Single-Junction Binary-Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency

A new fluorinated nonfullerene acceptor, ITIC-Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end-capping group 1,1-dicyanomethylene-3-indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push–pull effect between the donor unit indacenodithieno[3,2-b]thiophene and the acceptor unit IC due to electron-withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short-circuit current density (JSC). On the other hand, incorporation of F would improve intermolecular interactions through C-F···S, C-F···H, and C-F···π noncovalent interactions and enhance electron mobility, which is beneficial to enhancing JSC and fill factor. Indeed, the results show that fluorinated ITIC-Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC-Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC-Th1 electron acceptor and a wide-bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC-Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene-based single-junction binary-blend OSCs. Moreover, the OSCs based on FTAZ:ITIC-Th1 show much better efficiency and better stability than the control devices based on FTAZ:PC71BM (PCE = 5.22%)

Karriere-Handbuch

We design and synthesize four fused-ring electron acceptors based on 6,6,12,12-tetrakis(4-hexylphenyl)- indacenobis(dithieno[3,2-b;2′,3′-d]thiophene) as the electron- rich unit and 1,1-dicyanomethylene-3-indanones with 0− 2 fluorine substituents as the electron-deficient units. These four molecules exhibit broad (550−850 nm) and strong absorption with high extinction coefficients of (2.1−2.5) × 105 M−1 cm−1. Fluorine substitution downshifts the LUMO energy level, red-shifts the absorption spectrum, and enhances electron mobility. The polymer solar cells based on the fluorinated electron acceptors exhibit power conversion efficiencies as high as 11.5%, much higher than that of their nonfluorinated counterpart (7.7%). We investigate the effects of the fluorine atom number and position on electronic properties, charge transport, film morphology, and photovoltaic properties

Some details of experiments

The file includes 1. Synthesis of P(PDI-DTT) 2. Schematic of gold-layer sticking technique 3. More photographs of nanotube

Data from: Convenient fabrication of conjugated polymer semiconductor nanotubes and their application in organic electronics

Organic heterojunction is indispensable in organic electronic devices, such as organic solar cells (OSCs), organic light-emitting diodes (OLEDs) and so on. Fabrication of core-shell nanostructure provides feasible and novel way to prepare organic heterojunction, which is beneficial for miniaturization and integration of organic electronic devices. Fabrication of nanotubes which constitute the core-shell structure in large quantity is the key for the realization of application. In this work, a simple and convenient method to prepare nanotubes utilizing conjugated copolymer of perylene diimide and dithienothiophene (P(PDI-DTT)) was demonstrated. The relationship between preparation condition (solvent atmosphere, solution concentration and pore diameter of templates) and morphology of nanostructure was studied systematically. P(PDI-DTT) nanotubes could be fabricated in regular shape and large quantity by preparing the solution with appropriate concentration and placing Anodic Aluminum Oxide (AAO) template with nanopore diameter of 200 nm in the solvent atmosphere. The tubular structure was confirmed by scanning electron microscope (SEM). P(PDI-DTT) nanotubes exhibited electron mobility of 0.02 cm2V-1s–1 in field effect transistors under ambient condition. Light emitting nanostructures were successfully fabricated by incorporating tetraphenyl ethylene (TPE) into polymer nanotubes

Data from: Convenient fabrication of conjugated polymer semiconductor nanotubes and their application in organic electronics

Organic heterojunction is indispensable in organic electronic devices, such as organic solar cells (OSCs), organic light-emitting diodes (OLEDs) and so on. Fabrication of core-shell nanostructure provides feasible and novel way to prepare organic heterojunction, which is beneficial for miniaturization and integration of organic electronic devices. Fabrication of nanotubes which constitute the core-shell structure in large quantity is the key for the realization of application. In this work, a simple and convenient method to prepare nanotubes utilizing conjugated copolymer of perylene diimide and dithienothiophene (P(PDI-DTT)) was demonstrated. The relationship between preparation condition (solvent atmosphere, solution concentration and pore diameter of templates) and morphology of nanostructure was studied systematically. P(PDI-DTT) nanotubes could be fabricated in regular shape and large quantity by preparing the solution with appropriate concentration and placing Anodic Aluminum Oxide (AAO) template with nanopore diameter of 200 nm in the solvent atmosphere. The tubular structure was confirmed by scanning electron microscope (SEM). P(PDI-DTT) nanotubes exhibited electron mobility of 0.02 cm2V-1s–1 in field effect transistors under ambient condition. Light emitting nanostructures were successfully fabricated by incorporating tetraphenyl ethylene (TPE) into polymer nanotubes

Data from: Convenient fabrication of conjugated polymer semiconductor nanotubes and their application in organic electronics

