This thesis focuses on development of novel nanomaterials, including semiconductor quantum dots (QDs) and gold nanoparticles (AuNPs), for fabricating white-light emitting devices and assaying thiols in biological and environmental samples. The thesis mainly contains two divisions. One demonstrates synthesis, optical properties and white-light emissions of alloyed quantum dots and their application to light-emitting devices. The other describes to combine functionalized gold nanoparticles with capillary electrophoresis and accomplish high selectivity and ultrasensitive detection for thiols. First, through one-step aqueous synthesis, alloyed ZnxCd1¡VxSe QDs have been successfully prepared at low temperatures by reacting a mixture of Cd(ClO4)2 and Zn(ClO4)2 with NaHSe using 3-mercaptopropionic acid as a surface-stabilizing agent. The optical properties and composition of the alloyed QDs were highly dependent on the molar ratio of Zn2+ to Cd2+. With the increase in Zn content, a systematic blue shift occurred in the first exciton absorption and band edge emission. Moreover, X-ray diffraction peaks of the alloyed QDs systematically shifted to larger angles simultaneously. These systematic shifts indicated the formation of the alloyed QDs. Interestingly, among these alloyed QDs, Zn0.93Cd0.07Se QDs exhibited white-light emission with quantum yields of 12%. In addition, we discovered that we could adjust the relative strength of the band edge and trap state emissions by controlling the reaction time, thereby attain white-light-emitting QDs. Finally, we blended alloyed QDs with ultraviolet-transparent polydimethylsiloxane (PDMS) to develop a white-light, solid-state lighting device by using a 365-nm UV lamp as the pump source. In the other part of this thesis, we proposed a method for selective enrichment of thiols using Tween 20-capped gold nanoparticles (AuNPs) prior to capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF). By forming Au-S bonds, Tween 20-AuNPs can selectively extract thiols from a complicated matrix. A Tween 20 capping layer not only suppresses nonspecific adsorption, but also enables NPs to disperse in a highly-salinity solution. For analyses of aminothiols, after extraction and centrifugation, thioglycollic acid was utilized to remove aminothiols that attached to the NP surfaces. The extracted aminothiols was derivatized with o-phthalaldehyde (OPA) followed by CE-LIF. The use of this nanoprobe provided approximately 11-, 282-, and 21-fold sensitivity improvements for homocysteine (HCys), glutathione (GSH), and £^-glutamylcysteine (GluCys), respectively. Furthermore, the limits of detection (LODs) at a signal-to-noise ratio of 3 for HCys, GSH, and GluCys are 4013, 80, and 383 pM, respectively. A practical analysis of aminothiols in human urine sample has been accomplished by our proposed method. For another application to determining thiol-containing peptides, we use dithiothreitol to remove thiol-containing peptides from the NP surface through ligand exchange. The released peptides are selectively derivatized with OPA to form tricyclic isoindole derivatives. After injecting a large sample volume, the sensitivity of these peptides was improved by stacking them via using polyethylene oxide (PEO) as additive for on-line concentration and separation. As a result, LODs for GSH, GluCys, and phytochelatins (PC2 ~ PC4) were down to 0.1-6 pM. The proposed method has the lowest LODs for five peptides compared to other reported methods, and it also detect dissolve thiols in seawater in practice. Our proposed method is capable of ultrasensitive detection for thiols in biological and environmental samples.

The temperature and thermal stress distributions and variations of the high power LED module were studied in this work. The thermal-elastic-plastic 3D finite element models of MSC.marc software package are employed to simulate these performances for the high power LED module. Two high power white light LED module designs are investigated¡G one is the traditional phosphorescent silicone with blue LED module and the other is a phosphor glass lens with blue LED module. The distributions of temperature and thermal stress of in these two operating LED modules are compared and discussed. The effects of different packaging parameters¡Ge.g. bonding materials, substrate materials, lens materials on the temperature and thermal stress have also been studied in this work. The simulated results reveal that the serious thermal crack may occur for these two designs if the power of single die is over 10 watt. The simulated results also indicate that an attached fin cooler may improve these thermal crack disadvantaged significantly. The effect of fin design parameters on the peak temperature reduction has studied. A feasible fin design for the high power LED module has also been proposed.

