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Lead Free, Aqua Stable A3Bi2I9 Perovskites: Crystal Growth and Blue Emitting Quantum dots [A = CH3NH3+, Cs+ and (Rb0.05Cs2.95)+]
摘要： Despite a great success in the rise in the power conversion efficiency of lead-halide perovskite solar cells, the toxicity of lead and the unstable nature of materials are the major concerns for their wide range of implementation at the industrial level. Herein, we have developed large size single crystals (SCs) in HI solution using temperature lowering method and nanocrystals (NCs) in ethanol (EtOH) and toluene (TOL) solvents of A3Bi2I9 perovskites [where, A = CH3NH3+ (MA)+, Cs+ and (Rb0.05Cs2.95)+]. The stability of A3Bi2I9 perovskite is investigated by immersing the SCs for 24 h and pellet for 12 h into water. Moreover, the A3Bi2I9 perovskite NCs displays a promising photoluminescence quantum yield of 17.63% and a longer lifetime of 8.20 ns.
关键词： Pb-Free Perovskites,Crystal Growth,High PLQY,Water Stability,Phase Transition,Nanocrystals,Low Bandgap
更新于2025-09-23 15:19:57
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Tin-lead Alloying for Efficient and Stable All-inorganic Perovskite Solar Cells
摘要： Cesium containing all-inorganic perovskites have received considerable interest in photovoltaics research because of their potential for improved stability compared to their organic-inorganic hybrid counterparts. However, the inorganic perovskites studied thus far still suffer from lower power conversion efficiency and long-term instability, due to an unfavorable bandgap and either phase instability or air-sensitivity. Herein, A strategy to mitigate these concerns is investigated by alloying tin and lead on the B site to form tin-lead alloyed low-bandgap (~1.34 eV) inorganic CsSn0.3Pb0.7I3 perovskites. Solar cells made using this material in an inverted full-structured architecture with a PEDOT:PSS hole transport materials (HTM) attain power conversion efficiency (PCE) up to 9.41% (stabilized PCE 7.23%). Furthermore, a simple HTM-free device without PEDOT:PSS layer is demonstrated more stable than the full-structured device and exhibits a PCE of 7.60% (stabilized PCE 7.31%) – the highest efficiency to date for an inorganic perovskite with a bandgap below 1.40 eV. This simplified device structure shows good reproducibility and stability. This work provides a possible route for fabricating low-cost, high stability devices with competitive efficiencies.
关键词： tin-lead alloying,solar cells,all-inorganic perovskite,low-bandgap,stability
更新于2025-09-23 15:19:57
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Improving Low Bandgap Tin Lead Perovskite Solar Cells via Contact Engineering and Gas Quench Processing
摘要： Low bandgap Sn/Pb ABX3 perovskites have reached photovoltaic power conversion efficiencies >20%, but usually have poor stability due to the common use of acidic PEDOT:PSS hole transport layers and A-site cation compositions containing methylammonium (MA). Here, we develop a process to enable high quality MA-free Sn/Pb perovskite films grown using a gas quenching process instead of the conventional antisolvents, which provides improved control of the film growth and eliminates wrinkling. Using this method in a device structure with PTAA instead of PEDOT:PSS as the hole transport layer, devices can reach efficiencies up to 20%mppt at 0.06 cm2 and up to 17.5%mppt at 1 cm2 active area. With these improvements, the devices are characterized for thermal stability and show 80% of the initial power remaining after 4000 hours at 85°C.
关键词： Low bandgap,Tin Lead Perovskite,Gas Quench Processing,Contact Engineering,Solar Cells
更新于2025-09-23 15:19:57
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Broadband polymer photodetectors with a good trade-off between broad response and high detectivity by using combined electron-deficient moieties
摘要： High-performance broadband photodetectors based on low-bandgap conjugated polymers are scarce due to a trade-off between the photoresponse range and device performance. In this work, the polymers with structural features responsible for both broad response and high detectivity are realized by using the combined electron deficient moieties at the molecular level. Based on the electron-deficient diketopyrrolopyrrole (DPP) and benzothiadiazole (BT), the combined units of DPP-DPP and DPP-BT-DPP are deemed more electron deficient and were successfully incorporated into the corresponding polymers. The arrangement of electron deficient moieties in the polymer mainchain were found to be able to greatly affect the absorption profile, energy level, molecular stacking, and blend film morphology. Consequently, the photodetector based on the polymer with DPP-BT-DPP acceptor exhibited the D* value of over 1012 Jones in the spectral region of 320–930 nm under -0.1 V bias.
关键词： low-bandgap conjugated polymers,electron deficient moieties,high detectivity,DPP,broadband photodetectors,BT
更新于2025-09-16 10:30:52
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Dual-source Co-evaporation of Low-bandgap FA <sub/>1-x</sub> Cs <sub/>x</sub> Sn <sub/>1-y</sub> Pb <sub/>y</sub> I <sub/>3</sub> Perovskites for Photovoltaics
摘要： Perovskite halides are well-suited to monolithic multijunction photovoltaics, promising low cost solar-to-electrical power conversion. Critical to all-perovskite multijunction fabrication is the deposition of a low-bandgap absorber without damaging other device layers. Vapour deposition is thus an attractive method, obviating the need for optically lossy protective interlayers, but is challenging for multi-component perovskites. Here, we demonstrate a method to dual-source co-evaporate low-bandgap perovskite films and devices. We used mixtures formed by melting of metal halides as a single-crucible source of Cs, Pb, and Sn cations. Surprisingly, when this melt was co-evaporated with formamidinium iodide (FAI), uniform and dense perovskite films in the family FA1-xCsxSn1-yPbyI3 were formed. Inclusion of SnF2 in the melt helped to regulate the perovskite’s optoelectronic quality leading to a steady-state power conversion efficiency of ~10% in a solar cell. This represents a new processing paradigm for evaporated perovskite alloys, which is an important step towards all-perovskite multijunction photovoltaics.
