02162nas a2200217 4500008004100000022001400041245015500055210006900210260000800279300001600287490000700303520136200310100002301672700002001695700001901715700002901734700002101763700001801784700001901802856012301821 2023 eng d a2050-748800aHigh open-circuit voltage in lead sulfide quantum dot solar cells via solution-phase ligand exchange with low electron affinity cadmium halides0 aHigh opencircuit voltage in lead sulfide quantum dot solar cells cAUG a17282-172910 v113 a

The deployment of colloidal quantum dots (QDs) in building high-performance solar cells and other optoelectronic applications relies on the passivation of unsaturated surface atoms through ligand engineering to attain a trap-free energy bandgap and strong QD coupling while maintaining the quantum confinement effect. Despite major advancements in surface passivation strategies, the open circuit voltage (V-oc) of lead sulfide (PbS) QD solar cells is limited by undesirable sub-bandgap states and high-bandtail states. The most advanced solution-phase ligand exchange strategy for PbS QDs depends on lead halide ligands, which improved the photocurrent and fill factor in QD solar cells significantly, but only an incremental change in V-oc is observed. Here we showcase a solution-phase hybrid ligand passivation strategy for PbS QDs using shallow electron affinity cadmium halide and thiol ligands. The cadmium halide ligand treatment results in the sub-monolayer substitution of surface Pb atoms by Cd atoms. The photophysical properties of QDs improve significantly to show intense band edge emission, diminished trap emission and reduced Urbach tail states. The photovoltaic devices built using cadmium halide-treated QDs show low reverse saturation current, which helps to attain a record 0.7 V V-oc (for a 1.28 eV bandgap) and 12.3% PCE.

1 aDambhare, Neha, V.1 aBiswas, Arindam1 aSharma, Anjali1 aShinde, Dipak, Dattatray1 aMahajan, Chandan1 aMitra, Anurag1 aRath, Arup, K. uhttp://library.ncl.res.in/content/high-open-circuit-voltage-lead-sulfide-quantum-dot-solar-cells-solution-phase-ligand02122nas a2200265 4500008004100000022001400041245007200055210006900127260000800196490000700204520129400211653002501505653001801530653001801548653001701566653001601583653002401599100002101623700002301644700002001667700001901687700002901706700001901735856010201754 2023 eng d a2194-428800aMulti-bandgap quantum dots ensemble for near-infrared photovoltaics0 aMultibandgap quantum dots ensemble for nearinfrared photovoltaic cJUN0 v113 a

Narrow bandgap quantum dots (QDs) are an important class of materials for near-infrared (NIR) optoelectronic devices owing to their size-tunable bandgap and chemical root processing. In photovoltaic applications, NIR QDs could be particularly useful to complement the sub-bandgap transmission loss of NIR solar radiation from perovskite and c-Si solar cells. However, insufficient carrier extraction thickness associated with the narrow NIR excitonic bandwidth of QDs limits the conversion efficacy of the broad NIR solar spectrum. Here, we utilize a multi-bandgap QD ensemble which widens the NIR absorption bandwidth to mimic the broad solar spectrum. A solution-phase ligand passivation strategy is used to control doping properties and energy level alignment of multi-bandgap QDs. We successfully developed bulk-heterojunction solar cells using the multi-bandgap QD ensemble, which yields higher carrier extraction thickness and broader NIR absorption. The gain from NIR absorption and carrier transport resulted in higher short-circuit current generation and power conversion efficiency (PCE) in solar cell devices. The champion device shows 8.73% PCE under 1.5 AM solar illumination and 7.44% and 5.05% PCE for the NIR photons transmitted from perovskite and c-Si layers.

10abulk-heterojunctions10amulti-bandgap10anear-infrared10aquantum dots10asolar cells10asurface passivation1 aMahajan, Chandan1 aDambhare, Neha, V.1 aBiswas, Arindam1 aSharma, Anjali1 aShinde, Dipak, Dattatray1 aRath, Arup, K. uhttp://library.ncl.res.in/content/multi-bandgap-quantum-dots-ensemble-near-infrared-photovoltaics02396nas 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-candidate