ZnO material based hetero-junctions are a potential candidate for the design andrealization of intrinsic white light emitting devices (WLEDs) due to several advantages overthe nitride based material system. During the last few years the lack of a reliable andreproducible p-type doping in ZnO material with sufficiently high conductivity and carrierconcentration has initiated an alternative approach to grow n-ZnO nanorods (NRs) on other ptypeinorganic and organic substrates. This thesis deals with ZnO NRs-hetero-junctions basedintrinsic WLEDs grown on p-SiC, n-SiC and p-type polymers. The NRs were grown by thelow temperature aqueous chemical growth (ACG) and the high temperature vapor liquid solid(VLS) method. The structural, electrical and optical properties of these WLEDs wereinvestigated and analyzed by means of scanning electron microscope (SEM), current voltage(I-V), photoluminescence (PL), cathodoluminescence (CL), electroluminescence (EL) anddeep level transient spectroscopy (DLTS). Room temperature (RT) PL spectra of ZnOtypically exhibit one sharp UV peak and possibly one or two broad deep level emissions(DLE) due to deep level defects in the bandgap. For obtaining detailed information about thephysical origin, growth dependence of optically active defects and their spatial distribution,especially to study the re-absorption of the UV in hetero-junction WLEDs structure depthresolved CL spectroscopy, is performed. At room temperature the CL intensity of the DLEband is increased with the increase of the electron beam penetration depth due to the increaseof the defect concentration at the ZnO NRs/substrate interface. The intensity ratio of the DLEto the UV emission, which is very useful in exploring the origin of the deep level emissionand the distribution of the recombination centers, is monitored. It was found that the deepcenters are distributed exponentially along the ZnO NRs and that there are more deep defectsat the root of ZnO NRs compared to the upper part. The RT-EL spectra of WLEDs illustrateemission band covering the whole visible range from 420 nm and up to 800 nm. The whitelightcomponents are distinguished using a Gaussian function and the components were foundto be violet, blue, green, orange and red emission lines. The origin of these emission lines wasfurther identified. Color coordinates measurement of the WLEDs reveals that the emitted lighthas a white impression. The color rendering index (CRI) and the correlated color temperature(CCT) of the fabricated WLEDs were calculated to be 80-92 and 3300-4200 K, respectively.

This work establishes a solid foundation for the use of indirect band gap semiconductors for light emitting application and presents the work on development of white light emitting diodes (LEDs) in silicon carbide (SiC). Novel laser doping has been utilized to fabricate white light emitting diodes in 6H-SiC (n-type N) and 4H-SiC (p-type Al) wafers. The emission of different colors to ultimately generate white light is tailored on the basis of donor acceptor pair (DAP) recombination mechanism for luminescence. A Q-switched Nd:YAG pulse laser (1064 nm wavelength) was used to carry out the doping experiments. The p and n regions of the white SiC LED were fabricated by laser doping an n-type 6H-SiC and p-type 4H-SiC wafer substrates with respective dopants. Cr, B and Al were used as p-type dopants (acceptors) while N and Se were used as n-type dopants (donors). Deep and shallow donor and acceptor impurity level states formed by these dopants tailor the color properties for pure white light emission. The electromagnetic field of lasers and non-equilibrium doping conditions enable laser doping of SiC with increased dopant diffusivity and enhanced solid solubility. A thermal model is utilized to determine the laser doping parameters for temperature distribution at various depths of the wafer and a diffusion model is presented including the effects of Fick's diffusion, laser electromagnetic field and thermal stresses due to localized laser heating on the mass flux of dopant atoms. The dopant diffusivity is calculated as a function of temperature at different depths of the wafer based on measured dopant concentration profile. The maximum diffusivities achieved in this study are 4.61x10-10 cm2/s at 2898 K and 6.92x10-12 cm2/s at 3046 K for Cr in 6H-SiC and 4H-SiC respectively. Secondary ion mass spectrometric (SIMS) analysis showed the concentration profile of Cr in SiC having a penetration depth ranging