Search

One of the most crucial considerations for practical applications of organic photovoltaics (OPV) is the stability under sunlight irradiation. It is necessary to translate the small device stability to the module level. Herein, the photostability of the OPV module with three cells connected in series with a total effective area of 10.8 cm2 is presented. The stability of the OPV module is studied under continuous irradiation by a UV light‐emitting diode (LED) with integrated UV intensity the same as AM1.5 solar irradiations. As a result, the OPV module achieves good stability under UV light with a half‐lifetime of about 1300 h without a UV filter. The lifetime is similar to the small device with the same materials. The series resistance and the encapsulation must be optimized simultaneously. The suitable metal of the external electrode greatly improves the OPV module's performance. In addition, the UV stability of the normal structure is shown to be better than the inverted structure because of the photoinstability of the ZnO layer. Moreover, the UV stability of semitransparent OPV modules is shown to be‐ similar to the opaque ones. [ABSTRACT FROM AUTHOR]

The thyroid biokinetic model of radioactive I-131 was re-evaluated using a refined nine-compartmental model and applied to twelve thyroid cancer patients. In contrast to the simplified four-compartmental model regulated by the ICRP-56 report, the revised model included nine compartments specified in the ICRP-128 report, namely, oral, stomach, body fluid, thyroid, whole body, liver, kidney, bladder, and remainder (i.e., the whole body minus kidney and bladder). A self-developed program run in MATLAB was designed to solve the nine first-order simultaneous linear differential equations. The model was realized in standard and simplified versions. The latter neglected two feedback paths (body fluid to oral, i31, and kidney to the whole body, i87) to reduce computations. Accordingly, the biological half-lives for the major compartments (thyroid and body fluid + whole body) were 36.00 ± 15.01, 15.04 ± 5.63, 34.33 ± 15.42, and 14.83 ± 5.91 of standard and simplified version. The correlations between theoretical and empirical data for each patient were quantified by the dimensionless AT (agreement) index and, the ATtot index integrated each individual AT of a specific organ of one patient. Since small AT values indicated a closer correlation, the obtained range of ATtot (0.048 ± 0.019) proved the standard model’s reliability and high accuracy, while the simplified one yielded slightly higher ATtot (0.058 ± 0.023). The detailed outcomes among various compartments of twelve patients were calculated and compared with other researchers’ work. The correlation results on radioactive I-131 evolution in thyroid cancer patients’ bodies are instrumental in viewpoint of radioactive protection of patients and radiological personnel.

Circularly polarized luminescence (CPL) materials are promising candidates for future display technology. However, such highly efficient emitters suffer from the issues of difficult chiral separation and low photoluminescence quantum yield (PLQY). In this work, the chiral 4,4′‐biphenanthrene‐3,3′‐diol (BIPOL) unit was introduced into a thermally activated delayed fluorescence (TADF) framework for the first time. We presented two series of enantiomers, R/S‐o‐DCzBPNCN and R/S‐p‐DCzBPNCN, and the synthesis of enantiopure BIPOL can be prepared via normal column chromatography. Notably, o‐DCzBPNCN showed narrow singlet‐triplet gap of 0.05 eV, efficient TADF, and high PLQYs of 82 % in doped films. In addition, R/S‐o‐DCzBPNCN exhibited high luminescence dissymmetry factor (gPL) values of −1.94×10−2/+1.91×10−2 in doped films. The strategy of BIPOL introduction offers a new approach to organic emitters with stereospecific synthesis, TADF, and chiroptical properties. [ABSTRACT FROM AUTHOR]

