title: Size of the Organic Cation Tunes the Band Gap of Colloidal Organolead Bromide Perovskite Nanocrystals.
abstract: A few approaches have been employed to tune the band gap of colloidal organic-inorganic trihalide perovskites (OTPs) nanocrystals by changing the halide anion. However, to date, there is no report of electronic structure tuning of perovskite NCs upon changing the organic cation. We report here, for the first time, the room temperature colloidal synthesis of (EA)x(MA)1-xPbBr3 nanocrystals (NCs) (where, x varies between 0 and 1) to tune the band gap of hybrid organic-inorganic lead perovskite NCs from 2.38 to 2.94 eV by varying the ratio of ethylammonium (EA) and methylammonium (MA) cations. The tuning of band gap is confirmed by electronic structure calculations within density functional theory, which explains the increase in the band gap upon going toward larger "A" site cations in APbBr3 NCs. The photoluminescence quantum yield (PLQY) of these NCs lies between 5% to 85% and the average lifetime falls in the range 1.4 to 215 ns. A mixture of MA cations and its higher analog EA cations provide a versatile tool to tune the structural as well as optoelectronic properties of perovskite NCs.
authors: Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
authors: Mona
authors: M
authors: Mittal
authors: Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
authors: Atanu
authors: A
authors: Jana
authors: Department of Condensed Matter Physics and Materials Science, S. N. Bose National Centre for Basic Sciences , JD Block, Sector III, Salt Lake, Kolkata 700106, India.
authors: Sagar
authors: S
authors: Sarkar
authors: Department of Condensed Matter Physics and Materials Science, S. N. Bose National Centre for Basic Sciences , JD Block, Sector III, Salt Lake, Kolkata 700106, India.
authors: Priya
authors: P
authors: Mahadevan
authors: Department of Chemistry, Indian Institute of Technology Delhi , Hauz Khas, New Delhi 110016, India.
authors: Sameer
authors: S
authors: Sapra