from 80 nm in p-type 4H-SiC to 1.5 [micro]m in n-type 6H-SiC substrates respectively. The SIMS data revealed enhanced solid solubility (2.29x1019 cm-3 in 6H-SiC and 1.42x1919 cm-3 in 4H-SiC) beyond the equilibrium limit (3x1017 cm-3 in 6H-SiC above 2500 [degrees]C) for Cr in SiC. It also revealed similar effects for Al and N. The roughness, surface chemistry and crystalline integrity of the doped sample were examined by optical interferometer, energy dispersive X-ray spectrometry (EDS) and transmission electron microscopy (TEM) respectively. Inspite of the larger atomic size of Cr compared to Si and C, the non-equilibrium conditions during laser doping allow effective incorporation of dopant atoms into the SiC lattice without causing any damage to the surface or crystal lattice. Deep Level Transient Spectroscopy (DLTS) confirmed the deep level acceptor state of Cr with activation energies of Ev+0.80 eV in 4H-SiC and Ev+0.45 eV in 6H-SiC. The Hall Effect measurements showed the hole concentration to be 1.98x1019 cm-3 which is almost twice the average Cr concentration (1x1019 cm-3) obtained from the SIMS data. These data confirmed that almost all of the Cr atoms were completely activated to the double acceptor state by the laser doping process without requiring any subsequent annealing step. Electroluminescence studies showed blue (460-498 nm), blue-green (500-520 nm) green (521-575 nm), and orange (650-690 nm) wavelengths due to radiative recombination transitions between donor-acceptors pairs of N-Al, N-B, N-Cr and Cr-Al respectively, while a prominent violet (408 nm) wavelength was observed due to transitions from the nitrogen level to the valence band level. The red (698-738 nm) luminescence was mainly due to metastable mid-bandgap states, however under high injection current it was due to the quantum mechanical phenomenon pertaining to band broadening and overlapping. This RGB combination produced a broadband white light spectrum extending from 380 to 900 nm. The color space tri-stimulus values for 4H-SiC doped with Cr and N were X = 0.3322, Y = 0.3320 and Z = 0.3358 as per 1931 CIE (International Commission on Illumination) corresponding to a color rendering index of 96.56 and the color temperature of 5510 K. And for 6H-SiC n-type doped with Cr and Al, the color space tri-stimulus values are X = 0.3322, Y = 0.3320 and Z = 0.3358. The CCT was 5338 K, which is very close to the incandescent lamp (or black body) and lies between bright midday sun (5200 K) and average daylight (5500 K) while CRI was 98.32. Similar white LED's were also fabricated using Cr, Al, Se as one set of dopants and B, Al, N as another.

No description available.

Carbon nanoparticles (CNPs) have drawn great attention in the last few years owing to their unique properties such as excellent water solubility, chemical stability, inertness, low toxicity, good bio-compatibility, and tunable photo physical properties. Recently, researchers have focused on hetero atom (N, S and B) doped CNPs due to their excellent properties. These properties make the CNPs and doped CNPs as potential candidates for a wide range of applications. For example, metal ion detection in aqueous solution, bio-imaging, bio-sensing, photovoltaic devices, cleavage of deoxyribonucleic acid (DNA), and catalysis. Therefore, CNPs are alternative to inorganic semiconductor nanoparticles. However, CNPs with diameter less than 10 nm have been prepared using various approaches including top down and bottom methods. Cutting the bulk carbon from high dimensional to zero dimensional by using either physical or chemical process are classified as top down method. Bottom up method refers the conversion of organic precursor to nano-carbon by using thermal pyrolysis, microwave based hydrothermal method, cage opening of C60 molecules. In the present work, I have dealt with the facile synthesis of CNPs and different hetero atom doped carbon nanoparticles (N-CNPs, B-CNPs, and BN-CNPs) using the hydrothermal method. Based on their intriguing physical and chemical properties, these CNPs/doped-CNPs have been explored for various applications such as (i) metal-free catalysts, (ii) color tunability from red to blue and bio-imaging, (iii) ammonia sensing, (iv) white light generation, and (v) detection of picric acid (PA) in aqueous solution. Finally, I have presented 3D nanodendrites of N-CNPs and Pd NPs and their excellent catalytic mass activity for methanol electro-oxidation and ultra-fast reduction of 4-nitrophenol.

