Ga Ratio Research Articles

Unveiling the impact of Cu content on the physical properties and photovoltaic performance of solution‐processed Cu(In,Ga)Se2solar cell absorber

Cu/Ga + In (CGI) ratio in Cu(In,Ga)Se2 (CIGSe) semiconductor plays a decisive role in solar energy conversion. Investigations published so far relevant to CIGSe at different CGI values are solely based on the expensive vacuum process and as a result, there is a strong urge to explore a low-cost process. In this regard, we herein report the preparation of CIGSe at diverse CGI value from 0.70 to 0.97 by a facile and cost-effective solution process for the first time. From structural analysis, the blue shift is perceived by decreasing CGI value, which is related to shrinkage in the unit cell volume because of the reduction in the Cu content. As CGI value increases, crystal diameter of CIGSe vastly changed from nano to micro (50-1300 nm), whereas crystal shape reformed from irregular to hexagonal flake-like shape, which could be due to excessive influence of Cu content that alters nucleation and growth of crystals. Diverse CGI value modified Se/(Cu + In + Ga) ratio while Ga/(Ga + In) ratio remains unchanged. Bandgap energy is increased from 1.22 to 1.41 eV as Cu-deficiency increases. The morphological analysis showed a uniform, smooth and crack-free CIGSe films with a thickness of ~1 μm. The electrical properties of CIGSe are greatly changed. For instance, at higher CGI value (0.97), the carrier concentration is increased by five-order magnitude, whereas mobility improved by 109 times and resistivity decreased by 87 times as compared to lower CGI value (0.70). Moreover, photocurrent is markedly enhanced by six-order magnitude explicitly from nA to mA. As a proof of concept, solar cells are fabricated and power conversion efficiency significantly enhanced from 0.16% to 3.38% by altering CGI value. Hence, this work eminently evidences the importance of tuning CGI value by low-cost solution process and provides new perceptions into properties of CIGSe solar cell absorber as a function of CGI value.

Growth and Characterization of CuInGaSe2 Single Crystal

The chalcopyrite Cu(In,Ga)Se2 (CIGS) alloy system has received strong interest in recent years because of its potential for the development of high efficiency and low cost solar cells. The bandgap energy can be varied between 0.9 and 1.68 eV by composition ratio of In and Ga and the absorption coefficient is very high of abobe 105 cm-1. In our previous work1, I-III-VI2 chalcopyrite compound Cu(In0.2, Ga0.8)Se2 (CIGS) single crystal was successfully grown by traveling heater method (THM). The powder X-ray diffraction (XRD) pattern showed preferred orientations of (112), (220) and (312) planes, confirming the chalcopyrite structure. In Raman spectra, the A1 mode peaks expected for CIGS were observed, and no secondary phases were observed. The full-width at half-maximum (FWHM) of the X-ray rocking curve (XRC) for the (112) oriented CIGS single crystal is 103 arcsec. The good-quality single-phase CIGS single crystal can be obtained1). In this work, Ga-rich composition ratio CIGS single crystals could be also successfully grown by THM. At the ratio of Ga / (Ga + In) > 0.3, the CIGS changed from n-type conduction to p-type conduction. It was assumed that Se vacancies are reduced with increasing Ga ratio from the results of Energy dispersive X-ray spectroscopy. 1)Nagaoka, et al., Renewable Energy 2015, 79, 127-130.

