We synthesized and characterized methylammonium (MA) mixed tri-halide tin perovskites (MASnIBr Cl ) for carbon-based mesoscopic solar cells free of lead and hole-transporting layers. Varied SnCl /SnBr ratios yielded tin perovskites with three halides (I, Br, and Cl) co-crystallized inside the tin-perovskite. When the SnCl proportion was ≥50 % (x≥1), phase separation occurred to give MASnI Br and MASnCl Br in the stoichiometric proportions of their precursors, confirmed by XRD. A device with MASnIBr Cl (SnCl =10 %) showed the best photovoltaic performance: J =14.0 mA cm , V =380 mV, FF=0.573, and PCE=3.1 %, and long-term stability. Electrochemical impedance spectra (EIS) show superior charge recombination and dielectric relaxation properties for the MASnIBr Cl cell. Transient PL decays showed the intrinsic problem of tin-based perovskites with average lifetimes less than 100 ps.

Fabrication of mesoporous carbon-based perovskite solar cells via slow crystallization using NMP solvent attained a great device efficiency of 15% with preferred orientation of the crystals at the (004) facet.

Two fullerene derivatives with styryl and oxetane cross-linking groups served as interfacial materials to modify an electron-transporting layer (ETL) of TiO, doped with Au nanoparticles, processed under low-temperature conditions to improve the performance of perovskite solar cells (PSC). The cross-linkable [6,6]-phenyl-C-butyric styryl dendron ester was produced via thermal treatment at 160 °C for 20 min, whereas the cross-linkable [6,6]-phenyl-C-butyric oxetane dendron ester (C-PCBOD) was obtained via UV-curing treatment for 45 s. Both cross-linked fullerenes can passivate surface-trap states of TiO and have also excellent surface coverage on the TiO layer shown in the corresponding atomic force microscopy images. To improve the crystallinity of perovskite, we propose a simple co-solvent method involving mixing dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a specific ratio (DMF/DMSO = 90/10). The fullerene derivative layer between the ETL and perovskite layers significantly improved electron extraction and suppressed charge recombination by decreasing the density of traps at the ETL surface. A planar PSC device was fabricated with the configuration indium tin oxide/TiO (Au)/C-PCBOD/perovskite/spiro-OMeTAD/Au to attain a power conversion efficiency (PCE) of 15.9%. The device performance was optimized with C-PCBOD as an interfacial mediate to modify the surface of the mesoporous TiO ETL; the C-PCBOD-treated device attained a significantly enhanced performance, PCE 18.3%. Electrochemical impedance spectral and photoluminescence decay measurements were carried out to understand the characteristics of electron transfer and charge recombination of the perovskite/TiO samples with and without a fullerene interfacial layer.

We synthesized and characterized methylammonium (MA) mixed tri-halide tin perovskites (MASnIBr 2Àx Cl x ) for carbon-based mesoscopic solar cells free of lead and holetransporting layers.V aried SnCl 2 /SnBr 2 ratios yielded tin perovskites with three halides (I, Br,a nd Cl) co-crystallized inside the tin-perovskite.W hen the SnCl 2 proportion was ! 50 %( x ! 1), phase separation occurred to give MAS-nI 3Ày Br y and MASnCl 3Àz Br z in the stoichiometric proportions of their precursors,c onfirmed by XRD.Ad evice with MASnIBr 1.8 Cl 0.2 (SnCl 2 = 10 %) showed the best photovoltaic performance:J SC = 14.0 mA cm À2 ,V OC = 380 mV,F F= 0.573, and PCE = 3.1 %, and long-term stability.E lectrochemical impedance spectra (EIS) show superior charge recombination and dielectric relaxation properties for the MASnIBr 1.8 Cl 0.2 cell. Transient PL decays showed the intrinsic problem of tinbased perovskites with average lifetimes less than 100 ps.