01171nas a2200157 4500008004100000245007900041210006900120260000800189300002300197490000700220520061800227100002200845700001900867700001900886856010800905 2006 eng d00aElectrical bistability in a xanthene class molecule: conduction mechanisms0 aElectrical bistability in a xanthene class molecule conduction m cOCT aArticle No: 1421100 v893 a

The author study conduction mechanism in two conducting states of a bistable device at range. They find that in the electrical bistable devices, electrical switching is associated with a change in the conduction mechanism. Device current in the low-conducting state follows an injection-limited mechanism. The current in the high-conducting state conforms a bulk-dominated mechanism, namely, space-charge limited conduction with an exponential distribution of traps. The bistability has an associated memory phenomenon. The devices exhibit read-only and random-access memory applications for several hours.

1 aRath, Arup, Kumar1 aSahu, Satyajit1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/electrical-bistability-xanthene-class-molecule-conduction-mechanisms01212nas a2200145 4500008004100000245007300041210006900114260000800183300001400191490000700205520072000212100002200932700001900954856009300973 2007 eng d00aConductance switching in an organic material: from bulk to monolayer0 aConductance switching in an organic material from bulk to monola cSEP a9831-98350 v233 a

Fluorescein sodium, which does not exhibit electrical bistability in thin films, can be switched to a high conducting state by the introduction of carbon nanotubes as channels for carrier transport. Thin films based on fluorescein sodium/carbon nanotubes display memory switching phenomenon among a low conducting state and several high conducting states. Read-only and random-access memory applications between the states resulted in multilevel memory in these systems. Results in thin films and in a monolayer (deposited via layer-by-layer assembly) show that instead of different molecular conformers, multilevel conducting states arise from the different density of high conducting fluorescein molecules.

1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/conductance-switching-organic-material-bulk-monolayer01383nas a2200169 4500008004100000245014600041210006900187260000800256300001600264490000700280520071200287100002200999700001901021700002201040700001901062856013201081 2008 eng d00aNanowires of metal-organic complex by photocrystallization: a system to achieve addressable electrically bistable devices and memory elements0 aNanowires of metalorganic complex by photocrystallization a syst cMAY a5937–59410 v243 a

A new method has been achieved to form a Cu:benzoquinone derivative (DDQ) charge-transfer complex by the photoexcitation of [Cu(DDQ)2(CH3COO)2] (1) that has been synthesized by the reaction of DDQ and hydrated cupric acetate in acetonitrile. Photoexcitation of coordinated complex 1 leads to the formation of charge-transfer complex Cu2+(DDQ•−)2 (2). The charge transfer complex 2, when spun on solid substrates, forms nanowires. Sandwich structures of 2 exhibit electrical bistability associated with memory phenomenon. Read-only and random-access memory phenomena are evidenced in nanowires of 2 providing a route to attend the issues pertaining to the addressibility of organic memory devices.

1 aRath, Arup, Kumar1 aDhara, Koushik1 aBanerjee, Pradyot1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/nanowires-metal-organic-complex-photocrystallization-system-achieve-addressable-electrically01195nas a2200145 4500008004100000245009400041210006900135260000800204300001400212490000600226520065500232100002200887700001900909856012100928 2008 eng d00aResistive switching in rose bengal and other xanthene molecules is a molecular phenomenon0 aResistive switching in rose bengal and other xanthene molecules  cFEB a495–5000 v93 a

There has been a debate on the mechanism of resistive switching in Rose Bengal and other Xanthene class molecules. While some authors proposed that the switching was due to an oxide layer at the Rose Bengal/Aluminum interface, some inferred the switching as an extrinsic effect like filament formation. We show results from Rose Bengal and other Xanthene class molecules on doped Si. Conductance switching in such monolayers induced by Pt/Ir tip of a scanning tunneling microscope (STM) in a non-contact mode shows that resistive switching in these molecules, initially reported by us in 2003 (in thin films), is indeed a molecular phenomenon.

