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Purusothaman, Yuvasree,Alluri, Nagamalleswara Rao,Chandrasekhar, Arunkumar,Vivekananthan, Venkateswaran,Kim, Sang-Jae American Chemical Society 2018 The Journal of Physical Chemistry Part C Vol.122 No.23
<P>In contrary to the existing externally powered photodetectors, a reliable approach for self-powered photodetection is designed for the first time through an internally integrated concept via coupling of piezotronic with photonic effects. A flexile self-powered photodetector (F-SPPD) developed by one-dimensionally grown floral-like F-ZnO nanorods on a poly(vinylidene difluoride) substrate conjointly performs the tunability of optical properties through the exploitation of strain-induced piezoelectric potentials (σ<SUP>+</SUP>, σ<SUP>-</SUP>) at the electrode interfaces. The experimental observation showed an ideal photodetector characteristics with a 1-fold increment in photoresponsivity (<I>R</I><SUB>365nm</SUB> ∼ 22.76 mA/W) by lowered Schottky barrier heights (Φ<SUB>SB1</SUB><SUP>T</SUP>, Φ<SUB>SB2</SUB><SUP>T</SUP>) through externally governed tensile strain (+ε). Further, the self-powered operation mode of F-SPPD exhibited higher spectral sensitivity (5.69 mA/(W cm<SUP>-2</SUP>)) than that of the photodetector (3.47 mA/(W cm<SUP>-2</SUP>)) operated under unstrained condition. This work effectively brings in the direct integration ideology of two different systems into a single module toward the downscaling of device size and weight.</P> [FIG OMISSION]</BR>
Purusothaman, Yuvasree,Alluri, Nagamalleswara Rao,Chandrasekhar, Arunkumar,Kim, Sang-Jae Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.2
<P>Herein, we report the unsymmetric effect on the functional (piezoelectric and semiconducting) properties of cadmium-doped 1D-ZnO nanorods (NRs), which have a higher ionic radius (0.97 Å). The growth of Cd-ZnO NRs, which have a hexagonal wurtzite structure without any secondary CdO phases, along the<I>c</I>-axis was confirmed by the XRD patterns, and oxidation states observed from XPS analyses verified the diffusion of Cd<SUP>2+</SUP>into ZnO NRs. A one-fold reduction in the piezoelectric properties was determined by the fabrication of a nanogenerator, and enhancement in the semiconducting properties was studied using an Ag/Cd-ZnO NRs/Ag device with various wt% of Cd doped into the ZnO NRs lattice. Cd-ZnO NRs improve the photogenerated charge carriers (<I>I</I>ph∼ 330 μA) compared to pure ZnO NRs (<I>I</I>ph∼ 213 μA), obtained at a bias voltage of 10 V, a wavelength of 365 nm and a light intensity of 8 mW cm<SUP>−2</SUP>. The Cd-ZnO NRs (1 wt%) based sensor shows good photoresponse with a detectivity (<I>D</I>*) limit of 1 × 10<SUP>11</SUP>cm H<SUP>1/2</SUP>W<SUP>−1</SUP>compared to that of pure ZnO NRs (<I>D</I>* = 5.4 × 10<SUP>10</SUP>cm H<SUP>1/2</SUP>W<SUP>−1</SUP>). We also demonstrate a self-powered UV sensor (SPUV-S) connected parallel to the ZnO NRs based nanogenerator as an independent power source to drive the Cd-ZnO NRs UV sensor. The low-temperature hydrothermal synthesis of Cd-ZnO NRs is simple, cost-effective, and scalable for industrial applications.</P>
Purusothaman, Yuvasree,Alluri, Nagamalleswara Rao,Chandrasekhar, Arunkumar,Kim, Sang-Jae Elsevier 2018 Nano energy Vol.50 No.-
<P><B>Abstract</B></P> <P>Antimony sulfoiodide (SbSI) has been demonstrated to act as an effective energy harvester due to its ferroelectric-semiconductor characteristics. This has furthered the advancement of futuristic self-powered optoelectronic devices. We studied the feasibility of designing an SbSI-based piezoelectric nanogenerators (PNGs) with polymer matrix interfaces, such as polydimethylsiloxane (PDMS), polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA). SbSI/PMMA composites exhibit promising states with respect to the potential establishment of SbSI/PMMA piezoelectric nanogenerator (S-PNG). Furthermore, as-fabricated S-PNG is highly stable, with an average peak to peak electrical response of ~ 5 V and 150 nA. The employment of SbSI overcomes the limitations of PNGs made of insulator materials, enabling the generation of dual harvesters. The piezo-phototronic properties of SbSI/PMMA composite and single SbSI micro rod (SMR) were extensively investigated. These harvesters incorporate both mechanical and optical sources, thereby providing broad opportunities for the expansion of piezoelectronic material systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new type of ferroelectric-semiconductor material, Antimony sulfoiodide (SbSI) is explored as an efficient candidate for piezoelectric nanogenerator (S-PNG). </LI> <LI> Hypothesis of polymeric composite interfaces with SbSI is proposed validating the suitability for the development of efficient S-PNG. </LI> <LI> Realization of piezoelectric and piezo-phototronic properties owned by SbSI open up the potential for the construction of hybridized devices with multifunctional sensory units. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Photoactive piezoelectric energy harvester driven by antimony sulfoiodide (SbSI)</P> <P>[DISPLAY OMISSION]</P>
Chandrasekhar, A.,Alluri, N.,Vivekananthan, V.,Purusothaman, Y.,Kim, S. J. Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.6
<P>Wearable gadgets have attracted consumer attention, resulting in an abundance of research on the development of self-powered devices. Recently, triboelectric nanogenerators (TENGs) have been shown to be an effective approach for scavenging biomechanical energy. An innovative, cost-effective and eco-friendly freestanding smart backpack-triboelectric nanogenerator (SBP-TENG) is presented for scavenging biomechanical energy. A new approach to creating irregular surfaces on a polydimethylsiloxane (PDMS) film is demonstrated by recycling a plastic Petri dish discarded after laboratory usage. The SBP-TENG relies on contact and separation electrification between the PDMS film and contact materials (wool, paper, cotton, denim and polyethylene). The performance of single-and multi-unit SBP-TENGs is systematically studied and real-time energy harvesting from human motions, such as walking, running and bending, is demonstrated. This study confirms that the SBP-TENG is an excellent technology for scavenging biomechanical energy, capable of driving a variety of low-power electronic devices such as global positioning system (GPS) sensors, wearable sensors and flashlights.</P>
Vivekananthan, Venkateswaran,Alluri, Nagamalleswara Rao,Purusothaman, Yuvasree,Chandrasekhar, Arunkumar,Selvarajan, Sophia,Kim, Sang-Jae American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.22
<P>In contrast with the conventional ceramic/oxide humidity sensors (HSs), a self-powered piezoelectric biopolymer HS with reasonable sensitivity, reliability, and a nontoxic and eco-friendly nature is highly desirable. A piezoelectric nanogenerator (PNG)-driven biopolymer-based HS provides a pathway toward a sustainable and greener environment in the field of smart sensors. For that, a piezoelectric collagen nanofibril biopolymer coated on to a cotton fabric has dual functionality (energy harvesting and sensor). Collagen PNG generates a maximum of 45 V/250 nA upon 5 N and can also work as a sensor to measure various percentages of relative humidity (% RH). The HS shows a linear response with a good sensitivity (0.1287 μA/% RH) in the range of 50-90% RH. These results open a field of eco-friendly multifunctional nanomaterials toward the development of noninvasive, implantable smart bio-medical systems.</P> [FIG OMISSION]</BR>
VENKATESWARAN VIVEKANANTHAN,Woo Joong Kim,Nagamalleswara Rao Alluri,Yuvasree Purusothaman,Gaurav Khandelwal,김상재 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5
The increasing interest in harvesting mechanical energy from day-to-day activities is gaining huge interest among researchers. We have fabricated a triboelectric nanogenerator (TENG) made of aluminum and PDMS film acting as positive and negative triboelectric layers. The layers are arranged in an arc-shaped structure with an air gap of 1 cm between the layers of the device. The PDMS layer is made by blending the polymer solution with the hardener in an appropriate ratio and dried to make the transparent and flexible polymer film. The device shows a maximum electrical response of 110 V and 260 nA voltage and current with the power density of 2.9 mW/m 2 at 100 MΩ load resistance. Further, the device has been used for lighting green LEDs and charging commercial capacitors. An Arduino board was connected with LED and buzzer, which was triggered by the TENG device. This shows that with the proper usage of electronic components TENG can be used for self-powered sensors and with IoT applications.