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Efficient CsPbBr3 Inorganic Perovskite Light-Emitting Diodes via Lewis Acid-Base Reaction with Organic Small Molecule mCP
摘要： CsPbBr3 all-inorganic perovskite light-emitting diodes (PeLEDs) have received increasing attention in recent years due to their unique luminescent property and superior thermal stability. However, the low solubility of bromide precursors and the fast crystallization of perovskites usually cause the formation of discontinuous CsPbBr3 films with rough grains and large pin-holes. This would increase the defects and non-radiative recombination and severely degrade the device electroluminescence (EL) performance. To tackle this issue, herein, the 1,3-bis9H-carbazol-9-ylbenzene (mCP) small molecule was elaborately selected as an effective additive to enhance the film-forming ability of CsPbBr3 emissive layers. With the addition of mCP, the submicron-sized CsPbBr3 grains were reduced to nanometer range, and the resulting perovskite films became uniform and continuous. It was found that the electron pairs of N2- in mCP would donate to metal Pb2+ in CsPbBr3. Thus the so-called Lewis acid-base reaction occurred, which could retard the fast crystallization process and contribute to the connection of perovskite grains. As such, the film roughness was decreased from 8.28 nm to 1.62 nm, and the carrier lifetime was increased from 2.49 ns to 68.39 ns. The CsPbBr3:mCP device with an optimized mass ratio of 1:0.10 exhibited a maximum luminance (L) of 21008 cd/m2, a maximum current efficiency (CE) of 3.74 cd/A, and the corresponding maximum external quantum efficiency (EQE) of 1.21%, far surpassing the EL performance of the pristine CsPbBr3 PeLEDs.
关键词： Organic small molecule mCP,Effective additive,CsPbBr3 inorganic perovskite,Lewis acid-base reaction,Light-emitting diodes
更新于2025-09-16 10:30:52
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Star-shaped A-D-A compounds synthesized by different methods and used as donor or acceptor materials in organic photovoltaics
摘要： Star-shaped small molecule has lots of fascinating advantages compare with the linear small molecule. In this paper, two star-shaped small-molecules (S-TT and S-TT-R) with vinyl trithiophene with or without alkyl substituents as core, N-ethyl- rhodanine as terminal and withdrawing groups, vinyl as bridge group were synthesized by different synthetic routes. Both of the two materials demonstrate high thermal stability and broad absorption. Both S-TT and S-TT-R exhibit narrow bandgap (1.72 and 1.82 eV), low LUMO energy levels (? 3.92 eV) for S-TT and high HOMO energy levels (? 5.37 eV) for S-TT-R which could be applied as acceptor or donor materials for photovoltaics, respectively. Both of the two compounds were used as donor materials with PC61BM acceptor and S-TT were used as acceptor material with P3HT donor.
关键词： Absorption,Star-shaped small molecule,Organic photovoltaics,Acceptor materials,Thermal stability,Donor materials
更新于2025-09-16 10:30:52
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An all small molecule organic solar cell based on a porphyrin donor and a non-fullerene acceptor with complementary and broad absorption
摘要： A thieno[3,2-b]thiophene-functionalized porphyrin molecule (DEP-TT) with the ethynylene bridges between the diketopyrrolopyrrole and porphyrin units has been designed and synthesized as the donor material. DEP-TT exhibits a broad absorption wavelength in the visible region with the onset absorption to 898 nm of the film and a low optical band gap of 1.38 eV. IDT-C8, as the acceptor material has a relatively strong absorption spectrum ranging from 500-750 nm in the solid film, which exactly fills the absorption trough of DEP-TT. The power conversion efficiency (PCE) of all small molecule increased from 0.64% (Jsc = 2.61 mA cm-2, Voc = 0.82 V, and FF = 0.30) to 5.14% (Jsc = 11.15 mA cm-2, Voc = 0.71 V, and FF = 0.65) after solvent vapor annealing. The PCE of 5.14% provided valuable recommendation based on porphyrin all small molecule system, since few work has involved in this field.