1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/resistive-switching-rose-bengal-and-other-xanthene-molecules-molecular-phenomenon02049nas a2200157 4500008004100000245011700041210006900158260000800227300001600235490000700251520144300258100001901701700002201720700001901742856013001761 2009 eng d00aHybrid core-shell nanoparticles: photoinduced electron-transfer for charge separation and solar cell application0 aHybrid coreshell nanoparticles photoinduced electrontransfer for cOCT a5292–52990 v213 a

We report growth and formation of hybrid core−shell nanoparticle systems, where photoinduced electron-transfer takes place from the II−VI semiconducting core to an organic shell. With the hybrid core−shell nanoparticles, we fabricate devices so that the photoinduced electron-transfer can finally yield photocurrent and result photovoltaic solar cells. Formation of an organic shell-layer on CdSe nanoparticles is supported by electronic absorption spectroscopy. Electron-transfer from the nanoparticle in the core to a number of organic molecules in the shell is established from quenching of photoluminescence intensity of CdSe nanoparticles as well as from a change in the lifetime of photoluminescence emission. Devices based on the hybrid core−shell nanoparticles in a suitable hole-transporting layer with two dissimilar metal electrodes show efficient photovoltaic performance. Here, following the electron-transfer, electrons flow through the organic molecules and holes, left in the nanoparticles, move through the hole-transporting polymer to the opposite electrodes to yield photovoltaic short-circuit current. The role of CdSe nanoparticles in light-harvesting and charge-generation has been substantiated by control experiments with ZnS nanoparticles in the core. In ZnS-based hybrid core−shell systems, photovoltaic performance is low since photoinduced electron-transfer does not occur from ZnS to the dye.

1 aGuchhait, Asim1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/hybrid-core-shell-nanoparticles-photoinduced-electron-transfer-charge-separation-and-solar01262nas a2200145 4500008004100000245009500041210006900136260000800205300001600213490000700229520071400236100002200950700001900972856012500991 2009 eng d00aInduce negative differential resistance in organic devices through a ferroelectric polymer0 aInduce negative differential resistance in organic devices throu cJUN a1116–11190 v103 a

We report how ferroelectric materials induce negative differential resistance (NDR) in organic devices. Fluorescein, which exhibits semiconducting current–voltage characteristics, shows NDR effect in a ferroelectric matrix. Here, we vary the concentration of fluorescein in the ferroelectric matrix to study its effect on NDR. We also show how the degree of polarization controls NDR. We infer that under a suitable bias, the ferroelectric polymer becomes polarized to facilitate electron-injection in the device followed by a double-reduction of fluorescein molecules. From the capacitance–voltage measurements, we substantiate the role of polarization in inducing NDR effect in organic molecules.

1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/induce-negative-differential-resistance-organic-devices-through-ferroelectric-polymer01353nas a2200133 4500008004100000245009200041210006900133260000800202490000700210520083300217100002201050700001901072856012801091 2009 eng d00aOrganic memory and electrical bistability in a quinone –based charge transfer complex0 aOrganic memory and electrical bistability in a quinone based cha cAUG0 v973 a

We present an overview of the issues of organic memory devices and discuss the mechanisms involved in conductance switching. To make the memory elements addressable, we introduce nanostructures of a quinone-based charge-transfer complex. The devices based on charge-transfer complexes exhibit electrical bistability. Apart from characterizing complex formation, we study characteristics of memory devices based on the complexes. The mechanism of bistability has been discussed in terms of electroreduction of the quinone derivative with the formation of a percolating network of conducting molecules or channels across the device. Depending on the device architecture, a device may exhibit memoryswitching or threshold-switching phenomenon. The former system has displayed read-only and random-access memory applications.

1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/organic-memory-and-electrical-bistability-quinone-%E2%80%93based-charge-transfer-complex01258nas a2200157 4500008004100000245011600041210006900157260000800226300002700234490000700261520064500268100002200913700002000935700001900955856012600974 2010 eng d00aMn-doped nanocrystals in light-emitting diodes: energy-transfer to obtain electroluminescence from quantum dots0 aMndoped nanocrystals in lightemitting diodes energytransfer to o cSEP aArticle number: 1135020 v973 a

We fabricatelight-emitting diodes(LEDs) based on Mn-doped ZnSnanocrystals along with hole-transporting bis(3-methylphenyl)--diphenyl-benzidine (TPD). With Mn-doping, ZnSnanostructures exhibit a strong photoluminescence. The LEDs exhibit electroluminescence(EL) from Mn-doped ZnSquantum dots and TPD. In order to open up channels for energy-transfer from TPD to quantum dots and to achieve EL from only the nanoparticles, we grow core-shell nanoparticles with Mn-doped ZnS in the core and CdS as the shell layer. Excitons formed in TPD can now transfer their energy directly to the shell-layer to yield EL from only the nanoparticles.