The solution‐processed electrode is key to the full‐solution‐processed organic solar cells (OSCs). Silver nanowires (AgNWs) are considered as an attractive solution‐processed electrode due to their low sheet resistance and high transmittance. However, the traditional "line‐plane" contact between AgNWs and the interface buffer layer is insufficient, resulting in the low performance of full‐solution‐processed OSCs. Herein, a bulk contact structure is reported between AgNWs and interface, formed by inserting the interface layer material, such as HMoOx (hydrogen molybdenum bronze) into the AgNWs networks. The extra HMoOx can be connected with the bottom interface buffer layer, forming a longitudinal network, and wrapping the AgNWs in the longitudinal interfacial layer. This bulk contact electrode‐interface structure increases the area of AgNWs/interface layers, promoting charge transfer and collection. Besides, the top‐injected method can enable the formation of a water‐based ink film on the top of the organic layer, as well as avoid solvent erosion between AgNWs and the interface layer. Based on the bulk contact electrode‐interface structure, this work realized high performance of 12.27% and 9.54% for 0.09 cm2 small‐area device and 10.8 cm2 full‐solution‐processed semitransparent mini‐module. These results provide a new idea for full‐solution‐processed OSCs preparation. [ABSTRACT FROM AUTHOR]

CsPbBr3 quantum dots with various diameters around the Bohr exciton radius and emission wavelengths between 460 nm to 520 nm were prepared. Quantum dots with diameters of 4–13 nm were characterized via their absorption spectra, photoluminescence spectra, X-ray diffraction patterns, and time-resolved photoluminescence. Binary mixture solutions and composite films composed of blue and green CsPbBr3 quantum dots showed two emission peaks without anion-exchange issues. A solution of red CdSe quantum dots was added to the sky-blue binary mixture solution to form a ternary mixture solution with white emission. Three clear emission peaks were observed, and the CIE chromaticity coordinates (0.33, 0.31) were obtained. A QD–polymer composite film with white emission was prepared and stacked on a UV LED to demonstrate white LEDs. Besides, white LEDs with a single emissive layer were prepared from the ternary mixture solution. Three emission peaks and CIE coordinates of (0.34, 0.33) were obtained. [ABSTRACT FROM AUTHOR]

The introduction of biuret hydrogen-bonding sites onto chiral binaphthalene-based chromophores was investigated as a route to sub-micron-sized, vesicle-like aggregates endowed with chiroptical properties. The synthesis was conducted from the corresponding chiral 4,4′-dibromo-1,1′-bis(2-naphthol) via Suzuki–Miyaura coupling to afford luminescent chromophores whose emission spectrum could be tuned from blue to yellow-green through extension of the conjugation. For all compounds, the spontaneous formation of hollow spheres with a diameter of ca. 200–800 nm was evidenced by scanning electron microscopy, along with strong asymmetry in the circularly polarized absorption spectra. For some compounds, the emission also displayed circular polarization with values of glum = ca. 10–3 which could be increased upon aggregation. [ABSTRACT FROM AUTHOR]

The ultraviolet (UV) part in the sunlight is known to cause most damage to organic photovoltaics (OPV). UV filters therefore can improve stability. The lifetime of the UV‐filtered OPV is determined by visible light. Herein, visible sunlight is divided into several bands and modeled by light‐emitting diodes to study the stability of ternary OPV. Poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione)] (PM6) is used as the donor. 2,2′‐((2Z,2′Z)‐((12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2",3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2‐g]thieno[2′,3′:4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (Y6) is used as the acceptor. Another polymer is added as the second donor to improve the stability. As expected, the deep and light blue bands dominate the decay under visible light. After about 1200 h of blue irradiation, the devices enter a relatively stable state up to 3000 h of tracking, in sharp contrast to the continuous decay under UV. No chemical reaction is observed under blue light. Years of outdoor lifetime for nonfullerene OPV are projected with the UV filter. [ABSTRACT FROM AUTHOR]