The global lighting source energy consumption accounts for about 22% of the total electricity generated. New high-efficiency solid-state light sources are needed to reduce the ever increasing demand for energy. Single-phased emitter-based composed of transparent conducting oxides (TCOs) nanocrystals and fluorescent dyes can potentially revolutionize the typical composition of phosphors, the processing technology founded on the binding of dye acceptors on the surface of nanocrystals, and the configurations of the light-emitting diodes (LEDs) and electroluminescence devices. The hybrid white-light-emitting nanomaterial is based on the expanded spectral range of the donor-acceptor pair (DAP) emission originated from the γ-gallium oxide nanocrystals via Förster resonance energy transfer (FRET) to the surface-anchored fluorescent dyes. The emission of the nanocrystals and the sensitized emission of the chromophore act in sync as an internal relaxation upon the excitation of the γ–gallium oxide nanocrystals. It extends the lifetime of the secondary fluorescent dye chromophore and the internal relaxation within this hybrid complex act as a sign for a quasi single chromophore. The model system of white-light-emitting nanostructure system developed based on this technology is the γ–gallium oxide nanocrystals-Rhodamine B lactone (RBL) hybrid complex. The sufficient energy transfer efficiency of 31.51% within this system allowed for the generation of white-light emission with the CIE coordinates of (0.3328, 0.3380) at 5483 K. The relative electronic energy differences of the individual components within the hybrid systems based on theoretical computation suggested that the luminance of the nanocomposite comprised of RBL is dominantly mediated by FRET. The production of white-light-emitting diode (WLED) based on this technology have been demonstrated by solution deposition of the hybrid nanomaterials to the commercially available ultraviolet (UV) LED due to the versatility and chemical compatibility of the developed phosphors.

The global lighting source energy consumption accounts for about 22% of the total electricity generated. New high-efficiency solid-state light sources are needed to reduce the ever increasing demand for energy. Single-phased emitter-based composed of transparent conducting oxides (TCOs) nanocrystals and fluorescent dyes can potentially revolutionize the typical composition of phosphors, the processing technology founded on the binding of dye acceptors on the surface of nanocrystals, and the configurations of the light-emitting diodes (LEDs) and electroluminescence devices. The hybrid white-light-emitting nanomaterial is based on the expanded spectral range of the donor-acceptor pair (DAP) emission originated from the γ-gallium oxide nanocrystals via Förster resonance energy transfer (FRET) to the surface-anchored fluorescent dyes. The emission of the nanocrystals and the sensitized emission of the chromophore act in sync as an internal relaxation upon the excitation of the γ–gallium oxide nanocrystals. It extends the lifetime of the secondary fluorescent dye chromophore and the internal relaxation within this hybrid complex act as a sign for a quasi single chromophore. The model system of white-light-emitting nanostructure system developed based on this technology is the γ–gallium oxide nanocrystals-Rhodamine B lactone (RBL) hybrid complex. The sufficient energy transfer efficiency of 31.51% within this system allowed for the generation of white-light emission with the CIE coordinates of (0.3328, 0.3380) at 5483 K. The relative electronic energy differences of the individual components within the hybrid systems based on theoretical computation suggested that the luminance of the nanocomposite comprised of RBL is dominantly mediated by FRET. The production of white-light-emitting diode (WLED) based on this technology have been demonstrated by solution deposition of the hybrid nanomaterials to the commercially available ultraviolet (UV) LED due to the versatility and chemical compatibility of the developed phosphors.

Organic semiconducting materials have received a lot of attention in recent years and can now be found in many applications. One of the applications, the light emitting electrochemical cell (LEC) has emerged due to its flat and lightweight device structure, low operating voltage, and possibility to be fully solution processed. Today LECs can emit light of various colors, but to be applicable in the lighting industry, white light need to be produced in an efficient way. White light on the other hand, is one of the toughest "colors" to achieve in an efficient way, and is of particular interest in general lighting applications, where high color-rendering index devices are necessary. In this thesis I show that blue light can be partially converted, into white light, by utilizing the photoluminescence of color conversion layers (CCLs). Furthermore, I show that a high color-quality white light can be attained by adopting a blue-emitting LEC with a CCL. Particularly, three different color-conversion materials were embedded onto a blue bottom-emitting LEC, to study the resulting spectrum. One of the materials, MEH-PPV, have good absorption compatibility with the electroluminescence of the blue emitters, but the materials photoluminescence do not cover the red to deep-red range of the spectrum. These parts of the spectrum are necessary to obtain high color rendering indices (≥80). A single layer of MEH-PPV adapted onto a blue-emitting LEC, led to a cold white LEC with CIE-coordinates x = 0.29, and y = 0.36, color-rendering index = 71, and correlated color temperature = 7200 K. These properties makes it potentially useful in outdoor-lighting applications. The photoluminescence of another studied color-converting material, polymer red, covers the red to deep-red range of the spectrum but the material lacks absorption in the green parts of the blue emitters electroluminescence spectrum. Thus it is necessary to combine it with MEH-PPV to be able to absorb all wavelengths from the blue-emitter and get a broad light-spectrum out of the device. In order to preserve a part of the blue light, a new device configuration was designed. It features a top-emitting blue LEC with a dual-layer CCL which reach an impressive color rendering index = 89 at a correlated color temperature = 6400 K (CIE-coordinates x = 0.31, y = 0.33). The color-rendering index is the highest reported for a white LEC. The absence of UV-, and IR-radiation, together with the high color rendering properties make the white LEC a possible candidate for even the most demanding lighting-applications, such as art galleries, and shop display windows, together with indoor lighting. In this thesis, I show that the CCLs function well. However, for the LECs to be worthy competitors, the efficiency and lifetime of the blue emitter need improvements.