1 aRath, Arup, Kumar1 aBhaumik, Saikat1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/mn-doped-nanocrystals-light-emitting-diodes-energy-transfer-obtain-electroluminescence01259nas a2200157 4500008004100000245012600041210006900167260000800236300002300244490000700267520063700274100001900911700002200930700001900952856013000971 2010 eng d00aNear-IR activity of hybrid solar cells: enhancement of efficiency by dissociating excitons generated in PbS nanoparticles0 aNearIR activity of hybrid solar cells enhancement of efficiency  cFEB aArticle no: 0735050 v963 a

Photovoltaic devices based on PbSnanoparticles remained inactive in the near-IR region due to a not-so-favorable energy band-diagram that does not allow dissociation of excitons generated in PbS. In this work, with the introduction of nanostructures in the PbS-based hybrid system, we show an enhancement of photovoltaic performance in both visible and near-IR regions. The addition of increases the power conversion efficiency from 0.006% to 0.12%. With the aid of energy band-diagram, we show that excitons generated in PbS even in the near-IR range can now become dissociated to yield photocurrent in the external circuit.

1 aGuchhait, Asim1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/near-ir-activity-hybrid-solar-cells-enhancement-efficiency-dissociating-excitons-generated01080nas a2200169 4500008004100000245011300041210006900154260000800223300001600231490000700247520043400254100002200688700002100710700001900731700002800750856013200778 2011 eng d00aSolution-processed heterojunction solar cells based on p-type PbS quantum dots and n-type Bi2S3 nanocrystals0 aSolutionprocessed heterojunction solar cells based on ptype PbS  cAUG a3712–37170 v233 a

Bi2S3 nanocrystals are employed as an n-type, non-toxic, inorganic, solution-processed semiconductor in thin film solar cells. The first solution processed-inorganic p-n junction based on p-type PbS QDs and n-type Bi2S3 nanocrystals with both phases contributing to photocarrier generation is demonstrated. The reported devices show a power conversion efficiency of 1.6% for 860 nm PbS QDs and over 1% for 1300 nm PbS QDs.

1 aRath, Arup, Kumar1 aBernechea, Maria1 aMartinez, Luis1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/solution-processed-heterojunction-solar-cells-based-p-type-pbs-quantum-dots-and-n-type-bi2s301721nas a2200157 4500008004100000245010700041210006900148260000800217300001400225490000700239520112500246100001901371700002201390700001901412856013201431 2011 eng d00aTo make polymer: quantum dot hybrid solar cells NIR-active by increasing diameter of PbS nanoparticles0 aTo make polymer quantum dot hybrid solar cells NIRactive by incr cOCT a651–6560 v953 a

We fabricate NIR-active solar cells based on PbS quantum dots and a conventional conjugated polymer. These devices act as solar cells under exclusively NIR wavelengths above 650 nm. Here PbS nanoparticles absorb photons in the NIR range that in turn generate excitons. We show that with an assistance from a strong electron-acceptor (TiO2), these excitons can be dissociated to electrons and holes to yield a photocurrent in the external circuit. We then aim to extend the spectral window of the solar cells to higher wavelength region by increasing the diameter of PbS nanoparticles to make the cells further NIR-active. We observe that the short-circuit current (JSC) shows a peak when the diameter of PbS nanoparticles increases. Here, the spectral window can be extended till conduction band-edge of PbS quantum dots falls below that of TiO2 nanostructures cutting off the electron-transfer pathway. The NIR-active photovoltaic solar cells yield a short-circuit current (JSC) of 1.0 mA/cm2, open-circuit voltage (VOC) of 0.42 V, and power conversion efficiency (η) of 0.16% and remain operative till 1200 nm.

