02679nas a2200241 4500008004100000022001400041245009400055210006900149260000900218300001600227490000700243520189100250653002202141653001902163653001602182653001602198653002402214653001602238100002102254700001902275700001902294856012402313 2020 eng d a1944-824400aSolution-phase hybrid passivation for efficient infrared-band gap quantum dot solar cells0 aSolutionphase hybrid passivation for efficient infraredband gap  cNOV  a49840-498480 v123 a

The broad tunability of the energy band gap through size control makes colloidal quantum dots (QDs) promising for the development of photovoltaic devices. Large-size lead sulfide (PbS) QDs, exhibiting a narrow energy band gap, are particularly interesting as they can be used to augment perovskite and c-Si solar cells due to their complementary NIR absorption. However, their complex surface chemistry makes them difficult to process for the development of solar cells. The shape of the QDs transformed from octahedron to cuboctahedron as their size increases, a phenomenon guided by surface energy minimization. As a result, the surface properties change drastically for large-size QDs, which exhibit nonpolar (200) facets and polar (111) facets, as opposed to only (111) facets in small-size QDs. Recent advancements in solution-phase surface passivation strategies, used for the development of high-performance solar cells using the small size and wide band gap QDs, failed to translate a similar enhancement in the case of large-size and narrow band gap QDs. Here, we report a hybrid passivation strategy for large-size and narrow band gap QDs to passivate both (111) and (200) facets, respectively, using inorganic lead triiodide (PbI3-) and organic 3-chloro-1-propanethiol (CPT). By employing charge balance calculation, we identified the desired narrow band gap for QDs to complement the perovskite and c-Si absorption. The distinct choice of the organic ligand CPT enhances the colloidal stability of QDs in the solution phase and improves surface passivation to stop QD fusion in solid films. Photophysical properties show narrower excitonic and emission peaks and a reduction in the Stokes shift. Hybrid passivation leads to a 94% increase in the power conversion efficiency of solar cells and a 74% increase in the external quantum efficiency at the excitonic peak.

10ainfrared band gap10apolydispersity10aquantum dot10asolar cells10asurface passivation10atrap states1 aMahajan, Chandan1 aSharma, Ashish1 aRath, Arup, K. uhttp://library.ncl.res.in/content/solution-phase-hybrid-passivation-efficient-infrared-band-gap-quantum-dot-solar-cells02630nas a2200289 4500008004100000245014600041210006900187260000800256300001400264490000600278520164500284653001801929653001801947653002701965653001701992653002402009653003402033653000802067100001702075700001902092700001802111700002302129700001902152700001902171700001902190856013102209 2024 eng d00aScanning tunneling microscopy investigation of synaptic behavior in AgInS2 quantum dots: effect of ion transport in neuromorphic applications0 aScanning tunneling microscopy investigation of synaptic behavior cMAR a7226-72360 v73 a

Scanning tunneling microscopy (STM) is a powerful technique for investigating the nanoscale properties of functional materials. Additionally, scanning tunneling spectroscopy (STS) facilitates the determination of the local density of states (LDOS) within the material. In this study, we present an exploration of the resistive switching (RS) properties and neuromorphic computing capabilities of individual AgInS2 quantum dots, utilizing STM and STS techniques. By examining the material's bandgap and its temperature dependence, we uncover a nonlinear variation below the Debye temperature and a linear trend at higher temperatures. Moreover, STS measurements demonstrate changes in the conducting states induced by localized pulses, further confirming the unique characteristics of the quantum dots. The experimental devices constructed by using these quantum dots effectively replicate the RS properties observed at the nanoscale. To assess the neuromorphic application of the devices, pulse transient measurements simulating the learning and forgetting processes were conducted. The gradual set and reset processes successfully mimic the information retention and erasure capabilities essential for neuromorphic computing. Notably, the resistive switching mechanism in these devices is attributed to localized ionic transport, which highlights the significant involvement of ionic species in the observed RS behavior. The outcomes of this study contribute to the fundamental understanding of RS properties in single AgInS2 quantum dots and offer valuable insights into their potential applications in neuromorphic computing.