Luminescent materials find numerous applications in recent times and have enriched human lives in several different ways. From display and lighting technologies to security, sensing and biological investigations, luminescent organic compounds have become indispensible and often preferred over their inorganic counterparts. The versatility of organic materials arises from their comparative low costs, ease of fine-tuning, low toxicity and the possibility to develop flexible devices. Even until very recent times, the investigations and usage of organic luminescent materials were mostly limited to solution-state properties. However, with progress of available characterisation techniques and parallel development of their usage in solid-state devices and other applications (e.g. security, forensics, sensing etc.), significantly greater attention has been paid to the development and investigations of solid-state emissive organic materials. In solid-state applications, apart from the molecular properties of any given material, their cumulative i.e. bulk physical properties are of even greater importance. Thus, investigations of structure-property relationships in organic luminescent compounds to understand their molecular and bulk properties are of fundamental interest. In this thesis, NPI (1,8-naphthalimide) and BODIPY (boron-dipyrromethene) dyes were investigated to provide a broad overview of their structure-property correlations. Among commonly encountered organic luminescent materials, NPIs and BODIPYs have emerged as two broad classes of luminescent organic compounds, finding applications as functional luminescent materials in various fields. However, lack of understanding for controlling the cumulative emissive properties of these compounds has limited their usage as active solid-state emitters in various applications. This thesis presents several new insights into the molecular and bulk emissive properties of these two classes of luminescent dyes (NPIs and BODIPYs). The contents of the six chapters contained in this thesis are summarised below. Chapter 1 summarises the available understanding of the basic concepts of photoluminescence and the design strategies to develop solid-state luminescent and AIE (aggregation-induced emission) active materials. This chapter also emphasises in the basic nature of the NPI and BODIPY compounds, their substitution patterns and their inherent characteristics and touches upon the relatively unexplored properties of NPI and BODIPY based materials. The importance and scope of the work reported in the thesis is outlined at the end of the chapter. Chapter 2 describes a detailed investigation of a series of seven (4-oxoaryl substituted) NPI compounds (1-7) providing an insight into the molecular and cumulative photophysical behaviour of these compounds. The low ICT characteristics of the NPIs, coupled with the twisted geometry, facilitated solid-state luminescence in these materials. The solution and solid-state luminescent properties of these compounds can be directly correlated to their structural rigidity, nature of substituents and solid-state intermolecular interactions (e.g. π-π stacking, C-H•••O interactions etc.). The solid-state crystal structures of the NPI siblings are profoundly affected by the pendant substituents. All of the NPIs (1-7) show antiparallel dimeric π-π stacking interactions in the solid-state which can further extend in parallel, alternate, orthogonal or lateral fashion depending on the steric and electronic nature of the C-4′ substituents. Structural investigations including Hirsfeld surface analysis methods reveal that while strongly interacting systems show weak to moderate emission in their condensed states, weakly interacting systems show strong emission yields under the same conditions. The nature of packing and extended structures also affects the emission colors of the NPIs in the solid-state. DFT computational studies were utilized to understand the molecular and cumulative electronic behavior of the NPIs. Apart from the investigation of solid-state luminescence, other functional potentials of these NPIs were also explored. One of the compounds (i.e. 4) shows chemodosimetric response towards aqueous Hg(II) species with a ‘turn-on’ response. Also, depending on the molecular flexibility of the compounds, promising AIEE (aggregation-induced emission enhancement) features were observed in these NPIs. Later (in Chapter 3), we developed a systematic investigation in a series of purely organic NPIs, restricting various parameters, to attain a thorough understanding of such AIEE properties. Chapter 3 describes a detailed experimental and computational study in order gain an insight into the AIE (aggregation-induced emission) and