关键词： organic solar cells,all small molecule,complementary absorption,porphyrin
更新于2025-09-16 10:30:52
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Novel Small Four-armed Molecules with Triphenylamine-bridged Structure for Organic Solar Cells Featuring High Open-circuit Voltage
摘要： In view of few attention on star-shaped molecules containing triphenylamine(TPA) unit as π-linker, a series of small four-armed molecules, consisting of octyloxy-substituted 2,1,3-benzothiadiazole(DOBT) or 4-octyl-2-thienyl functionalized DOBT as the core, TPA as π-bridge and 4-methylphenyl or 4-methoxyphenyl groups as terminal units, was designed and synthesized. The effects of π-bridges and substitute groups on molecular photoelectric performance and photovoltaic performance were fully explored. With the help of the additional thiophene-linkers incorporation, 3-octylthienyl substituted molecule with end-capping 4-methylphenyl(T-BTTPAM) and 3-octylthienyl substituted molecule with end-capping 4-methoxyphenyl(T-BTTPAOM) showed stronger and broader absorption, as well as higher charge mobilities compared to the molecules without thiophene-linkers(BTTPAM and BTTPAOM). Additionally, changing substitute groups from methyl to methoxy helped BTTPAOM and T-BTTPAOM achieve better absorption properties than BTTPAM and T-BTTPAM, respectively. When paired with PC61BM as the electron acceptor to fabricate solution-processed photovoltaic devices, the four materials gave high open-circuit voltage(Voc) values over 0.90 V. These results demonstrate that our materials are promising candidates as donor materials for organic solar cells(OSCs), and further device optimization is in progress in our laboratory.
关键词： Organic solar cell,Triphenylamine,Four-armed structure,High open-circuit voltage,Small-molecule donor
更新于2025-09-16 10:30:52
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13.34% Efficiency Nonfullerene All-Small-Molecule Organic Solar Cells Enabled by Modulating Crystallinity of Donors via a Fluorination Strategy
摘要： Nonfullerene all-small-molecule organic solar cells (NFSM-OSCs) have shown a promising potential towards the commercialization of OSCs, owing to their unique advantages of high purity, easy synthesis and good reproducibility. However, great challenges in the modulation of phase separation morphology have limited their future development. Herein, two novel small molecular donors of BTEC-1F and BTEC-2F, derived from the small molecule DCAO3TBDTT, were designed and synthesized. While using Y6 as the acceptor, the devices based on non-fluorinated DCAO3TBDTT showed an open circuit voltage (Voc) of 0.804 V and a power conversion efficiency (PCE) of 10.64%. Mono-fluorinated BTEC-1F showed an increased Voc of 0.870 V and a PCE of 11.33%. More impressively, the fill factor (FF) of di-fluorinated BTEC-2F based NFSM-OSC was largely improved to 72.35% resulting in an impressive PCE of 13.34%, which was much higher than that of BTEC-1F (61.35%) and DCAO3TBDTT (60.95%). To the best of our knowledge, this is the highest reported PCE to date for NFSM-OSCs. BTEC-2F depicted a more compact molecular stacking and a lower crystallinity as revealed from characterization studies, which was beneficial for enhancing phase separation and carrier transport. Those results demonstrated an effective strategy to improve the performance of NFSM-OSCs via fluorination of small molecular donors and modulation of crystallinity deviation between donors and acceptors.
关键词： morphology,all-small-molecule organic solar cells,crystallinity,fluorination,orientation modulation
更新于2025-09-12 10:27:22
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13.7% Efficiency Small‐Molecule Solar Cells Enabled by a Combination of Material and Morphology Optimization
摘要： Compared with the quick development of polymer solar cells, achieving high-efficiency small-molecule solar cells (SMSCs) remains highly challenging, as they are limited by the lack of matched materials and morphology control to a great extent. Herein, two small molecules, BSFTR and Y6, which possess broad as well as matched absorption and energy levels, are applied in SMSCs. Morphology optimization with sequential solvent vapor and thermal annealing makes their blend films show proper crystallinity, balanced and high mobilities, and favorable phase separation, which is conducive for exciton dissociation, charge transport, and extraction. These contribute to a remarkable power conversion efficiency up to 13.69% with an open-circuit voltage of 0.85 V, a high short-circuit current of 23.16 mA cm?2 and a fill factor of 69.66%, which is the highest value among binary SMSCs ever reported. This result indicates that a combination of materials with matched photoelectric properties and subtle morphology control is the inevitable route to high-performance SMSCs.