10acorona poling10aIon transport10aneuromorphic computing10aquantum dots10aresistive switching10aScanning tunneling microscopy10aSTS1 aBetal, Atanu1 aChetia, Anupam1 aBera, Jayanta1 aSaikia, Dibyajyoti1 aSharma, Ashish1 aRath, Arup, K.1 aSahu, Satyajit uhttp://library.ncl.res.in/content/scanning-tunneling-microscopy-investigation-synaptic-behavior-agins2-quantum-dots-effect-ion02396nas a2200289 4500008004100000245009400041210006900135260000900204300001400213490000600227520146100233653002401694653001701718653002301735653002601758653001801784653001601802100002001818700001801838700001901856700002901875700001901904700001901923700002101942700001901963856012401982 2024 eng d00aSolution-phase ligand engineering for all-quantum-dot near-infrared light-emitting diodes0 aSolutionphase ligand engineering for allquantumdot nearinfrared  cAPR  a9126-91350 v73 a

Strong emission over a wide near-infrared (NIR) region makes lead sulfide quantum dots (QDs) a preferred material in building NIR light-emitting diodes (NIR-LEDs) for numerous applications. Narrow-bandgap emitter QDs blended in the matrix of high-band gap QDs offer a simple yet powerful architectural platform for building high-performance NIR-LEDs. So far, the all-QD-based blend architecture has been realized using a poorly controlled solid-state ligand exchange approach. Advanced solution-phase ligand exchange, which offers greater control over surface passivation, is yet to be realized in all-QD LED device construction. We observe that the solution-phase ligand exchange from the optimized lead halide and thiol ligand combination, used in high-performing QD solar cell construction, is inefficient in realizing efficient all-QD LEDs, which could have restricted the adoption of the solution-phase ligand exchange thus far. Here, we introduce an innovative dual-ligand strategy to build all-QD-based NIR-LEDs using an advanced solution-phase ligand exchange approach. Through ligand engineering of matrix QDs, we managed to improve photoluminescence quantum yield (40%), reduce trap density (10(14) cm(-3)), and prolong carrier lifetime (832 ns). The LED devices benefit from improved electronic properties and balanced carrier injection to yield 6% EQE and 7.7% PCE, which are six times higher than those of state-of-the-art ligands.

10aelectroluminescence10alead sulfide10aligand passivation10alight-emitting diodes10anear-infrared10aquantumdots1 aBiswas, Arindam1 aMitra, Anurag1 aSharma, Ashish1 aShinde, Dipak, Dattatray1 aDambhare, Neha1 aSharma, Anjali1 aMahajan, Chandan1 aRath, Arup, K. uhttp://library.ncl.res.in/content/solution-phase-ligand-engineering-all-quantum-dot-near-infrared-light-emitting-diodes02378nas a2200277 4500008004100000022001400041245014500055210006900200260000900269300001600278490000700294520143500301653002101736653001701757653002301774653001701797653001501814100002901829700001901858700002301877700002101900700002001921700001801941700001901959856012201978 2024 eng d a1944-824400aSynthesis and processing strategy for high-bandgap PbS quantum dots: a promising candidate for harvesting high-energy photons in solar cells0 aSynthesis and processing strategy for highbandgap PbS quantum do cAUG  a42522-425330 v163 a

The wide tunability of the energy bandgap of colloidal lead sulfide (PbS) quantum dots (QDs) has uniquely positioned them for the development of single junction and tandem solar cells. While there have been substantial advancements in moderate and narrow bandgap PbS QDs-ideal for single junction solar cells and the bottom cell in tandem solar cells, respectively; progress has been limited in high-bandgap PbS QDs that are ideally suited for the formation of the top cell in tandem solar cells. The development of appropriate high bandgap PbS QDs would be a major advancement toward realizing efficient all-QD tandem solar cells utilizing different sizes of PbS QDs. Here, we report a comprehensive approach encompassing synthetic strategy, ligand engineering, and hole transport layer (HTL) modification to implement high-bandgap PbS QDs into solar cell devices. We achieved a greater degree of size homogeneity in high-bandgap PbS QDs through the use of a growth retarding agent and a partial passivation strategy. By adjusting the ligand polarity, we successfully grow HTL over the QD film to fabricate solar cells. With the aid of an interface modifying layer, we incorporated an organic HTL for the realization of high-performance solar cells. These solar cells exhibited an impressive open-circuit voltage of 0.824 V and a power conversion efficiency of 10.7%, marking a 360% improvement over previous results.