1 aGuchhait, Asim1 aRath, Arup, Kumar1 aPal, Amlan, J. uhttps://library.ncl.res.in/content/make-polymer-quantum-dot-hybrid-solar-cells-nir-active-increasing-diameter-pbs-nanoparticles01647nas a2200193 4500008004100000245009600041210006900137260000800206300001400214490000600228520095200234100002201186700002101208700001901229700003001248700001901278700002801297856012801325 2012 eng d00aSolution-processed inorganic bulk nano-heterojunctions and their application to solar cells0 aSolutionprocessed inorganic bulk nanoheterojunctions and their a cJUL a529–5340 v63 a

In the last decade, solution-processed quantum dot/nanocrystal solar cells have emerged as a very promising technology for third-generation thin-film photovoltaics because of their low cost and high energy-harnessing potential. Quantum dot solar cell architectures developed to date have relied on the use of bulk-like thin films of colloidal quantum dots. Here, we introduce the bulk nano-heterojunction concept for inorganic solution-processed semiconductors. This platform can be readily implemented by mixing different semiconductor nanocrystals in solution and allows for the development of optoelectronic nanocomposite materials with tailored optoelectronic properties. We present bulk nano-heterojunction solar cells based on n-type Bi2S3 nanocrystals and p-type PbS quantum dots, which demonstrate a more than a threefold improvement in device performance compared to their bilayer analogue, as a result of suppressed recombination.

1 aRath, Arup, Kumar1 aBernechea, Maria1 aMartinez, Luis1 ade Arquer, Pelayo, Garcia1 aOsmond, Johann1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/solution-processed-inorganic-bulk-nano-heterojunctions-and-their-application-solar-cells01682nas a2200217 4500008004100000245007600041210006900117260000800186300002500194490000600219520094700225100002801172700002201200700003001222700002701252700001701279700001901296700001401315700002801329856010701357 2013 eng d00aHeterovalent cation substitutional doping for quantum dot homojunctions0 aHeterovalent cation substitutional doping for quantum dot homoju cDEC aArticle number: 29810 v43 a

Colloidal quantum dots have emerged as a material platform for low-cost high-performance optoelectronics. At the heart of optoelectronic devices lies the formation of a junction, which requires the intimate contact of n-type and p-type semiconductors. Doping in bulk semiconductors has been largely deployed for many decades, yet electronically active doping in quantum dots has remained a challenge and the demonstration of robust functional optoelectronic devices had thus far been elusive. Here we report an optoelectronic device, a quantum dot homojunction solar cell, based on heterovalent cation substitution. We used PbS quantum dots as a reference material, which is a p-type semiconductor, and we employed Bi-doping to transform it into an n-type semiconductor. We then combined the two layers into a homojunction device operating as a solar cell robustly under ambient air conditions with power conversion efficiency of 2.7%.

1 aStavrinadis, Alexandros1 aRath, Arup, Kumar1 ade Arquer, Pelayo, Garcia1 aDiedenhofen, Silke, L.1 aMagen, Cesar1 aMartinez, Luis1 aSo, David1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/heterovalent-cation-substitutional-doping-quantum-dot-homojunctions00618nas a2200169 4500008004100000245008700041210006900128260000800197300001400205490000700219100001800226700002000244700001900264700002200283700002800305856011500333 2013 eng d00aImprinted electrodes for enhanced light trapping in solution processed solar cells0 aImprinted electrodes for enhanced light trapping in solution pro cOCT a443–4480 v261 aMihi, Agustin1 aBeck, Fiona, J.1 aLasanta, Tania1 aRath, Arup, Kumar1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/imprinted-electrodes-enhanced-light-trapping-solution-processed-solar-cells01555nas a2200193 4500008004100000022001400041245010900055210006900164260012500233300001100358490000800369520074400377100002201121700001901143700002101162700002701183700002801210856012301238 2014 eng d a0003-695100aDetermination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy0 aDetermination of carrier lifetime and mobility in colloidal quan aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScFEB a0635040 v1043 a

Impedance Spectroscopy (IS) proves to be a powerful tool for the determination of carrier lifetime and majority carrier mobility in colloidal quantum dot films. We employ IS to determine the carrier lifetime in PbS quantum dot Schottky solar cells with Al and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of IS to characterize key-to-photovoltaics optoelectronic properties, carrier lifetime, and mobility, in a facile way. (C) 2014 AIP Publishing LLC.

1 aRath, Arup, Kumar1 aLasanta, Tania1 aBernechea, Maria1 aDiedenhofen, Silke, L.1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/determination-carrier-lifetime-and-mobility-colloidal-quantum-dot-films-impedance-001330nas a2200217 4500008004100000022001400041245012800055210006900183260007700252300001000329490000700339520046300346100002200809700003000831700002800861700001900889700002100908700002700929700002800956856012800984 2014 eng d a0935-964800aRemote trap passivation in colloidal quantum dot bulk nano-heterojunctions and its effect in solution-processed solar cells0 aRemote trap passivation in colloidal quantum dot bulk nanohetero aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUL a4741+0 v263 a

More-efficient charge collection and suppressed trap recombination in colloidal quantum dot (CQD) solar cells is achieved by means of a bulk nano-heterojunction (BNH) structure, in which p-type and n-type materials are blended on the nanometer scale. The improved performance of the BNH devices, compared with that of bilayer devices, is displayed in higher photocurrents and higher open-circuit voltages (resulting from a trap passivation mechanism).