Band Gap Engineering in Luminescence Thermometry – Pros and Cons

Luminescence thermometry and 2D imaging using luminescence thermometric phosphors are of growing interest as these non-contact and non-invasive techniques may offer important advantages in some applications. The requirements such thermometers have to fulfill depend on considered use. It is obvious that bio and medical applications points on different parameters than measurements in cryo-range and measuring high temperatures point on yet different needs. Nevertheless, high-sensitivity and low inaccuracy are always appreciated, as well as chemical stability in conditions the thermometers are to be used.One of the limitations of known luminescence thermometers is their limited range of temperatures they may measure. Obviously, some applications do not need a broad range of thermometer usability. On the other hand, presenting a good performance over a wide range of temperatures would give a versatile “all-purpose” thermometer. This might open a door for truly broad usage of such a phosphor.Trying to deliberately manage the performance of luminescence thermometers for a broad-range and accurate temperature measuring we paid attention to the bandgap engineering as a tool to achieve this goal. In this presentation, we shall focus on Lu2(Ge,Si)O5:Pr and Y3(Al,Ga)5O12:Pr powders with different Ge:Si and Al:Ga ratios, respectively. We shall discuss the advantages of bandgap engineering in luminescence thermometry and will point to possible complications this may cause. Among others, we shall show that managing the bandgap cause at the same time changes in phonons energies and these affect radiative and non-radiative processes, so important when luminescence over a broad range of temperatures is considered. Last but not least, a side effect of bandgap engineering is the change of the phosphor refractive index, also an important parameter for luminescence properties.This research was supported by the Polish National Science Centre (NCN) upon the grants #UMO-2017/25/B/ST5/00824 and UMO-2018/29/B/ST5/00420 and the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by Portuguese funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Financial support from FCT (PTDC/CTM-NAN/4647/2014, NANOHEATCONTROL - POCI-01-0145-FEDER-031469) is also acknowledged. E. Z. and L. D. C. are grateful to the Polish National Agency for Academic Exchange (NAWA) for support under the NAWA-Bekker #PPN/BEK/2018/1/00333/DEC/1 and NAWA-Ulam #PPN/ULM/2019/1/00077/U/00001 projects, respectively. Figure 1

Ga-Doped ZnO Nanostructured Powder for Cool-Nanopigment in Environment Applications.

Gallium (Ga) doped zinc oxide (ZnO) nanocrystals were successfully synthesized via a γ-radiation-assisted polymer-pyrolysis route. Ga doped ZnO samples with Ga and ZnO precursor salts with molar ratios of 0%, 3%, 5%, and 10% were produced. A γ-radiation dosage of 1.5 kGy was used for polymerization initiation during the sample preparation. The properties of the obtained nanocrystal samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-visible absorption, NIR-VIS-UV diffused reflectance, and high-resolution transmission electron microscopy (HR-TEM) characterization techniques. XRD results revealed the formation of ZnO nanocrystals with wurtzite structure for both Ga-doped and undoped ZnO samples. Noticeable increasing in the line broadening of the XRD peaks as well as pronounced decreasing of crystallite size were observed with the increasing Ga ratio in the samples. Optical peaks around Ga:ZnO samples showed a blueshift in the optical absorption peaks with increasing Ga content. These results are in good agreement with the dependency of crystallites size as well as grain size on Ga ratio obtained from XRD and TEM images, which make them fit well for the powder cool-pigment applications. The doped samples showed high values of NIR reflectance () with percentage varied from 84.25% to 89.05% that enabled them to qualify for cool-nanopigment applications. Furthermore, such doped samples registered low values of visible reflectance () that enabled to reduce the glare from the reflected visible sunlight.

Mixed-phase β-Ga2O3 and SnO2 metal-semiconductor-metal photodetectors with extended detection range from 293 nm to 330 nm

In this article, we demonstrate β-Ga2O3 and SnO2 mixed-phase thin films with dominant (2¯01)-β-Ga2O3 and (200)-SnO2 orientations on c-face sapphire (c-Al2O3) by chemical vapor deposition in a tube furnace. Transmission electron microscopy (TEM) reveals their simultaneous growth on substrate due to the small mismatches of (2¯01)-β-Ga2O3/c-Al2O3 (∼3%) and (200)-SnO2/c-Al2O3 (∼0.6%). Therefore, we also successfully demonstrate preferred-orientation (2¯01)-β-Ga2O3 and (200)-SnO2 mixed-phase thin films by controlling the Sn and Ga ratios in precursors. At 40 V, the photoelectric properties of metal-semiconductor-metal (MSM) photodetectors are modulated with more SnO2 content in mixed-phase thin films, including the dark current from 11 pA to 4 nA, the peak response in UVC from 240 nm (2 mA/W) to 260 nm (1.15 A/W), the tunable cut-off wavelength from 274 nm to 297 nm, and the extended detection range at long wavelength from 293 nm to 330 nm. Our devices show Ga2O3-like photoresponse properties rather than SnO2-like properties with lower dark current, comparable responsivity and detectivity, and faster response time than the performances of parts of the pure and mixed-phase Ga2O3-based photodetectors with untunable detection rang, which is expected to extend wider applications of other Ga2O3-based mixed-phase materials during doping or alloying, and paves a new and feasible way to realize high-performance Ga2O3-based photodetectors with controllable detection range.