10acharge transport10alead sulfide10aligand passivation10aquantum dots10asolar cell1 aShinde, Dipak, Dattatray1 aSharma, Anjali1 aDambhare, Neha, V.1 aMahajan, Chandan1 aBiswas, Arindam1 aMitra, Anurag1 aRath, Arup, K. uhttp://library.ncl.res.in/content/synthesis-and-processing-strategy-high-bandgap-pbs-quantum-dots-promising-candidate03162nas a2200301 4500008004100000022001400041245017900055210006900234260000800303300001400311490000700325520211500332653001702447653002302464653001802487653001702505653001502522653002102537100001902558700002902577700002102606700002302627700002002650700001802670700002502688700001902713856012802732 2025 eng d a1944-824400aSynergistic improvement of narrow bandgap PbS quantum dot solar cells through surface ligand engineering, near-infrared spectral matching, and enhanced electrode transparency0 aSynergistic improvement of narrow bandgap PbS quantum dot solar  cJAN a6614-66250 v173 a

The tunability of the energy bandgap in the near-infrared (NIR) range uniquely positions colloidal lead sulfide (PbS) quantum dots (QDs) as a versatile material to enhance the performance of existing perovskite and silicon solar cells in tandem architectures. The desired narrow bandgap (NBG) PbS QDs exhibit polar (111) and nonpolar (100) terminal facets, making effective surface passivation through ligand engineering highly challenging. Despite recent breakthroughs in surface ligand engineering, NBG PbS QDs suffer from uncontrolled agglomeration in solid films, leading to increased energy disorder and trap formation. The limited NIR transparency of commonly used indium-doped tin oxide (ITO) electrodes and inadequate NIR radiation from commercially available solar simulators further compromise the true performance of NBG PbS QDs in solar cells. Here, we employ a hybrid ligand strategy based on inorganic cadmium halide and organic thiol molecules, leading to the partial substitution of surface Pb atoms with Cd heteroatoms. This hybrid ligand strategy substantially reduces undesired QD fusion in solid films, improving the photophysical and electronic properties. By modulating the thickness of the ITO layer and managing refraction loss through a ZnO layer coating, we improved NIR transparency to above 80%. We combine an NIR light source with a solar simulator to achieve near-ideal spectral matching for a broader range with standard AM1.5G illumination. Enhancements in surface passivation of QDs, improvements in NIR transparency of electrodes, and a spectral matched light source setup help us achieve solar cell power conversion efficiencies of 12.4%, 4.48%, and 1.37% under AM 1.5G, perovskite filter, and silicon filter illuminations, respectively. A record open-circuit voltage (V oc) of 0.54 V and short-circuit current density (J sc) of 38.5 mA/cm2 are achieved under AM 1.5G illumination. We attribute these advancements in photovoltaic parameters to the reduction in Urbach tail states and intermediate trap density originating from superior surface passivation of QDs.

10alead sulfide10aligand passivation10anear-infrared10aquantum dots10asolar cell10atandem solarcell1 aSharma, Anjali1 aShinde, Dipak, Dattatray1 aMahajan, Chandan1 aDambhare, Neha, V.1 aBiswas, Arindam1 aMitra, Anurag1 aGirade, Vrushali, S.1 aRath, Arup, K. uhttp://library.ncl.res.in/content/synergistic-improvement-narrow-bandgap-pbs-quantum-dot-solar-cells-through-surface-ligand