关键词： morphology,energy loss,power conversion efficiency,small-molecule solar cells,nonfullerene acceptors
更新于2025-09-12 10:27:22
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Nonhalogenated-Solvent-Processed Efficient Polymer Solar Cells Enabled by Medium-Band-Gap A?π–D?π–A Small-Molecule Acceptors Based on a 6,12-Dihydro-diindolo[1,2- <i>b</i> :10,20- <i>e</i> ]pyrazine Unit
摘要： In this contribution, a series of A?π?D?π?A small molecules (SMs), IPY-T-IC, IPY-T-ICCl, and IPY-T-ICF, containing the central donor unit (D) of 6,12-dihydro-diindolo[1,2-b:10,20-e]pyrazine (IPY), the π-conjugated bridge of thiophene, and the end-accepting group (A) of 3-(dicyanomethylidene)indol-1-one, 5,6-dichloro-3-(dicyanomethylidene)indol-1-one, or 5,6-difluoro-3-(dicyanomethylene)indol-1-one, were developed, characterized, and employed as the acceptor materials for polymer solar cells (PSCs). Influences of the different end-accepting groups on thermal properties, spectral absorption, energy levels, photovoltaic performance, and film morphology of these small-molecule acceptors (SMAs) were investigated in detail. These SMAs exhibit an excellent thermal stability and strong crystallization. The absorption spectra of these SMs mainly locate the wavelength between 400 and 700 nm, associated with the optical band gaps in the range of 1.75?1.90 eV. Compared with nonhalogenated IPY-T-IC, the halogenated SMAs IPY-T-ICCl and IPY-T-ICF present better absorption abilities, wider absorption region, and downshifted highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels. With regard to the complementary spectral absorption and matched HOMO/LUMO levels, PTB7-Th as a low-band gap polymer was chosen to be an electron donor to pair with these SMAs for fabricating bulk-heterojuntion PSCs. Under optimized conditions, among these SMAs, the PTB7-Th:IPY-T-IC-based PSC processed from a halogenated solvent system (chlorobenzene + 1-chloronaphthalene) delivers the best power conversion efficiency (PCE) of 7.32%, mainly because of more complementary spectral absorption, upper-lying LUMO level, higher and balanced carrier mobility, more efficiently suppressed trap-assisted recombination, better charge collection property, and blend morphology. Encouragingly, an improved PCE of up to 7.68% is achieved when the IPY-T-IC-based solar cell was processed from a nonhalogenated solvent system (o-xylene + 2-methylnaphthalene). In view of the large band gap of these IPY-based SMAs, the PCE of over 7.5% is notable and attractive for the related community. Our study argues that the IPY moiety is a potential electron-donating building moiety to develop medium-band-gap high-performance A?π?D?π?A SMAs for nonhalogenated-solvent-processed photovoltaic devices.