1 aRath, Arup, Kumar1 ade Arquer, Pelayo, Garcia1 aStavrinadis, Alexandros1 aLasanta, Tania1 aBernechea, Maria1 aDiedenhofen, Silke, L.1 aKonstantatos, Gerasimos uhttps://library.ncl.res.in/content/remote-trap-passivation-colloidal-quantum-dot-bulk-nano-heterojunctions-and-its-effect-002095nas a2200145 4500008004100000245010100041210006900142260000800211300001200219490000800231520153400239100002901773700002201802856012501824 2018 eng d00a Photo-induced surface modification to improve the performance of lead sulfide quantum dot solar0 aPhotoinduced surface modification to improve the performance of  cJUL a120-1250 v5223 aThe solution-processed quantum dot (QD) solar cell technology has seen significant advancements in recent past to emerge as a potential contender for the next generation photovoltaic technology. In the development of high performance QD solar cell, the surface ligand chemistry has played the important role in controlling the doping type and doping density of QD solids. For instance, lead sulfide (PbS) QDs which is at the forefront of QD solar cell technology, can be made n-type or p-type respectively by using iodine or thiol as the surfactant. The advancements in surface ligand chemistry enable the formation of p-n homojunction of PbS QDs layers to attain high solar cell performances. It is shown here, however, that poor Fermi level alignment of thiol passivated p-type PbS QD hole transport layer with the n-type PbS QD light absorbing layer has rendered the photovoltaic devices from realizing their full potential. Here we develop a control surface oxidation technique using facile ultraviolet ozone treatment to increase the p-doping density in a controlled fashion for the thiol passivated PbS QD layer. This subtle surface modification tunes the Fermi energy level of the hole transport layer to deeper values to facilitate the carrier extraction and voltage generation in photovoltaic devices. In photovoltaic devices, the ultraviolet ozone treatment resulted in the average gain of 18% in the power conversion efficiency with the highest recorded efficiency of 8.98%. (C) 2018 Elsevier Inc. All rights reserved.1 aTulsani, Srikanth, Reddy1 aRath, Arup, Kumar uhttps://library.ncl.res.in/content/photo-induced-surface-modification-improve-performance-lead-sulfide-quantum-dot-solar02092nas a2200253 4500008004100000245007200041210006900113260000800182300001400190490000600204520132000210653002101530653001401551653002401565653001601589653001701605100001801622700001701640700001901657700001801676700002201694700001901716856010301735 2022 eng d00aCdSe quantum dot-based nanocomposites for ultralow-power memristors0 aCdSe quantum dotbased nanocomposites for ultralowpower memristor cJUN a8502-85100 v53 a

The explosion in digital communication with the huge amount of data and the internet of things (IoT) led to the increasing demand for data storage technology with faster operation speed, high-density stacking, nonvolatility, and low power consumption for saving energy. Metal chalcogenide-based quantum dots (QDs) show excellent nonvolatile resistive memory behavior owing to their tunable electronic states and control in trap states by passivating the surface with different ligands. Here, we synthesized high-quality colloidal monodispersed CdSe QDs by the hot injection method. The CdSe QDs were blended with an organic polymer, poly(4-vinylpyridine) (PVP), to fabricate an Al\textbackslashCdSe-PVP\textbackslashAl device. Our device shows excellent bipolar nonvolatile resistive random access memory (RRAM) switching behavior with a high current ON/OFF ratio (I-ON/OFF) of 6.1 x 10(4), and it consumes ultralow power. The charge trapping and detrapping in the potential well formed by the CdSe QD and PVP combination result in resistive switching. This CdSe-PVP-based resistive random access memory (RRAM) device with a high I-ON/OFF, ultrafast switching speed, high endurance, low operating voltage, and long retention period can be used as a high-performance and ultralow-power memristive device.