The ultraviolet (UV) radiation in the solar spectrum causes most of the decay under sunlight for solar cells based on organic photovoltaics (OPV). One‐year outdoor lifetime still remains challenging for OPV. The lifetime of 2000 h under continuous laboratory light corresponds to a 1 year outdoor lifetime. Herein, the stability of the OPVs is studied under continuous irradiation by a UV light emitting diode of 365 nm with a long tracking time. The intensity of 50 W m−2 is the same as the sunlight UV. The compositions of the active layer and cathode interfacial layer are sensitive to UV irradiation. In general, ternary devices have better UV stability than binary devices. In particular, a good stability is achieved for the ternary device based on the high‐performance blend with poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl‐3‐fluoro)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b']dithiophene))‐alt‐(5,5‐(1',3'‐di‐2‐thienyl‐5',7'‐bis(2‐ethylhexyl)benzo[1',2'‐c:4',5'‐c']dithiophene‐4,8‐dione)] (PM6) as the donor. The acceptor is 2,2'‐((2Z,2'Z)‐((12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2‐g]thieno[2',3':4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (Y6). The fullerene derivative [6,6]‐phenyl C71‐butyric acid methyl ester (PC71BM) is added as the second acceptor, whereas a polymer poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b']dithiophene))‐co‐(1,3‐di(5‐thiophene‐2‐yl)‐5,7‐bis(2‐ethylhexyl)benzo[1,2‐c:4,5‐c']dithiophene‐4,8‐dione)] (PBDB‐T) is added as the second donor. For the PM6:Y6 ternary device, the UV half lifetime is 1750 h, which is close to the 2000 h target set by the outdoor of a 1 year lifetime. [ABSTRACT FROM AUTHOR]

Through the incorporation of various halogen‐substituted chiral organic cations, the effects of chiral molecules on the chiroptical properties of hybrid organic–inorganic perovskites (HOIPs) are investigated. Among them, the HOIP having a Cl‐substituted chiral cation exhibits the highest circular dichroism (CD) and circular polarized luminescence (CPL) intensities, indicating the existence of the largest rotatory strength, whereas the F‐substituted HIOP shows the weakest intensities. The observed modulation can be correlated to the varied magnetic transition dipole of HOIPs, which is sensitive to the d‐spacing between inorganic layers and the halogen–halogen interaction between organic cations and the inorganic sheets. These counteracting effects meet the optimal CD and CPL intensity with chlorine substitution, rendering the rotatory strength of HOIPs arranged in the order of (ClMBA)2PbI4>(BrMBA)2PbI4>(IMBA)2PbI4>(MBA)2PbI4>(FMBA)2PbI4. [ABSTRACT FROM AUTHOR]

In this study, lead‐free perovskite CsSn(IxBr1−x)3 films with photoluminescence emission wavelengths from 677 to 887 nm are prepared. The influence of air exposure on their characteristics is also investigated. It is found that CsSnI3 can be transformed to Cs2SnI6 upon increasing the air exposure time. The decomposition and oxidation mechanisms are confirmed by the X‐ray diffraction pattern due to the presence of CsI peak. It is observed that devices based on the CsSn(IxBr1−x)3 film with increased Br− ratio and the CsSnI3 film with prolonged air exposure time show inferior performance. These results are mainly attributed to the highest occupied molecular orbital levels of CsSn(IxBr1−x)3 and Cs2SnI6. Defect density of state and binding energy of these materials are also investigated and reported in this study. [ABSTRACT FROM AUTHOR]

Perovskite white light-emitting diodes were realized by using a mixture of sky-blue MAPb(Br0.6Cl0.4)3 and orange-red rhodamine 6G as the emissive layer. The influences of rhodamine 6G on the properties of perovskite films were investigated using absorption spectroscopy, steady-state and time-resolved photoluminescence spectroscopy, X-ray diffraction, scanning electron microscopy and confocal laser-scanning fluorescence microscopy. The emissions from MAPb(Br0.6Cl0.4)3 and rhodamine 6G were mixed to realize white light. The CIE chromaticity coordinates of (0.33, 0.4) and (0.36, 0.40) were obtained for devices with 2 wt% and 3 wt% rhodamine 6G, respectively. [ABSTRACT FROM AUTHOR]