关键词： power conversion efficiency,perovskite halides,low-bandgap absorber,SnF2,vapour deposition,formamidinium iodide,multijunction photovoltaics
更新于2025-09-16 10:30:52
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Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA <sub/>0.8</sub> MA <sub/>0.2</sub> Sn <sub/>0.5</sub> Pb <sub/>0.5</sub> I <sub/>3</sub> ) for All‐Perovskite Tandem Solar Cells
摘要： All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (EG ≈1.6–1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (EG < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum-assisted growth control (VAGC) of solution-processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well-established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge-carrier lifetime. The improved optoelectronic characteristics enable high-performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four-terminal all-perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active-area solar cells up to 1 cm2.
关键词： vacuum-assisted growth control,all-perovskite tandem solar cells,solar cells,large grain,low-bandgap perovskites
更新于2025-09-12 10:27:22
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Low-Bandgap Polymer-based Infrared-to-Visible Up-Conversion Organic Light-Emitting Diodes with Infrared Sensitivity up to 1.1μm
摘要： All-organic infrared (IR)-to-visible up-conversion organic light-emitting diodes (OLEDs) with an IR sensitivity up to 1,100nm were fabricated using a low bandgap polymer as the organic IR sensitizing layer. A novel low bandgap (1 eV) polymer, poly 4-(4,8-bis(5-(2-butyloctyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophen-2-yl)-6,7-diethyl-[1,2,5] thiadiazolo[3,4-g]quinoxaline (PBDTT-BTQ), with a strong photo-response in near-IR wavelengths of 700-1,100nm was first synthesized using a thiadiazolo[3,4]quinoxaline (BTQ) and a thiophene-substituted benzo[1,2-b:4,5-b2-bdithiophene (BDTT) as the electron-withdrawing and donating building blocks, respectively. The near-IR photodetector was then fabricated for evaluating a PBDTT-BTQ as the IR sensitizing layer. The PBDTT-BTQ IR photodetector showed detectivity greater than 1011 Jones in multi-spectral region (300-1,100nm) and the maximum detectivity of 3.1× 1011 Jones at the wavelength of 1,000nm due to significantly reducing dark current (8.8 × 10-6 mA/cm2 at -1 V). Finally, the all-organic IR up-conversion OLED with a PBDTT-BTQ IR sensitizer successfully converted invisible near-IR light of 700nm-1,100nm directly to visible green light with a peak emission wavelength of 520nm. This is the first report of all-organic IR-to-visible up-conversion OLED with near-IR sensitivity up to 1,100nm.
关键词： Organic Light Emitting Diode,Low Bandgap Polymer,Up-Conversion,Near-Infrared
更新于2025-09-12 10:27:22
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Diketopyrrolopyrrole/perylene-diimide and thiophene based D-π-A low bandgap polymer sensitizers for application in dye sensitized solar cells
摘要： In this study, diketopyrrolopyrrole-alt-thiophene (P1 and P2) and perylene-diimide-alt-thiophene (P3 and P4) based donor-π-acceptor (D-π-A) copolymers have been synthesized from the corresponding monomers through Pd-catalyzed Sonogashira polymerization protocol. The well defined and soluble π-conjugated copolymers having alkyl and fluoroalkyl substituents (P1-P4) have been characterized by multinuclear NMR spectra as well as by tetradetector GPC studies showing molecular weight (Mn) in the range of 18-20 kDa with good polydispersity indices of 1.31-1.48. The donor-acceptor based copolymers absorb broadly throughout the visible region. Notably, perylene diimide-thiophene based copolymers (P3 and P4) exhibits an absorption onset at ca. 800 nm corresponding to a bandgap of 1.63 and 1.61 eV (Egopt). DFT computational studies of the model π-conjugated units have also been investigated to understand the molecular geometries and electronic properties of the polymeric unit. The synthesized D-π-A polymers have been utilized as active materials for polymer-sensitized solar cells (PSSCs). The copolymers are effectively adsorbed onto the surface of nanostructured TiO2 photoanode as a result of facile interaction of the anchored -C=O units with the metal oxide surface. The spectral profile of the polymer films on mesoporous oxide surface approximately similar to the solution absorption spectra of the polymer. Interestingly, the polymers featuring perylene diimide unit (P3 and P4) exhibit promising power conversion efficiency (PCE) of 2.71 and 2.96% with a short circuit current (JSC) of 7.54 and 7.85 mA·cm-2 respectively, and IPCE of 42-45% under 1.5 AM illumination.
关键词： Dye Sensitized Solar Cells,Polymer Sensitizers,Thiophene,Perylene-diimide,Diketopyrrolopyrrole,Low Bandgap,D-π-A
更新于2025-09-12 10:27:22
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Tandems in the thick of it
摘要： Two-terminal all-perovskite tandem structures are promising as low-cost yet highly efficient solar cells, but their development is limited by the poor quality of the low bandgap absorber layer. Now, a processing method has been shown to enable the production of uniform, thick tin–lead perovskite layers, which translate into improved photovoltaic parameters.
关键词： perovskite photovoltaics,low bandgap absorber,power conversion efficiency,tin–lead perovskite,tandem solar cells
更新于2025-09-09 09:28:46