Stability of MAPbI perovskite grown on planar and mesoporous electron-selective contact by inverse temperature crystallization.

Single crystalline perovskite solar cells (PSC) are promising for their inherent stability due to the absence of grain boundaries. While the development of single crystals of perovskite with enhanced optoelectronic properties is known, studies on the growth, device performance and understanding of the intrinsic stability of single crystalline perovskite thin film solar cell devices fabricated on electron selective contacts are scarcely explored. In this work, we examine the impact of mesoporous TiO (m-TiO) and planar TiO (p-TiO) on the growth of single crystalline-methyl ammonium lead iodide (SC-MAPbI) film, PSC device performance and film stability under harsh weather conditions (T ∼ 85 °C and RH ∼ 85%).

Effect of solvent on the electronic absorption spectral properties of some mixed β-octasubstituted Zn(II)-tetraphenylporphyrins.

A series of mixed β-octasubstituted Zn(II)-porphyrins, 2,3,12,13-tetra(chloro/cyano/methyl)-5,7,8,10,15,17,18,20-octaphenylporphinato zinc(II), ZnTPP(Ph)X (X=CN, Cl and CH) have been examined by electronic absorption spectroscopy in various solvents. These Zn(II)-porphyrins exhibited varying degree of red-shift of absorption bands as high as 20-30nm in 'B' band and 50-60nm in longest wavelength band, 'Q(0,0)' band in polar solvents relative to that found in nonpolar solvents. The red-shift of B and Q(0,0) bands showed an unusual trend, ZnTPP(Ph)(CN)>ZnTPP(Ph)(CH)>ZnTPP(Ph)Cl but fails to follow an anticipated anodic shift in first porphyrin ring oxidation (vs Ag/AgCl) potential: ZnTPP(Ph)(CN) (1.

Planar and nonplanar free-base tetraarylporphyrins: β-pyrrole substituents and geometric effects on electrochemistry, spectroelectrochemistry, and protonation/deprotonation reactions in nonaqueous media.

A series of planar and nonplanar free-base β-pyrrole substituted meso-tetraarylporphyrins were characterized by electrochemistry, spectroelectrochemistry, and protonation or deprotonation reactions in neutral, acidic, and basic solutions of CH2 Cl2 . The neutral compounds are represented as H2 (P), in which P represents a porphyrin dianion with one of several different sets of electron-withdrawing or -donating substituents at the messo and/or β-pyrrole positions of the macrocycle. The conversion of H2 (P) to [H4 (P)](2+) in CH2 Cl2 was accomplished by titration of the neutral porphyrin with trifluoroacetic acid (TFA) while the progress of the protonation was monitored by UV/Vis spectroscopy, which was also used to calculate logβ2 for proton addition to the core nitrogen atoms of the macrocycle.

Mixed β-pyrrole substituted meso-tetraphenylporphyrins and their metal complexes: optical nonlinearity using degenerate four wave mixing technique.

We have investigated the roles of structural modification and polar effects in the optical nonlinearities of a series of selectively mixed β-pyrrole functionalized tetraphenylporphyrin, MTPP(CHO)(R)2 (R = H, Br, 2-thienyl, phenyl (Ph), phenylethynyl (PE) compounds and their metal (Cu(II), Zn(II)) complexes in toluene. In the present study, we have used phase conjugation geometry of the four wave mixing process to measure the third order nonlinear susceptibility (χ(3)) and the second order hyperpolarizabilty ((γ)) with picosecond laser pulse excitation at 532 nm. An increase in the values of χ(3) and (γ) for electron-withdrawing groups was observed whereas an opposite trend was noticed for the electron-donating groups at the β-pyrrole positions.