Organic photovoltaic cells (OPVs) are a promising cost-effective alternative to silicon-based solar cells, and possess light-weight, low-cost, and flexibility advantages. Significant progress has been achieved in the development of novel photovoltaic materials and device structures in the last decade. Nowadays small molecular semiconductors for OPVs have attracted considerable attention, due to their advantages over their polymer counterparts, including well-defined molecular structure, definite molecular weight, and high purity without batch to batch variations. The highest power conversion efficiencies of OPVs based on small molecular donor/fullerene acceptors or polymeric donor/fullerene acceptors are up to 6.7% and 8.3%, respectively, and meanwhile nonfullerene acceptors have also exhibited some promising results. In this review we summarize the developments in small molecular donors, acceptors (fullerene derivatives and nonfullerene molecules), and donor–acceptor dyad systems for high-performance multilayer, bulk heterojunction, and single-component OPVs. We focus on correlations of molecular chemical structures with properties, such as absorption, energy levels, charge mobilities, and photovoltaic performances. This structure–property relationship analysis may guide rational structural design and evaluation of photovoltaic materials (253 references).

Small molecule semiconductors for high-efficiency organic photovoltaics

The present invention provides a heterocyclic compound and an organic light-emitting device including the heterocyclic compound. The organic light-emitting devices using the heterocyclic compounds have high-efficiency, low driving voltage, high luminance and long lifespan.

Organic light-emitting device

Phosphorescent organic light-emitting devices (OLEDs) have attracted increased attention from both academic and industrial communities due to their potential practical application in high-resolution full-color displays and energy-saving solid-state lightings. The performance of phosphorescent OLEDs is mainly limited by the phosphorescent transition metal complexes (such as iridium(III), platinum(II), gold(III), ruthenium(II), copper(I) and osmium(II) complexes, etc.) which can play a crucial role in furnishing efficient energy transfer, balanced charge injection/transporting character and high quantum efficiency in the devices. It has been shown that functionalized main-group element (such as boron, silicon, nitrogen, phosphorus, oxygen, sulfur and fluorine, etc.) moieties can be incorporated into phosphorescent emitters and their host materials to tune their triplet energies, frontier molecular orbital energies, charge injection/transporting behavior, photophysical properties and thermal stability and hence bring about highly efficient phosphorescent OLEDs. So, in this review, the recent advances in the phosphorescent emitters and their host materials functionalized with various main-group moieties will be introduced from the point of view of their structure-property relationship. The main emphasis lies on the important role played by the main-group element groups in addressing the key issues of both phosphorescent emitters and their host materials to fulfill high-performance phosphorescent OLEDs.

Functionalization of phosphorescent emitters and their host materials by main-group elements for phosphorescent organic light-emitting devices.

N-Heterocyclic carbene Ir(III) complexes, used as deep blue phosphorescent emitters and as electron-blocking dopants in organic LEDs, allow the realization of devices with very high brightness and reduced efficiency roll-off.

Deep blue phosphorescent organic light-emitting diodes with very high brightness and efficiency

Charge carrier recombination in organic solar cells

In this study the charge dissociation at the donor/acceptor heterointerface of thermally evaporated planar heterojunction merocyanine/C60 organic solar cells is investigated. Deposition of the donor material on a heated substrate as well as post-annealing of the complete devices at temperatures above the glass transition temperature of the donor material results in a twofold increase of the fill factor. An analytical model employing an electric-fielddependent exciton dissociation mechanism reveals that geminate recombination is limiting the performance of as-deposited cells. Fourier-transform infrared ellipsometry shows that, at temperatures above the glass transition temperature of the donor material, the orientation of the dye molecules in the donor films undergoes changes upon annealing. Based on this finding, the influence of the dye molecules’ orientations on the charge-transfer state energies is calculated by quantum mechanical/molecular mechanics methods. The results of these detailed studies provide new insight into the exciton dissociation process in organic photovoltaic devices, and thus valuable guidelines for designing new donor materials.

Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance

Cyclometallated iridium carbene complexes are introduced as efficient blue triplet emitters. Quantum mechanical calculations have been used to design and to optimize this class of materials predominantely with respect to color coordinates and luminescence quantum yield. To complete the set of materials required for deep blue OLED devices we engineered suitable host and blocker materials for the use in combination with large triplet energy carbene emitters. These tailor-made materials were applied to develop deep blue electroluminescent devices with excellent efficiency.

11.2: Efficient Deep Blue Triplet Emitters for OLEDs

Thermal co-evaporation of C(60) fullerene and two merocyanine dyes affords bulk heterojunction solar cells with improved short-circuit currents and power conversion efficiencies in comparison with the respective single donor cells. These results are rationalized by the formation of three distinct subphases driven by differences in molecular shape and electrostatic interactions.

Parallel Bulk‐Heterojunction Solar Cell by Electrostatically Driven Phase Separation

Die Erfindung betrifft Verbindungen der ahgemeinen Formell The invention relates to compounds of ahgemeinen Formally in der in the X Fluor, Chlor, Brom, SO z E oder gegebenenfalls substituiertes Hydroxy oder Mercapto, X is fluorine, chlorine, bromine, SO z E or optionally substituted hydroxyl or mercapto, E Alkyl, Alkenyl, Cycloalkyl, Aralkyl, Aryl, Chlor oder gegebenenfalls substituiertes Hydroxy oder Amino, E is alkyl, alkenyl, cycloalkyl, aralkyl, aryl, chlorine or optionally substituted hydroxy or amino, Y Cyan, Nitro, Alkanoyl, Aroyl, Alkylsulfonyl, Arylsulfonyl, Carboxyl, Carbonester oder gegebenenfalls substituiertes Carbamoyl, Y cyano, nitro, alkanoyl, aroyl, alkylsulfonyl, arylsulfonyl, carboxyl, carboxylic ester, or optionally substituted carbamoyl, T Wasserstoff, C i - bis C 4 -Alkyl, ein durch elektrophile Substitution einfuhrbarer Rest oder ein Rest der Formel -CH=B, wobei B der Rest einer methylenaktiven Verbindung odar eines Amins ist, und T is hydrogen, C i - to C 4 -alkyl, an insertable by electrophilic substitution radical or a radical of the formula -CH = B, where B is the residue of an active methylene compound odar an amine, and K der Rest einer Kupplungskomponente sind. K is the radical of a coupling component. Die erfindungsgemasen Verbindungen eignen sich sehr gut zum Farben synthetischer Fasern oder von Kunststoffen. The compounds of the invention are highly suitable for the dyeing of synthetic fibers or plastics.

Dyestuffs with thiophene rests

Triazolopyridinfarbstoffe der Formel A triazolopyridine dye of the formula in der in the R¹ gegebenenfalls substituiertes C₁-C₂₀-Alkyl, gegebenenfalls substituiertes Phenyl oder Hydroxy, R¹ represents optionally substituted C₁-C₂₀-alkyl, optionally substituted phenyl or hydroxy; R² einen carbocyclischen oder heterocyclischen Rest, R² represents a carbocyclic or heterocyclic radical, R³ Cyano, Carbamoyl, Carboxyl oder C₁-C₄-Alkoxycarbonyl, R³ is cyano, carbamoyl, carboxyl or C₁-C₄-alkoxycarbonyl, R⁴ Sauerstoff oder einen Rest der Formel R⁴ is oxygen or a radical of the formula wobei L¹ fur C₁-C₈-Alkyl, das gegebenenfalls durch 1 oder 2 Sauerstoffatome unterbrochen ist, steht, und wherein L¹ is C₁-C₈-alkyl which is optionally interrupted by 1 or 2 oxygen atoms, is, and X CH oder Stickstoff bedeuten, X is CH or nitrogen mean sowie ein Verfahren zum thermischen Transfer von Methinfarbstoffen. and a method for thermal transfer of methine dyes.

Helmut Dr Reichelt

Papers

Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance

11.2: Efficient Deep Blue Triplet Emitters for OLEDs

Parallel Bulk‐Heterojunction Solar Cell by Electrostatically Driven Phase Separation

Dyestuffs with thiophene rests

Triazole pyridine dyes and a thermal transfer process of methine dyes