The colour of crop improvement

The colour of crop improvement

In vivo biocompatibility and efficacy of dexamethasone-loaded PLGA-PEG-PLGA thermogel in an alkali-burn induced corneal neovascularization disease model

Challenges of ophthalmic drug delivery arise not only from the limited solubility of hydrophobic therapeutics, but also the restricted permeability and fast clearance of drugs due to the complex anatomy and physiology of eyes. Excellent biocompatibility of a thermosensitive polymer, PLGA-PEG-PLGA (1800–1500–1800, LA:GA ratio = 3:1), as an ophthalmic delivery system was demonstrated in our previous work. In this study, delivery of dexamethasone using this thermogel via a single subconjunctival injection for prolonged treatment was evaluated with corneal neovascularization using an alkali-burn diseased model in rat. Solubility of dexamethasone in the polymeric solution was increased by 5.2-fold and the resulting drug-loaded solution formed in situ rigid gel at body temperature. Prolonged in vitro release of dexamethasone from the gel structure was noted. Dexamethasone gel formulation was demonstrated to be more effective in reducing the burn stimulus and neovascularization in the rat diseased model. The findings suggest the PLGA-PEG-PLGA in situ gelling system can be applied for ophthalmic drug delivery to achieve sustained drug release and improved efficacy.

Detrimental copper-selenide bulk precipitation in CuIn1-xGaxSe2 thin-film solar cells. A possible reason for the limited performance at large x?

In this paper, we propose a possible explanation of the limited CuIn1-xGaxSe2 (CIGSe) performance at high Ga contents, related to the properties of detrimental copper selenide (CuδSe) secondary phases. We study CIGSe layers at different x, by means of X-ray diffraction analyses, Raman and energy dispersive X-ray spectroscopy. Our results reveal that for high Ga contents, CuδSe secondary phases either precipitate at the interfaces between grains or remain within the layer as intra- or inter-grain clusters, deteriorating the electronic properties of the absorber layer. On the contrary, for low Ga contents, the copper selenide segregates at the surface of the CIGSe and hence it can be easily removed by KCN surface etching. To understand the CuδSe precipitation within the bulk of the film for a high Ga ratio, we also investigate In-free CGSe samples at low and high Cu content. Our observations demonstrate that i) CuδSe has a preferential grain orientation to segregate and ii) the Cu-enriched regions within the bulk of the high Ga content films are more a kinetic than a thermodynamic issue.

Exploring impurity phases derived from the introduction of vanadium ions in yttrium gallium garnet

The associated impurity phases derived from the introduction of vanadium ions in yttrium gallium garnet (YGG) were investigated in detail. The XRPD data indicate that β-Ga2O3 is contained in all synthesized samples and YVO4 can be identified when the V-doped concentration above 0.5 at. %. The existence of β-Ga2O3 is related to the antisite defects usually contained in the garnet host, and the generation of YVO4 is mainly derived from its lower formation temperature in comparison to the garnet phase. The micro-area composition analysis further verifies the existence of impurity phases, and the X-ray computed tomography survey provides a more visualized spatial distribution of the YVO4 phase. Moreover, the fluorescence analysis manifests a more sensitive phase identification than the XRPD technique, and the YVO4 impurity phase can be detected even if the V-doped content is reduced to 0.2 at. %. Additionally, the evaluated V/(V + Y + Ga) ratios from structure refinement coincide well with the theoretical value in the low-doping section, and the slight deviation in the high doping part is mainly attributed to the volatilization of vanadium oxides. What discussed in this study offers a comprehensive analysis strategy for the detection of impurity phases originating from ion doping.

Gallium Doping Effects for Improving Switching Performance of p-Type Copper(I) Oxide Thin-Film Transistors.

Copper(I) oxide (Cu2O), which is obtained from copper(II) oxide (CuO) through a reduction process, is a p-type oxide material with a band gap of 2.1-2.4 eV. However, the switching performance of typical Cu2O thin-film transistors (TFTs) is poor because the reduction process increases the concentration of oxygen vacancies (VO), which interfere with the conduction of hole carriers. Ga with high oxygen affinity was doped in Cu2O thin films to decrease VO during the reduction process. As a result, the VO concentration of 1.56 at % for Ga-doped Cu2O (Ga:Cu2O) thin films decreased from 20.2 to 7.5% compared to pristine Cu2O thin films. Accordingly, the subthreshold swing or S-factor, on/off-current ratio (Ion/off), saturation mobility (μsat), and threshold voltage (Vth) of Ga:Cu2O TFTs were improved compared to pristine Cu2O TFTs with values of 7.72 from 12.50 V/dec, 1.22 × 104 from 2.74 × 102, 0.74 from 0.46 cm2/Vs, and -4.56 from -8.06 V, respectively. These results indicate that Ga plays an important role in improving the switching performance of p-type Cu2O TFT.