Organic heterojunction is indispensable in organic electronic devices, such as organic solar cells (OSCs), organic light-emitting diodes (OLEDs) and so on. Fabrication of core-shell nanostructure provides feasible and novel way to prepare organic heterojunction, which is beneficial for miniaturization and integration of organic electronic devices. Fabrication of nanotubes which constitute the core-shell structure in large quantity is the key for the realization of application. In this work, a simple and convenient method to prepare nanotubes utilizing conjugated copolymer of perylene diimide and dithienothiophene (P(PDI-DTT)) was demonstrated. The relationship between preparation condition (solvent atmosphere, solution concentration and pore diameter of templates) and morphology of nanostructure was studied systematically. P(PDI-DTT) nanotubes could be fabricated in regular shape and large quantity by preparing the solution with appropriate concentration and placing Anodic Aluminum Oxide (AAO) template with nanopore diameter of 200 nm in the solvent atmosphere. The tubular structure was confirmed by scanning electron microscope (SEM). P(PDI-DTT) nanotubes exhibited electron mobility of 0.02 cm2V-1s–1 in field effect transistors under ambient condition. Light emitting nanostructures were successfully fabricated by incorporating tetraphenyl ethylene (TPE) into polymer nanotubes

Breaking 10% Efficiency in Semitransparent Solar Cells with Fused-Undecacyclic Electron Acceptor

A fused-undecacyclic electron acceptor IUIC has been designed, synthesized and applied in organic solar cells (OSCs) and semitransparent organic solar cells (ST-OSCs). In comparison with its counterpart, fused-heptacyclic ITIC4, IUIC with a larger π-conjugation and a stronger electron-donating core exhibits a higher LUMO level (IUIC: −3. 87 eV vs ITIC4: −3.97 eV), 82 nm red-shifted absorption with larger extinction coefficient and smaller optical bandgap, and higher electron mobility. Thus, IUIC-based OSCs show higher values in open-circuit voltage, short-circuit current density, and thereby much higher power conversion efficiency (PCE) than those of the ITIC4-based counterpart. The as-cast OSCs based on PTB7-Th: IUIC without any extra treatment yield PCEs of up to 11.2%, higher than that of the control devices based on PTB7-Th: ITIC4 (8.18%). The as-cast ST-OSCs based on PTB7-Th: IUIC without any extra treatment afford PCEs of up to 10.2% with an average visible transmittance (AVT) of 31%, higher than those of the control devices based on PTB7-Th: ITIC4 (PCE = 6.42%, AVT = 28%)

Single‐Junction Binary‐Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency

A new fluorinated nonfullerene acceptor, ITIC-Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end-capping group 1,1-dicyanomethylene-3-indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push-pull effect between the donor unit indacenodithieno[3,2-b] thiophene and the acceptor unit IC due to electron-withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short-circuit current density (JSC). On the other hand, incorporation of F would improve intermolecular interactions through C. F center dot center dot center dot S, C. F center dot center dot center dot H, and C. F center dot center dot center dot pi noncovalent interactions and enhance electron mobility, which is beneficial to enhancing JSC and fill factor. Indeed, the results show that fluorinated ITIC-Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC-Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC-Th1 electron acceptor and a wide-bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC-Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene-based single-junction binary-blend OSCs. Moreover, the OSCs based on FTAZ: ITIC-Th1 show much better efficiency and better stability than the control devices based on FTAZ: PC71BM (PCE = 5.22%).973 Program [2013CB834702]; National Natural Science Foundation of China [91433114]; Office of Naval Research [N000141410221]; National Science Foundation [DMR-1507249]; Ministry of Science and Technology [2016YFA0200700]; NSFC [21504066, 21534003]; Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy [DE-AC02-05CH11231]SCI(E)ARTICLE182

Effect of Core Size on Performance of Fused-Ring Electron Acceptors

We report 4 fused-ring electron acceptors (FREAs) with the same end-groups and side-chains but different cores, whose sizes range from 5 to 11 fused rings. The core size has considerable effects on the electronic, optical, charge transport, morphological, and photovoltaic properties of the FREAs. Extending the core size leads to red-shift of absorption spectra, upshift of the energy levels, and enhancement of molecular packing and electron mobility. From 5 to 9 fused rings, the core size extension can simultaneously enhance open-circuit voltage (<i>V</i>_OC), short-circuit current density (<i>J</i>_SC), and fill factor (FF) of organic solar cells (OSCs). The best efficiency of the binary-blend devices increases from 5.6 to 11.7%, while the best efficiency of the ternary-blend devices increases from 6.3 to 12.6% as the acceptor core size extends

Photophysical pathways in efficient bilayer organic solar cells: The importance of interlayer energy transfer

The development of organic photovoltaic (OPV) cells has long been guided by the idea that excitons - bound electron-hole pairs created by light absorption - diffuse only 5-10 nm. True for many materials, this constraint led to an inherently complex device architecture - the bulk heterojunction - that has obscured our understanding of device physics, and handicapped rational material design. Here, we investigate the photophysics of a series of planar bilayer heterojunction devices incorporating fused-ring electron acceptors with power conversion efficiencies up to 11%. Using ultrafast optical spectroscopy, we demonstrate the importance of long-range layer-tolayer energy transfer in planar structures, isolating this effect by including an insulating layer between the donor and acceptor layers to eliminate charge transfer effects. We show that the slab geometry facilitates substantially longer-range energy transfer than between isolated molecules or small domains. Along with high molecular packing densities, high absorption coefficients, and long exciton diffusion lengths, we show that these effects amount to exciton harvesting length scales that match the light absorption lengths and thereby enable efficient bilayer devices. Our quantitative analysis of bilayer structures also accounts for large domain sizes in bulkheterojunction devices including fused-ring electron acceptors, and it quantifies the importance of strong resonant spectral overlap is for material selection and design for highly efficient OPVs