We present highly efficient Tb(III)-based organic light-emitting diodes optimized by the subtle choice of bipolar hosts, adjacent layers and double emitting structures. By introducing di(9H-carbazol-9-yl)(phenyl) phosphine oxide (DCPPO) as the host for the first emitting layer, and 9-(4-tert-butylphenyl)-3,6-bis(diphenylphosphine oxide)-carbazole (DPPOC) for the second emitting layer for Tb(PMIP)(3) (PMIP stands for 1-phenyl-3-methyl-4-isobutyryl-pyrazol-5-one), the excitons can be well confined within the double-emitting layer. When 4,4',4 `'-tris(N-carbazolyl) triphenylamine (TCTA) and tris-[3-(3-pyridyl)mesityl] borane (3TPYMB) with high triplet energy levels are used as a hole transporting layer (HTL) and an electron transporting layer (ETL), respectively, the optimized device reaches a maximum efficiency of 52 lm W-1, 57 cd A(-1), i.e. a maximum external quantum efficiency (EQE) of 15%. At a practical brightness of 100 cd m(-2) (4.6 V) the efficiency remains at around 20 lm W-1, 30 cd A(-1).

Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.

We present highly efficient Tb(III)-based organic light-emitting diodes optimized by the subtle choice of bipolar hosts, adjacent layers and double emitting structures. By introducing di(9H-carbazol-9-yl)(phenyl) phosphine oxide (DCPPO) as the host for the first emitting layer, and 9-(4-tert-butylphenyl)-3,6-bis(diphenylphosphine oxide)-carbazole (DPPOC) for the second emitting layer for Tb(PMIP)(3) (PMIP stands for 1-phenyl-3-methyl-4-isobutyryl-pyrazol-5-one), the excitons can be well confined within the double-emitting layer. When 4,4',4 `'-tris(N-carbazolyl) triphenylamine (TCTA) and tris-[3-(3-pyridyl)mesityl] borane (3TPYMB) with high triplet energy levels are used as a hole transporting layer (HTL) and an electron transporting layer (ETL), respectively, the optimized device reaches a maximum efficiency of 52 lm W-1, 57 cd A(-1), i.e. a maximum external quantum efficiency (EQE) of 15%. At a practical brightness of 100 cd m(-2) (4.6 V) the efficiency remains at around 20 lm W-1, 30 cd A(-1).

Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.

During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid (PEDOT:PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT:PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (V-oc) of 0.99 V, a short-circuit current (J(sc)) of 23.2 mA cm(-2) and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PEDOT:PSS layer, indicating that CuOx could be a promising HTM for replacing PEDOT:PSS in inverted planar heterojunction perovskite solar cells.

Ultrasmooth perovskite thin films are prepared by a solution-based one-step micro-flowing anti-solvent deposition (MAD) method carried out in air with simplicity and practicability. Engaging inert gas blow and anti-solvent drips as accelerators, ultrafast crystallizing, thickness controllable, and high quality methylammonium lead iodide films are prepared with a least root mean square roughness of 1.43 nm (1.95 nm on average), achieving the smoothest surface morphology to the best of our knowledge, as well as a rather compact perovskite layer with a high coverage ratio. Perovskite films formed from MAD require no annealing procedure to ultimately crystallize, realizing a very fast crystallizing procedure within few seconds. By controlling the thickness of perovskite films, superior photovoltaic performance of solar cells with a large fill factor of 0.8 and a PCE of 15.98% is achieved without a glovebox. MAD technology will benefit not only highly efficient photovoltaic devices, but also perovskite-based hybrid optoelectronic devices with field effect transistors and light emitting diodes as well.

In high performance perovskite based solar cells, CH3NH3PbI3 is the key material. We carried out a study on charge diffusion in spin-coated CH3NH3PbI3 perovskite thin film by transient fluorescent spectroscopy. A thickness-dependent fluorescent lifetime was found. By coating the film with an electron or hole transfer layer, [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) or 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) respectively, we observed the charge transfer directly through the fluorescence quenching. One-dimensional diffusion model was applied to obtain long charge diffusion distances in thick films, which is similar to 1.7 mu m for electrons and up to similar to 6.3 mu m for holes. Short diffusion distance of few hundreds of nanosecond was also observed in thin films. This thickness dependent charge diffusion explained the formerly reported short charge diffusion distance (similar to 100 nm) in films and resolved its confliction to thick working layer (300-500 nm) in real devices. This study presents direct support to the high performance perovskite solar cells and will benefit the devices' design.

We manufactured polarizing polymer solar cells (PSCs) utilizing a liquid crystalline polymer (i.e., pol y(2,5-bis(3-dodecylthiophen-2-yl) thieno[3,2-b] thiophene) (PBTTT)) as an electron donor material and a material that selectively absorbs polarized light. The oriented PBTTT films prepared using a self-organization process exhibited a high dichroic ratio of ca. 6.35 at the absorption peak. The polarizing PSCs based on oriented PBTTT-PC71BM photoactive layers exhibit an anisotropic photovoltaic effect under polarized illumination along the two orthogonal axes. The polarizing PSCs have a larger power conversion efficiency under parallel-polarized illumination than that of isotropic PV devices under unpolarized illumination. Based on picosecond fluorescent spectra, the parallel excitation produces a slower ground state recovery and a longer exciton lifetime than perpendicular excitation for PBTTT molecules in a uniaxially oriented arrangement. (C) 2015 Elsevier B.V. All rights reserved.

In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark. The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.