10amemory switching10amemristor10ametal chalcogenides10anonvolatile10aquantum dots1 aBera, Jayanta1 aBetal, Atanu1 aSharma, Ashish1 aShankar, Uday1 aRath, Arup, Kumar1 aSahu, Satyajit uhttps://library.ncl.res.in/content/cdse-quantum-dot-based-nanocomposites-ultralow-power-memristors02185nas a2200193 4500008004100000022001400041245012500055210006900180260000800249300001100257490000800268520149100276100001801767700001701785700001901802700002201821700001901843856012901862 2022 eng d a0003-695100aColloidal MoS2 quantum dots for high-performance low power resistive memory devices with excellent temperature stability0 aColloidal MoS2 quantum dots for highperformance low power resist cJUN a2535020 v1203 a

Conventional memory technologies are facing enormous problems with downscaling, and are hence unable to fulfill the requirement of big data storage generated by a huge explosion of digital information. A resistive random access memory device (RRAM) is one of the most emerging technologies for next-generation computing data storage owing to its high-density stacking, ultrafast switching speed, high non-volatility, multilevel data storage, low power consumption, and simple device structure. In this work, colloidal MoS2 quantum dots (QDs) embedded in an insulating matrix of poly-(4vinylpyridine) (PVP) were used as an active layer to fabricate a RRAM device. The MoS2 QDs-PVP based RRAM device reveals an excellent nonvolatile resistive switching (RS) behavior with a maximum current on-off ratio (I-ON/I-OFF) of 10(5). High endurance, long retention time, and successive ``write-read-erase-read'' cycles indicate high-performance RRAM characteristics. The ultimate power consumption by this RRAM device is considerably low for energy saving. In addition, the MoS2 QDs-PVP based device shows RS behavior even at 130 degrees C. High I-ON/I-OFF, low operating power, high endurance, long retention time, and excellent stability with temperatures reveal that the MoS2 QDs-PVP based device can be a promising candidate for high-performance low power RRAM devices that can be operated at relatively higher temperatures. Published under an exclusive license by AIP Publishing.

1 aBera, Jayanta1 aBetal, Atanu1 aSharma, Ashish1 aRath, Arup, Kumar1 aSahu, Satyajit uhttps://library.ncl.res.in/content/colloidal-mos2-quantum-dots-high-performance-low-power-resistive-memory-devices-excellent12840nas a2200181 45000080041000002450159000412100069002002600008002693000016002774900006002935201219600299100001712495700001812512700002312530700002212553700003112575856005212606 2024 eng d00aLead-free low-dimensional tetraalkylammonium manganese- and copper-based hybrid organic–inorganic perovskites for visual fluorometric Pb2+ ion detection0 aLeadfree lowdimensional tetraalkylammonium manganese and copperb cJUL a1533–15450 v23 a

For the first time, we have synthesized lead (Pb)-free manganese (Mn)- and copper (Cu)-based hybrid organic–inorganic perovskite (HOIP) compounds, compound 1, (TEA)2MnBr4, compound 2, (TBA)2MnBr4, compound 3, (TEA)2CuBr4, and compound 4, (TBA)CuBr2 (where TEA is tetraethylammonium and TBA is tetrabutylammonium), under ambient conditions via mechanochemical synthesis methodology using a Kakuhunter-made planetary mixer. The compounds are characterized as 2D except for (TBA)CuBr2, which has crystallized in the 0D lattice. The synthesized compounds are phase pure and show a stable solid-state emission at room temperature. The Mn-based perovskite compound 1 showed excellent environmental photostability for over a month and reasonable stability under a relative humidity of 70–80%. The nanoparticle (NP) dispersions of compounds 1 and 2 were used further for fluorescence titration studies using various heavy metal cations, including transition metals and lanthanides (e.g., Y3+, Nb3+, Co2+, Ni2+, Ag+, Zn2+, Cd2+, Pb2+, Gd3+, and Dy3+), where they showed good fluorescence switching by the Pb2+ ion. Compound 1 demonstrated excellent fluorescence switching performance with Pb2+ titration with a Pb2+ detection limit of 2.43 × 10–8 M and hence can be used to fabricate a Pb2+ calorimetric sensor. A preliminary visual thin film-based sensor using NPs of compound 1 was fabricated to test the change in emission from blue to green in correlation with the results obtained in the NP solution during Pb2+ ion sensing. A fascinating in situ ion-exchange-based mechanism for the sensitivity of NPs of compound 1 is confirmed. This study reveals the ability of Pb-free Mn-based HOIPs to detect an oxidizing metal cation, Pb2+, efficiently and quantitatively.

