Perovskite CIGS Tandem Solar Cells From Certified 24.2 toward 30 and Beyond

We demonstrate a monolithic perovskite CIGS tandem solar cell with a certified power conversion efficiency PCE of 24.2 . The tandem solar cell still exhibits photocurrent mismatch between the subcells; thus optical simulations are used to determine the optimal device stack. Results reveal a high optical potential with the optimized device reaching a short circuit current density of 19.9 mA cm 2 and 32 PCE based on semiempirical material properties. To evaluate its energy yield, we first determine the CIGS temperature coefficient, which is at amp; 8722;0.38 K 1 notably higher than the one from the perovskite subcell amp; 8722;0.22 K 1 , favoring perovskite in the field operation at elevated cell temperatures. Both single junction cells, however, are significantly outperformed by the combined tandem device. The enhancement in energy output is more than 50 in the case of CIGS single junction device. The results demonstrate the high potential of perovskite CIGS tandem solar cells, for which we describe optical guidelines toward 30 PC

Photoinduced optical functionalism of branched azophenylcarbazoles in molecular glass matrices

A new guest-host composition of 3-(4-nitrophenyl)azo-9-(2-ethyl)hexyl-2-(2- ethyl) hexyloxycarbazole as chromophore and 2,2-bis{4-[2-hydroxy-9-(carbazol-9- yl)-5- (carbazol-9-methyl)-4,7-dioxanonyloxy]phenyl}propane (molecular glass) as host for all-optical poling application was developed and investigated. A comparison between molecular glass and commonly used bisphenol Z polycarbonate as host showed a slightly better ability for the molecular glass to keep the azophenylcarbazole molecules oriented. Erasure while reading the non-centrosymmetry created is demonstrated and explained. Using an adopted model orientational diffusion coefficient, lifetime of cis isomer and probabilities of redistribution were evaluated. © Taylor & Francis Group, LLC

Photoinduced orientational dynamics of azophenylcarbazole molecules in polycarbonate

The synthesis and new optical features of four azophenylcarbazoles are described. All-optical poling of the azophenylcarbazoles with different donor groups was investigated. The highest optical poling efficiency (χ( 2)≃0.72pm/V) was measured for relative larger molecules (branched). Parameters describing mobility of the azophenylcarbazoles (orientational diffusion coefficient vary from 2.2 × 10-5 s-1 to 8 × 10-5 s-1) were extracted using an adopted model. Photoinduced erasure while reading the poled media turned out to be more pronounced for less developed structures (less branched donor). Different polymer materials were investigated as the host matrix for the most interesting azophenylcarbazole molecule. © 2011 Elsevier Ltd. All rights reserved

Electrochemical cross-linking of carbazole derivatives: a new route for bulk heterojunction based on semi-interpenetrating polymer networks

Electrochemical behaviors of different pendant carbazole based oligomers have been studied for the realization of electroactive tridimensional structures. 3-substitution by hydrazone functional groups onto the pendant carbazole moieties increases the electron donor properties of the electroactive units. Electrochemical oxidation of thin films of the oligomer precursors deposited onto electrode ensures the formation of a cross-linked structure by in situ anodic coupling with the formation of biscarbazole redox sites. When the electrochemical cross-linking of the oligomers is realized in the presence of the electron acceptor polyimide (perylene based), we form a semi-interpenetrating polymer network (semi-IPN) coated as a thin layer. The electrochemical behavior of the semi-IPN shows two reversible oxidations and two reversible reduction peaks indicating respectively the p-doping of the biscarbazole entity and the n-doping of the perylene one. The presence of hydrazone substituents modifies the electron donor properties of the semi-IPN and should influence the electron transfer properties from biscarbazole to perylene units in bulk heterojunction solar cells

Arylmethylene-1,3-indandione based molecular glasses: Third order optical non-linearity

The synthesis and new optical features of three indan-1,3-dione class structures is reported. The simple arylmethylene-1,3-indandione structure 2-(4-diethylaminobenzylidene)indan-1,3-dione was used to design two linked structures: 1,3-bis-{3-hydroxy-4-[4-diethylamino-1-(1,3-dioxoindan-2- ylmethylene)benzen-3-yloxy]-1-thiabuthyl}benzene and 4,4′-bis-{{3-hydroxy- 4-[4-diethylamino-1-(1,3-dioxoindan-2-ylmethylene)benzen-3-yloxy]-1-thiabutyl} phenyl}sulfide. In contrast to the simple compound, which readily crystallized, the linked derivatives remained in an amorphous phase and are considered as molecular glasses with respective glass transition temperatures 88 and 100°C. For non-linear optical investigations samples were prepared as a guest-host system in polycarbonate matrix (10%). The Maker-fringe technique was used to investigate the third harmonic generation at a wavelength of 355 nm (YAG laser). Third-order non-linear susceptibility χ (3) values were extracted 5.75·10 -21 m 2 V -2, 8.60·10 -21 m 2 V -2, 16.85·10 -21 m 2 V -2 for these respective indandiones while modeling the experimental results. To evaluate the susceptibility of the indan-1,3-dione derivatives third harmonic generation a comparative experiment for a reference azodye in polycarbonate was performed. The results show an important feature - higher molecular second order hyperpolarizability for the linked structures. NMR, MS, IR, UV-VIS, XRD and elemental analysis were used to structurally characterize the new compounds and ellipsometry was applied to interpret the non-linear optical results. © 2012 Elsevier Ltd. All rights reserved