A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method. [ABSTRACT FROM AUTHOR]

The microscopic states and performance of organic solar cell are investigated theoretically to explore the effect of the carrier mobility. With Ohmic contacts between the semiconductor and the metal electrodes there are two origins of carriers in the semiconductor: the photocarriers generated by photon absorption and the dark carriers diffused from the electrodes. The power efficiency of the solar cell is limited by the recombination of a carrier with either the photocarrier or a dark carrier. Near the short-circuit condition the photocarrier recombination in the semiconductor bulk decreases as the mobility increases. Near the open-circuit condition the dark carrier recombination increases with the mobility. These two opposite effects balance with one another, resulting in an optimal mobility about 10-2 cm2/V s which gives the highest power conversion efficiency. The balance of the electron and hole mobilities are not necessary to maintain the optimal efficiency also because of the balance of the photocarrier and dark carrier recombination. The efficiency remains about the same as one carrier mobility is fixed at 10-2 cm2/V s while the other one varies from 10-1 to 10-3 cm2/V s. For solar cell with a Schottky barrier between the semiconductor and the metal electrode there is no dark carrier recombination. The efficiency therefore always increases with the mobility. [ABSTRACT FROM AUTHOR]

The electrical current leakage and stability are studied for solution OLED with areas of 4.45 mm2, 3×3.2 cm2, and 6×11.5 cm2. All organic layers are deposited by blade coating and initial current leaking defects can be avoided by careful control of the coating conditions. The detrimental burning point caused by a local current short developed after long‐time operation can be avoided by reducing the operation voltage using ternary mixed host. Furthermore, the crystallization defect is reduced by the ternary host. For orange device the binary host is good enough. For area as large as 6 × 11.5 cm2 the OLED no burning point after an operation over 1600 hours. [ABSTRACT FROM AUTHOR]

The instability of the organic light‐emitting diodes (OLEDs) during operation can be attributed to the existence of point defects on the organic layers. In this work, the effect of mixed‐host emissive layer and the thermal annealing treatment were investigated to eliminate defects and to boost the device performance. The mixed‐host system includes 4,4′,4′′‐tri (9‐carbazoyl) triphenylamine (TCTA) and 2,7‐bis(diphenylphosphoryl)‐9, 9′‐spirobi[fluorene] (SPPO13). The mixed‐host emissive layer with thermal annealing treatment showed low roughness and few pinholes, and the devices fabricated from this emissive layer exhibited high efficiencies, high stabilities, and long lifetimes. The red and orange‐red OLEDs exhibited efficiencies of 13.9 cd/A and 24.35 cd/A, respectively. The longest half‐lifetime (L0=500 cd/m2) of the red and orange‐red OLEDs were 158 h and 180 h, respectively. Efforts were made to solve problems in large‐area coating and to reduce the number of defects on in organic layer. Large‐active‐area (active area=3 cm×4 cm) red phosphorescent OLEDs (PhOLEDs) devices were realized with very high current efficiency up to 9 cd/A. [ABSTRACT FROM AUTHOR]

Perovskite light-emitting diodes (LEDs) are attractive because of their high efficiency and narrow emission. However, most of the current research on perovskite LEDs with primary color emission is focused on performance enhancement. Only a few studies focused on perovskite white LEDs. Here, we realized a perovskite white light-emitting diode with a single emissive layer by mixing the emission from a sky-blue perovskite material and an orange-near infrared (NIR) organic compound. Compounds with orange-NIR emission are synthesized and the influence of the compounds on the perovskite films is investigated by absorption and photoluminescence spectroscopy, X-ray diffraction, scanning electron microscopy and confocal laser-scanning fluorescence microscopy. Perovskite white LEDs were realized with CIE chromaticity coordinates of (0.3, 0.49), which are approaching the ideal pure white emission coordinates (0.33, 0.33). [ABSTRACT FROM AUTHOR]