AIEE mechanisms in NPI compounds. Systematic structural perturbation was used to fine tune the luminescence properties of three new 1,8-naphthalimides (8-10) in solution and as aggregates. The NPIs (8-10) show blue emission in solution state and the fluorescence quantum yields depend on their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to result in quenching of fluorescence. In contrast, upon aggregation (in THF:H2O mixtures), two of the NPIs show aggregation-induced-emission-enhancement (AIEE). The NPIs also show moderately high solid-state emission quantum yields (~10-12.7 %). The AIEE behaviors of the NPIs depend on their molecular rigidity and nature of intermolecular interactions. The NPIs (8-10) show different extents of intermolecular (π-π and C-H•••O) interactions in their solid-state structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that only an optimal balance of structural flexibility and intermolecular communication is the effective recipe for achieving AIEE characteristics in these NPIs. Chapter 4 presents the design, synthesis and detailed investigations and potential applications of a series of NPI-BODIPY dyads (11-13). The NPI and BODIPY moieties in these dyads are electronically separated by oxoaryl bridges and the compounds only differ structurally with respect to methyl substitutions on the BODIPY fluorophore. The NPI and BODIPY moieties retain their optical features in these molecular dyads (11- 13). Dyads 11-13 show dual emission in solution state originating from the two separate fluorescent units. The variations of the dual emission in these compounds are controlled by the structural flexibility of the systems. The dyads also show significant AIES (Aggregation-Induced-Emission Switching) features upon formation of nano-aggregates in THF-H2O mixtures with visual changes in emission from green to red color. Whereas the flexible and aggregation prone system (i.e. compound 11) shows aggregation-induced enhancement of emission, rigid systems with less favorable intermolecular interactions (i.e. compound 12-13) show aggregation-induced quenching of emission. The emission-intensity vs. the structural-flexibility correlations were found to be reverse in solution and aggregated states. Photophysical and structural investigations suggest that the intermolecular interactions (e.g. π-π stacking etc.) play major role in controlling emission of these compounds in aggregated states. Similar trends were also observed in the solid-state luminescence of these compounds. The applications of the luminescent dyads 11-13 as live-cell imaging dyes was also investigated. Chapter 5 describes investigations of photophysical properties of a series of six BODIPY dyes (14-19) in which there is a systematic alteration of a common -C6H4Si(CH3)3 substituent. Inrelated constitutional isomers, the systematic increment of steric congestion and lowering of molecular symmetry around the BODIPY core result in a steady increment of solution and solid- state fluorescence quantum yields. The increasing fluorescence quantum yields (solution, solid state) with increasing steric congestions show that the molecular free rotation and aggregation-induced fluorescence quenching of BODIPYs can be successfully suppressed by lowering the flexibility of the molecules. Photophysical and DFT investigations reveal that the electronic band gap in any set of these constitutional isomers remain almost similar. However, the crystal structures of the compounds reveal that the solid-state colour and quantum yields of the compounds in solid-state are also related to the nature of intermolecular interactions. Chapter 6 demonstrates the use of DFT computational methods to understand the effect of alkyl groups in governing the basic structural and electronic aspects of BODIPY dyes. As demonstrated in Chapter 4 and Chapter 5, apparently electronically inactive alkyl groups can be of immense importance to control the overall photophysics of BODIPYs. In this context, a systematic strategy su was utilized considering all possible outcomes of constitutionally-isomeric molecules to understand the effects of alkyl groups on the BODIPY molecules. Four different computational methods were employed to ascertain the unanimity of the observed trends associated with the molecular properties. In line with experimental observations, it was found that alkyl substituents in BODIPY dyes situated at 3/5-positions effectively participate in stabilization as well as planarization of such molecules. Screening of all the possible isomeric molecular systems was used to understand the individual properties and overall effects of the typical alkyl substituents in controlling several basic properties of such BODIPY molecules.