Precursor Reaction Method With High Ga Cu(In,Ga)(S,Se)$_{2}$ to Achieve Increased Open-Circuit Voltage

The precursor reaction process for the fabrication of Cu(In,Ga)Se $_{2}$ solar cells potentially allows for low-cost fabrication and scalable processing for manufacturing. Additionally, this process has yielded record efficiencies in lab-scale experiments. Thus far, research on the precursor reaction method has been restricted to relatively low Ga compositions with Ga/(In+Ga) $\approx$ 25%. By increasing the ratio of Ga, it is possible to increase the bandgap, and thus, increase the open-circuit voltage. This work develops and characterizes the precursor reaction process for use with Ga/(In+Ga) $\approx$ 50%, with the goal of improving the open-circuit voltage and efficiency. It is shown that with an increased Ga ratio, increased ${V}_{\rm oc}$ is achieved, but the rate of conversion from the precursor to absorber phases is decreased. Additionally, increased Ga improves the film adhesion at increased selenization temperatures as well as improving the film morphology.

Conductivity and structural properties of fast Ag-ion-conducting GaGeSbS–AgI glassy electrolytes

The use of ion-conducting chalcogenide glass, a promising solid electrolyte, is encouraged at higher conductivity for all-solid-state rechargeable battery. Herein, a new quaternary glass of GaGeSbS–AgI system was successfully prepared, and its structural and electrochemical properties were investigated by XRD, Raman, and AC impendence measurement. The relatively high conductivity of 2.955 × 10−3 S/cm and low activation energy of 0.07 eV were obtained after optimized structure regulation. The short-range schematic of the glass structure was explored to determine the fast-migrating mechanism involved in conducting Ag+ ions. By controlling the proper ratio of Ga(Ge) and Sb cations, the loose and porous layer structure of [SbSxI3-x] linking by the [Ga(Ge)S4] tetrahedron was formed, resulting in the rapid transport of Ag+ ions with a reduced migration energy barrier. The current work is the first time that a sulfide solid electrolyte in quaternary glass system with desirable electrochemical characteristics was used to address energy and safety issues.

Fabrication of Cu(In,Ga)SxSe2−x films by one-step sputtering with elevated substrate temperature and their characterization

One-step sputtering with elevated substrate temperature was used to fabricate Cu(In,Ga)Se2 (CIGSe) and Cu(In,Ga)S2 (CIGS) films. We investigated the influence of this approach on the structure and electrical properties of CIGSe and CIGS films. Compact films with large grain size were achieved at relatively low substrate temperatures below 400 °C without post-treatments. The films obtained from CIGSe targets showed larger grain and higher crystallinity compared to that prepared from CIGS targets. It was found that the substrate temperature over 400 °C brought some undesirable effects on the film quality, such as voids and secondary phases. The loss of Ga and In during the fabrication process was detected, resulting in the formation of Cu-rich films with low carrier density. HBr solution etching reduced the Cu/(In + Ga) ratio of the sputtered films, leading to the improvement of the performance of the CIGSe solar cells along with the enhancement of carrier density.

Application of the ratio of pulmonary valve ring to aortic valve ring to predict the need of transannular patch in the radical operation of tetralogy of Fallot

Objective To analyze the ratio of pulmonary valve ring to aortic valve ring (GA ratio), and to explore the application value of GA ratio in predicting the need of transannular patch in the radical operation of children with tetralogy of Fallot (TOF). Methods A retrospective analysis was performed in 355 children (182 males and 173 females) with TOF and underwent radical operation in the Pediatric Cardiac Center of Beijing Anzhen Hospital Affiliated to Capital Medical University from January 2016 to December 2017.They were divided into transannular patch group and non-transannular patch group.The values of pulmonary valve ring and aortic valve ring in two groups were collected, and the Z-score of pulmonary artery and GA ratio were calculated respectively for statistical analysis. Results Among the 355 patients, 156 children (43.9%) required a transannular patch, and 199 patients (56.1%) did not receive transannular patch.The GA ratio and the Z-score of of pulmonary artery in the transannular patch group were lower than those in the non-transannular patch group [0.45±0.12 vs. 0.54±0.15, (-1.75±0.98) scores vs.(-0.86±1.39) scores], and the differences were statistically significant (t=5.29, 6.32, all P<0.01). Receiver operating characteristic curve analysis showed that in the case of the Z-score of pulmonary artery of -2 for the children received transannular patch, the area under the curve (AUC) was 0.702 (95%CI: 0.64-0.76), sensitivity was 69%, and specificity was 83%; in the case of the GA ratio of 0.58 for the children received transannular patch, the AUC was 0.712 (95%CI: 0.66-0.77), sensitivity was 70%, and specificity was 87%. Conclusions The GA ratio is a simple and effective predictor of transannular patch in the radical operation of TOF and can be applied in clinical practice. Key words: Tetralogy of Fallot; Transannular patch; Z-score of pulmonary artery

