE), 2019
This paper investigates plasmonic solar cells, with extensive focus being put on bimetallic combi... more This paper investigates plasmonic solar cells, with extensive focus being put on bimetallic combinations of nanospheres of different plasmonic metals. The metals studied were silver, gold and copper. The combinations of bimetallic nanostructures designed and analysed are Ag-Ag, Au-Au, Cu-Cu, Ag-Au and Ag-Cu, and a control simulations of dual glass nanosphere complex. The substrate chosen for the photovoltaic cell is thin-film silicon. The different metals were studied in unique combinations in order to avail a broader portion of the incident solar spectrum due to the individual plasmon resonances of the different metals in the bimetallic complex being located at different spectral regions or frequencies. Of all the configurations studied, dual Ag-Ag nanospheres were observed to be the most effective in improving the opto-electronic performance of the silicon solar cell. This conclusion was reached through analyzing optical absorption enhancement, short circuit current generation, op...
2017 International Conference on Electrical, Computer and Communication Engineering (ECCE), 2017
The use of plasmonic nanostructures in enhancing the energy conversion efficiency of solar cells ... more The use of plasmonic nanostructures in enhancing the energy conversion efficiency of solar cells has been of great interest in recent times. While much of this interest has resulted in research for analyzing the metals that are most suitable for the plasmonic nanostructures, little attention has been given to optimizing the physical parameters of the nanostructures. The nanostructures that are of particular interest to this study are periodic nanoparticle arrays placed over thin-film amorphous silicon substrate. The extent to which the periodicity of the nanoparticle array affects the energy conversion efficiency of the solar cell has not been analyzed extensively. To this end, this paper investigates the periodic nature of the plasmonic metal nanoparticle array, and the relationship of the periodicity of the plasmonic nanostructured arrays to the optical and electrical enhancement obtained from coupling the nanoparticle arrays to thin-film amorphous silicon solar cells. It was found that increasing the number of rows and columns of the plasmonic nanoparticles in the array increases the observed optical and electrical signal enhancements from the thin-film solar cell. Additionally, it was also found that the optical and electrical enhancement of the solar cell depended significantly on the orientation of the nanoparticle array with respect to the axis of the polarization of the incident radiation.
2021 IEEE Region 10 Symposium (TENSYMP), 2021
This computational study models some of the possible structural defects that may occur when fabri... more This computational study models some of the possible structural defects that may occur when fabricating homogenous metal nanoparticle arrays on top of a silicon based thin-film solar cell (TFSC) and investigates their effect on the opto-electronic performance of the cell when compared to a "perfect" array (i.e., with no structural defects). To conduct this study, an array consisting of five homogenous spherical silver nano-particles having diameter of 50nm was designed as the repeating unit in a two-dimensional homogenous nanoparticle array. Finite Difference Time Domain (FDTD) simulations were first carried out to determine the optimal pitch size (inter- particle distance) for the "perfect" array based on the highest short circuit current density generated. Subsequently, three different types of defects in the repeating unit were investigated: (i) the effect of missing particles; (ii) the effect of having different particle sizes, and (iii) the effect of addition of impurities. The results obtained showed a decrease in the performance of the solar cell with the creation of most of such defects with a few notable exceptions. The results highlight the importance of considering structural defects in arrays of plasmonic nanoparticles as an important design parameter when designing such "plasmonic" thin-film solar cells.
2021 IEEE Region 10 Symposium (TENSYMP), 2021
This computational study investigates the effect of oblique angles (non-normal incidence angles) ... more This computational study investigates the effect of oblique angles (non-normal incidence angles) of incident solar radiation on the opto-electronic performance of thin-film solar cells modified with arrays of plasmonic metal nanoparticles of varying inter-particle distances. Arrays of spherical homogenous silver nanoparticles were placed on top of a silicon absorber layer. The incident angles of solar radiation studied were 0°, 10°, 20°, 30°, 40°, and 45°, while the inter-particle distances were varied between 5-100nm. This study revealed that a large angle of incidence was favorable for shorter inter-particle distances. However, a small angle of incidence produced improved results for longer inter-particle distances. Localized surface plasmon resonance analysis showed a shift in the plasmon resonance peak wavelength with the angle of incidence of light that could support the findings of this study. It is believed that the inter-particle coupling of plasmon modes plays an important role when considering the optimal performance parameters obtained for longer inter-particle distances. The results underline the impact of oblique angles of incidence on the opto-electronic performance of thin-film solar cells and highlights the importance of considering the angle of the incident light as an important design parameter when designing "plasmonic" thin-film solar cells.
2020 2nd International Conference on Advanced Information and Communication Technology (ICAICT), 2020
This computational study investigates the enhancements in the opto-electronic performance of thin... more This computational study investigates the enhancements in the opto-electronic performance of thin-film silicon solar cells due to the use of different shapes of plasmonic metal core-silica shell nanoparticles embedded inside the Si absorbing substrate. The different shapes of the silver core-silica shell nanoparticles that were investigated in this study were cubes, cylinders, pyramids, spheres and spheroids, respectively. Due to morphology-dependent properties, various shaped nanoparticles show unique optical characteristics. The most significant enhancements in the performance of the thin-film solar cells were obtained using a pyramid shaped silver nanoparticle core that was encompassed within a hollow pyramid-shaped silica shell. The conclusion reached in this study were made through rigorous finite-difference time-domain (FDTD) simulations that calculated the plasmon resonance of the different shaped metal core-silica shell nanoparticles, optical absorption enhancement studies, short circuit current density (Jsc), open-circuit voltage (Voc), fillfactor, output power and optical near-field enhancements. The study concludes with a quick investigation of the feasibility of using a ‘sandwich’ configuration where a spherical homogeneous metal nanoparticle was placed on top of the Si absorbing layer and a metal core-dielectric shell nanoparticle was embedded inside the Si layer to further enhance the opto-electrical performance of the thin-film solar cells.
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Papers by Mustafa Habib Chowdhury