1 aKour, Prachi1 aSahu, Pragati1 aDambhare, Neha, V.1 aRath, Arup, Kumar1 aMukherjee, Shatabdi, Porel uhttps://pubs.acs.org/doi/10.1021/acsaom.4c0018200793nas a2200217 4500008004100000245010400041210006900145260000900214300001600223490000600239653002700245653003200272100002100304700002300325700002000348700001600368700002200384700001900406700002000425856013000445 2024 eng d00aMagnetic chemiresistive Fe-doped In2O3 nanocubes to Tunably detect NO2 at ppm to ppb concentrations0 aMagnetic chemiresistive Fedoped In2O3 nanocubes to Tunably detec cJUN  a14331-143430 v710aGAS-SENSING PROPERTIES10aMETAL-OXIDE NANOSTRUCTURES1 aRudra, Pratyasha1 aDambhare, Neha, V.1 aSrihari, Velaga1 aDas, Sagnik1 aRath, Arup, Kumar1 aSaha, Debdulal1 aMondal, Swastik uhttps://library.ncl.res.in/content/magnetic-chemiresistive-fe-doped-in2o3-nanocubes-tunably-detect-no2-ppm-ppb-concentrations01132nas a2200337 4500008004100000022001400041245014100055210006900196260000800265490000700273653002400280653002800304653002800332100002400360700001900384700002200403700002100425700001900446700002200465700001800487700001800505700001800523700000500541700002200546700001600568700001700584700002500601700001700626700002500643856012600668 2024 eng d a1616-301X00aTransient Electro-Graphitization of MOFs Affecting the Crystallization of Ruthenium Nanoclusters for Highly Efficient Hydrogen Evolution0 aTransient ElectroGraphitization of MOFs Affecting the Crystalliz cAUG0 v3410aamorphous ruthenium10acrystallization control10agraphitic nanostructure1 aKarim, Golam, Masud1 aPatra, Amalika1 aDeb, Sujit, Kumar1 aUpadhya, Hemanta1 aDas, Snehasish1 aMukherjee, Priyam1 aAhmad, Waleed1 aBarman, Narad1 aThapa, Ranjit1 a1 aRath, Arup, Kumar1 aDas, Jaysri1 aManna, Uttam1 aUrkude, Rajashri, R.1 aOh, Youngtak1 aMaiti, Uday, Narayan uhttps://library.ncl.res.in/content/transient-electro-graphitization-mofs-affecting-crystallization-ruthenium-nanoclusters01963nas a2200217 4500008004100000022001400041245018500055210006900240260000800309300001400317490000700331520112300338100002301461700002001484700001901504700002901523700001801552700002501570700002201595856012801617 2025 eng d a2380-819500aFermi-level equilibrium-driven trap filling in multibandgap PbS quantum dot solids enabling record voltage generation and improved carrier transport in high-performance solar cells0 aFermilevel equilibriumdriven trap filling in multibandgap PbS qu cDEC a6336-63460 v103 a

To leverage the unique optical properties of quantum dots (QDs) in solar cells, it is crucial to address electronic traps from unsaturated surface states of high surface area QDs. Despite advancements in surface passivation, even the best-coupled QD solids exhibit significant sub-bandgap trap states. This study introduces engineered multibandgap PbS QD solids that achieve passivation of deep traps below the conduction band through electron migration from dopant QDs. Our findings indicate that electron flow, driven by Fermi energy balancing in blend films, fills deep trap states, reducing trap density by half and shifting trap energy positions closer to the conduction band. During electrical transport, trap filling minimizes trapping and detrapping events, enhancing overall carrier mobility, despite higher-bandgap dopant QDs not contributing to carrier transport due to their unfavorable energy positions. Improved trap passivation in coupled QD solids leads to a record V oc of 725 +/- 10 meV for the 1.33 eV excitonic peak of QDs and a power conversion efficiency exceeding 14% in solar cells.

1 aDambhare, Neha, V.1 aBiswas, Arindam1 aSharma, Anjali1 aShinde, Dipak, Dattatray1 aMitra, Anurag1 aGirade, Vrushali, S.1 aRath, Arup, Kumar uhttps://library.ncl.res.in/content/fermi-level-equilibrium-driven-trap-filling-multibandgap-pbs-quantum-dot-solids-enabling