关键词： A?π?D?π?A,polymer solar cells,small-molecule acceptors,6,12-dihydro-diindolo[1,2-b:10,20-e]pyrazine,photovoltaic performance
更新于2025-09-12 10:27:22
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13.34% Efficiency Nonfullerene All‐Small‐Molecule Organic Solar Cells Enabled by Modulating Crystallinity of Donors via a Fluorination Strategy
摘要： Nonfullerene all-small-molecule organic solar cells (NFSM-OSCs) have shown a promising potential towards the commercialization of OSCs, owing to their unique advantages of high purity, easy synthesis and good reproducibility. However, great challenges in the modulation of phase separation morphology have limited their future development. Herein, two novel small molecular donors of BTEC-1F and BTEC-2F, derived from the small molecule DCAO3TBDTT, were designed and synthesized. While using Y6 as the acceptor, the devices based on non-fluorinated DCAO3TBDTT showed an open circuit voltage (Voc) of 0.804 V and a power conversion efficiency (PCE) of 10.64%. Mono-fluorinated BTEC-1F showed an increased Voc of 0.870 V and a PCE of 11.33%. More impressively, the fill factor (FF) of di-fluorinated BTEC-2F based NFSM-OSC was largely improved to 72.35% resulting in an impressive PCE of 13.34%, which was much higher than that of BTEC-1F (61.35%) and DCAO3TBDTT (60.95%). To the best of our knowledge, this is the highest reported PCE to date for NFSM-OSCs. BTEC-2F depicted a more compact molecular stacking and a lower crystallinity as revealed from characterization studies, which was beneficial for enhancing phase separation and carrier transport. Those results demonstrated an effective strategy to improve the performance of NFSM-OSCs via fluorination of small molecular donors and modulation of crystallinity deviation between donors and acceptors.
关键词： morphology,all-small-molecule organic solar cells,crystallinity,fluorination,orientation modulation
更新于2025-09-12 10:27:22
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Di‐fluorinated Oligothiophenes for High‐Efficiency All‐Small‐Molecule Organic Solar Cells: Positional Isomeric Effect of Fluorine Substitution on Performance Variations
摘要： Three symmetrically di-fluorinated organic semiconductors (namely D5T2F-P, D5T2F-S, and D5T2F-T) containing rhodanine-flanked pentathiophene structures are synthesized and used as donors in all-small-molecule organic solar cells (ASM-OSCs) prepared with the small-molecule acceptor 2,2'-((2Z,2'Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC-4F). The different substitutional positions of the fluorine atoms (-F) in the conjugated backbone of the donor molecule leads to various material and photovoltaic properties being exhibited. Among the three isomers, the centrally-fluorinated D5T2F-P exhibits a redshifted absorption spectrum, downshifted highest occupied molecular orbital (HOMO) energy level, and improved miscibility with IDIC-4F in the blend films, all of which result in superior device performance. The power conversion efficiency (PCE) of the ASM-OSCs based on D5T2F-P:IDIC-4F reaches the impressive value of 9.36% with an open-circuit voltage (VOC) value of 0.86 V and a short-circuit current density (JSC) value of 16.94 mA/cm2, while those of D5T2F-S (6.11%) and D5T2F-T (5.42%) are much lower. In comparison, an ASM-OSC based on the non-fluorinated analogue DRCN5T fabricated under the same conditions exhibits poorer performance (8.03% with IDIC-4F), revealing a 16% enhancement in PCE achieved through backbone fluorination. To the best of our knowledge, the PCE of 9.36% is one of the highest efficiencies of oligothiophene-based ASM-OSCs reported in the literature to date.
关键词： organic solar cells,binding energy,small molecule donors,fluorination,non-fullerene
更新于2025-09-12 10:27:22
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Imaging of Tie2 with a Fluorescently Labeled Small Molecule Affinity Ligand
摘要： The receptor tyrosine kinase inhibitor, Tie2, has significant roles in endothelial signaling and angiogenesis, and is relevant in the pathophysiology of several diseases. However, there are relatively few small molecule probes available to study Tie2, making evaluation of its activity in vivo difficult. Recently, it was discovered that the small molecule, rebastinib (DCC-2036), is a potent Tie2 inhibitor. We hypothesized that fluorescent derivatives of rebastinib could be used as imaging agents for Tie2. Based on crystallography structures, we synthesized three fluorescent derivatives, which we then evaluated in both in vitro and in vivo assays. We found that the Rebastinib-BODIPY TMR (Reb-TMR) derivative has superior imaging characteristics in vitro, and successfully labeled endothelial cells in vivo. We propose that this probe could be further used in in vivo applications for studying the role of Tie2 in disease.
关键词： small molecule probes,rebastinib,Tie2,imaging agents,fluorescent derivatives,receptor tyrosine kinase,angiogenesis
更新于2025-09-12 10:27:22