Improved Mechanical and Electrical Properties of Phase-Change-Memory Ga-Sb Thin Films.

In this study, we focus on the mechanical and electrical properties of Ga-Sb thin films with different Sb contents; the corresponding improvement mechanism is also discussed. The phase-identification results prove that cubic GaSb phase and rhombohedral Sb phase exist in crystalline Ga-Sb thin films. Moreover, elemental Ga formed in small sizes around the boundary was observed. The resistance-temperature curves prove that the crystallization temperature (Tx) of Ga-Sb is 40 °C higher than that of Ge₂Sb₂Te5 (GST), and that Tx increased with increasing Ga content, while the resistance contrasts decreased. Consequently, the amorphous thermal stability of Ga-Sb is superior. Nanoindentation results prove that the hardness and elasticity modulus of Ga-Sb increases with increasing Ga content and is higher than that of GST thin films. In addition, structural investigation demonstrated that with different Ga contents, the hardness improvement of Ga-Sb thin films benefits from grain-size effects and the precipitation of elemental Ga in grain boundaries. Therefore, the ratio of Ga and Sb content has a different influence on the properties of both constituents. These findings indicate that binary Ga-Sb compositions are promising candidates for phase-change-memory applications.

Influence of Ga2O3, CuGa2O4 and Cu4O3 phases on the sodium-ion storage behaviour of CuO and its gallium composites.

CuO and its gallium composites with various compositions are successfully fabricated by using a hydrothermal technique followed by calcination at 900 °C. The added Ga precursors formed oxides in the composites, such as Ga2O3, CuGa2O4 and Cu4O3, as confirmed through the X-ray diffraction patterns as well as the HRTEM and SAED patterns. Further HRTEM analysis also confirmed that Cu4O3 and CuGa2O4 phases reside on the surface of CuO in the composites with a CuO : Ga ratio of 90 : 10. The contents of various oxide phases varied when we increased the amount of Ga in the CuO composites. Changing the ratios of CuO and Ga precursors in the composites is quite effective in tailoring the sodium-ion storage behaviour of CuO. The resultant CuO/Ga composites exhibit remarkable electrochemical performance for sodium-ion batteries in terms of capacity, rate capability and cycling performance. The composite containing 90% CuO and 10% Cu/Ga oxides delivers the highest charge capacity of 661 mA h g−1 at a current density of 0.07 A g−1 with a capacity retention of 73.1% even after 500 cycles. The structure and morphology of the composite (90% CuO and 10% Cu/Ga oxides) was successfully retained after 500 cycles, which was confirmed through ex situ XRD, SEM and HRTEM analyses. The composite also exhibited remarkable rate capability in which it delivered 96 mA h g−1 even at a high current density of 6.6 A g−1. The enhanced electrochemical performances of CuO and its gallium composites are attributed to the presence of Cu4O3 and CuGa2O4 phases. The Cu4O3 phase is actively involved in the redox reaction and the CuGa2O4 phase stabilizes the CuO phase and buffers the volume expansion of CuO during cycling. The present approach eplores great opportunities for improving the electrochemical performance of oxide based anode materials for sodium-ion batteries.

