Zero-dimensional (CH3NH3)3Bi2I9 perovskite for optoelectronic applications.

We present the preparation and characterization of solution processed lead free films of zero-dimensional methylammonium iodo bismuthate (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite. Structural characterization reveals the formation of hexagonal micro-crystals with preferred growth orientation along the c -axis. The material exhibits a wide band gap of 2.9 eV and upon optical excitation the photoluminescence emission is observed at 1.65 eV (751 nm). Photoelectron spectroscopy confirms the stoichiometry of the (CH 3 NH 3 ) 3 Bi 2 I 9 perovskite and yields an ionization energy of 6.24 eV, while Raman spectra confirm the vibrational modes of the bioctahedral inorganic anion framework (Bi 2 I 9 ) 3− in the low wavenumber regime (<200 cm −1 ) regime. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) are employed to evaluate the experimental results. We apply this novel bismuth-based hybrid perovskite in proof of principle simple heterojunction solar cell devices, which yield power conversion efficiencies of ~0.1%. Further enhancement is expected once the film morphology and device stack are optimized. [ABSTRACT FROM AUTHOR]