Banca de DEFESA: JESÚS CAMILO DÍAZ OLIVELLA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : JESÚS CAMILO DÍAZ OLIVELLA
Data: 13/05/2026
HORA: 14:00
LOCAL: Online
TÍTULO:

Molecular engineering to tune the

energy gap of two‐dimensional

perovskites.

PÁGINAS: 98
RESUMO:

Quasi-two-dimensional halide perovskites are promising candidates for optoelectronic

applications, yet the organic spacer layer that separates the inorganic slabs typically

confines charge carriers within a Type I alignment, limiting out-of-plane transport.

Transforming the spacer from a passive barrier into an active electronic component

requires engineering a Type II (staggered) band alignment between the spacer’s frontier

molecular orbitals and the perovskite band edges—a design problem constrained

by the scarcity of organic molecules with sufficiently deep LUMO levels.

This thesis addresses this challenge through three contributions. First, the q2DMaterials

software framework is developed, providing a layer-sequence-driven construction

strategy, all 15 standard Glazer tilt systems, and a graph-based structural

ontology for systematic featurization of quasi-2D perovskites. Second, the framework

is applied to generate and analyze a dataset of 216 Dion–Jacobson perovskites, systematically

varying the halide (Cl, Br, I), inorganic slab thickness (n = 1, 2, 3), and organic

spacer (24 diammonium cations spanning linear, branched, cyclic, and aromatic families).

Structural analysis of the DFT-optimized structures shows that the halide ionic

radius determines the primary strain-relief pathway upon spacer incorporation: chloride

promotes cooperative octahedral tilts, bromide predominantly undergoes internal

distortions, and iodide can support a mixture of both mechanisms. Third, density

functional theory calculations (r2SCAN+rVV10) combined with LOBSTER-projected

densities of states reveal that the same ordering—halide composition > slab thickness

> organic spacer—also controls the electronic structure, confirming that band-edge

energies are directly governed by the underlying geometric distortions. Screening all

216 candidates pinpoints MAPbBr3 (n = 1) paired with a benzene-based diammonium

spacer as the most promising Type II aligned system, exhibiting VBM–HOMO

and CBM–LUMO offsets of about 1 eV. Aromatic π interactions reduce the spacer’s

HOMO–LUMO gap, partially mitigating the LUMO bottleneck. Collectively, these

findings identify aromatic spacers as the most promising molecular design motif and

deliver a quantitative structure–electronic landscape to steer further band-alignment

optimization in Dion–Jacobson perovskites.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - ***.789.370-** - GUSTAVO MARTINI DALPIAN - USP
Membro Titular - Examinador(a) Interno ao Programa - 2605463 - JOSE ANTONIO SOUZA
Membro Titular - Examinador(a) Externo à Instituição - LUANA SUCUPIRA PEDROZA - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1734908 - FABIO FURLAN FERREIRA
Membro Suplente - Examinador(a) Interno ao Programa - 2249395 - THIAGO BRANQUINHO DE QUEIROZ
Membro Suplente - Examinador(a) Externo à Instituição - ALEXANDRE REILY ROCHA - UNESP