In this study, an efficient and stable large‐area blade‐coated organic solar cell (OSC) module with an active area of 216 cm2 (16 elementary cells connected in series) is demonstrated by combining appropriate thermal annealing treatment with the use of 4,4′‐(((methyl(4‐sulphonatobutyl)ammonio)bis(propane‐3,1‐diyl))bis(dimethyl‐ammoniumdiyl))bis‐(butane‐1‐sulfonate) (MSAPBS) as the cathode interfacial layer. For the opaque device using poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PBDTTT‐EFT (PTB7‐Th)):[6,6]‐phenyl C71‐butyric acid methyl ester (PC71BM) blend film as the active layer, the power conversion efficiency (PCE) of 5.6% is achieved under AM 1.5G solar light illumination. Very encouragingly, our strategy can be applicable for semitransparent OSCs, and a remarkable PCE up to 4.5% is observed. To the best of our knowledge, the PCE of 5.6% for opaque device and 4.5% for semitransparent device represent the highest PCE ever reported for OSCs with the active area exceeding 100 cm2. The devices also show an impressive stability under outdoor environment, where the efficiency decay is less than 30% for 60 days. Our findings can pave the way toward the development of organic solar cell modules with high performance and long‐term stability. The large‐area modules with active area = 216 cm2 by blade coating technique exhibits an efficiency of 5.6%. [ABSTRACT FROM AUTHOR]

Abstract: Interfacial engineering plays an important role in determining the performance and stability of polymer solar cells (PSCs). In this study, thermally stable highly efficient PSCs are fabricated by incorporating a solution‐processed cathode interfacial layer (CIL), including 4,4′‐({[methyl(4‐sulfonatobutyl)ammonio]bis(propane‐3,1‐diyl)}bis(dimethylammoniumdiyl))bis(butane‐1‐sulfonate) (MSAPBS) and polyethylenimine (PEI). For PSCs based on blends of poly{4,8‐bis[5‐(2‐ethylhexyl)thiophen‐2‐yl]benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐[4‐(2‐ethylhexyl)‐3fluorothieno[3,4‐b]thiophene‐2‐carboxylate‐2,6‐diyl]} (PBDTTT‐EFT) and [6,6]‐phenyl C71‐butyric acid methyl ester (PC71BM), the maximum power conversion efficiency (PCE) of inverted PSCs reaches 8.1 % and 7.2 % for MSAPBS and PEI CILs, respectively. The inverted PEI devices exhibit remarkable stability (lifetime >6000 h) under accelerated thermal aging (at 80 °C in ambient environment), which is much superior to that of the device with commonly used LiF CIL (lifetime≈33 h). This stability represents the best result reported for PSCs. The promising results based on this strategy can stimulate further work on the development of novel CILs for PSCs and pave the way towards the realization of commercially viable PSCs with high performance and long‐term stability. [ABSTRACT FROM AUTHOR]

Here, we report that long-term stable and efficient organic solar cells (OSCs) can be obtained through the following strategies: i) combination of rapid-drying blade-coating deposition with an appropriate thermal annealing treatment to obtain an optimized morphology of the active layer; ii) insertion of interfacial layers to optimize the interfacial properties. The resulting devices based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl- alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate-2,6-diyl)] (PBDTTT-EFT):[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) blend as the active layer exhibits a power conversion efficiency (PCE) up to 9.57 %, which represents the highest efficiency ever reported for blade-coated OSCs. Importantly, the conventional structure devices based on poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) blend can retain approximately 65 % of their initial PCE for almost 2 years under operating conditions, which is the best result ever reported for long-term stable OSCs under operational conditions. More encouragingly, long-term stable large-area OSCs (active area=216 cm2) based on P3HT:PCBM blend are also demonstrated. Our findings represent an important step toward the development of large-area OSCs with high performance and long-term stability. [ABSTRACT FROM AUTHOR]