The investigation of molecular beam epitaxy growth of GaN by molecular dynamics simulation

The epitaxial growth of GaN on AlN substrate is investigated by using the molecular dynamics simulation. The effects of substrate rotating speed, the effusion source inclined angle, the substrate temperature and the flux ratio of Ga and N atoms are simulated and studied. The variation of the surface morphology and atomic scale structure are discussed in detail. It is observed that the roughness decreases rapidly as the rotating speed increases from 0 to 2 revolutions per monolayer. The crystalline quality is improved as the rotating speed increases from 0 to 5 revolutions per monolayer. The surface roughness keeps a small change as the incident angle increases from 15° to 45° and then increases significantly with further increase of incident angle. However, the wurtzite composition of the structure components presents a positive correlation with the incident angle. The surface morphology is much better at the N: Ga flux ratio of 0.8 than at the ratio of 1.2 and the crystalline quality at the N: Ga flux ratio of 1 is better than that at the ratio of 1.2 and 0.8 in overall trend. However, the crystalline quality at the N: Ga flux ratio of 0.8 is improved significantly and surpasses the crystalline quality at the ratio of 1 under a relatively high temperature.

Process Optimization for Extraction of Polyphenols from Avocado Seeds (Persea americana Mill.) Using Response Surface Methodology

At the present time, polyphenolic compounds have attracted great interest due to their roles in the prevention of degenerative diseases and have used as the input material for manufacturing functional foods, nutraceutical and pharmaceutical products. Previous researches have revealed the avocado seed is rich source of polyphenolic compounds with antioxidant and antimicrobial activities; which they could be used as a source of potent natural ingredients and additives. In this study, extraction factors of polyphenols were optimized for recovery yield by using response surface methodology and the obtained polyphenol rich solution was encapsulated with different coating agents (Maltodextrin-MD and Gum Arabic-GA) as well as their mixtures. A Box-behnken design was used to investigate the effects of three independent variables including ethanol concentration (X1:35-65%, v/v), solvent to solid ratio (X2:8-12, v/w) and extraction time (X3:1.0-3.0 h). The result shown that the optimized extraction conditions were using ethanol concentration of 40% (v/v), ratio of solvent to solid at 12:1 and extraction time of 1.5 h. Under the conditions, the experimental recovery yield of polyphenols is 83.1% which is well matched with the predicted yield of 82.5%. Micro particle prepared by 20:80 of MD:GA ratio as coating agent can be selected for encapsulation of the polyphenolic compounds.

The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO2/GaN Interface

Herein, the influence of the Ga–OH bond at the GaN surface on the electrical characteristics of the SiO2/GaN metal‐oxide semiconductor structure is investigated. The GaN surface is modified by three different surface treatments (O2 annealing, wet annealing, and ultraviolet [UV]/O3 treatment). The Ga–OH bond is evaluated by X‐ray photoelectron spectroscopy and characterized by capacitance–voltage (CV) measurements and a positive bias stress test. Increasing the ratio of Ga–OH bonds at the SiO2/GaN interface decreases the net fixed charge at the SiO2/GaN interface in the CV measurements and increases the voltage shift in the stress test. Therefore, the Ga–OH bond at the SiO2/GaN interface develops a negative charge and behaves as an electron trap. The undesirable influence of the Ga–OH‐related traps is reduced by low‐temperature annealing.

Amphiphilic PLGA‐PEG‐PLGA triblock copolymer nanogels varying in gelation temperature and modulus for the extended and controlled release of hyaluronic acid

ABSTRACTDifferent compositional parameters of poly(D,L‐lactic‐co‐glycolic acid)‐b‐poly(ethylene glycol) triblock copolymers (PLGA‐PEG) were varied to analyze their effect on gel formation and mechanical properties. Parameters such as hydrophilic/hydrophobic ratio (PLGA/PEG ratio), lactic acid/glycolic acid ratio (LA/GA ratio), PEG molecular weight (PEG Mw), polymer solution concentration, copolymer molecular weight (Mw), and polydispersity index (PDI) were studied in this work. For copolymers with PEG Mw of 1500 Da, gelation temperature (34–37 °C) was affected by D,L‐LA/GA ratio and Mw; while modulus was affected by LA/GA ratio, Mw, and Mn. Based on the parametric study, an injectable, thermoresponsive hyaluronic acid (HA) delivery platform was designed for ocular applications. PLGA‐PEG copolymers with D,L‐LA/GA ratio of 15/1, PLGA/PEG ratio of 2/1, PEG Mw of 1500 Da, and Mw of about 6 KDa gelled at 35 °C, were optically transparent, had a modulus less than 350 Pa and were used for HA release studies. This work also demonstrates, for the first time, an extended and controlled release of HA, beyond 2 weeks, from injectable hydrogels modified with a noncovalent interacting agent, poly(L‐lysine). Smaller PLL chains slowed down the HA release kinetics, while larger PLL chains produced a release profile similar to the nonmodified hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48678.