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Optical properties and charge-transfer process studies for efficient organic photovoltaic cells: ab-initio simulations

Grant number: 12/24227-1
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): May 01, 2013
Effective date (End): April 30, 2017
Field of knowledge:Physical Sciences and Mathematics - Physics
Principal Investigator:Alexandre Reily Rocha
Grantee:César Enrique Pérez Villegas
Home Institution: Instituto de Física Teórica (IFT). Universidade Estadual Paulista (UNESP). Campus de São Paulo. São Paulo , SP, Brazil
Associated scholarship(s):15/14899-0 - Exciton-phonon coupling effects on the optical properties of semiconductors: an ab-initio density functional theory approach, BE.EP.PD


At the interfaces formed by two contacted materials (donor and acceptor) interesting phenomena with a big number of applications for designing optoelectronic devices take place. This is the operating principle of organic photovoltaic cells (OPCs) which have attracted much attention due to its low-cost of fabrication and clean conversion of light. The efficiency and viability of OPCs depend strongly on tailoring and control of the interfaces at the molecular scales. Despite this current understanding and for designing more efficient devices, the role played by the charge-separation processes and the optical properties at the interfaces need to be addressed carefully. Thus, this project will use ab-initio simulations based on many-body theory approximation (GW approximation) to model one of the most important processes taking place at the interfaces of OPCs, the charge-transfer process. This process is critical to device performance and depends sensitively on the electronic and atomic structure of the interfaces such as the energy alignment of the charge transferred states. In such a sense, the project will be devoted to suggest and study improved heterojunctions based on: graphene nanoribbons, organic semiconductors and dyes. Special attention will be given to nanoribbons as an acceptor due to its transparency and unique optoelectronic properties which allow tuning their band gap through a proper design of their length, width, and edge structure. Thus, we will tailor the nanoribbons by edge functionalization, doping and tuning of the band gap, in order to explore its role over the charge transfer states and obtain improved heterojunctions.

Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
ROJAS, W. Y.; VILLEGAS, CESAR E. P.; ROCHA, A. R. Spin-orbit coupling prevents spin channel suppression of transition metal atoms on armchair graphene nanoribbons. Physical Chemistry Chemical Physics, v. 20, n. 47, p. 29826-29832, DEC 21 2018. Web of Science Citations: 2.
GARCIA-BASABE, YUNIER; ROCHA, ALEXANDRE R.; VICENTIN, FLAVIO C.; VILLEGAS, CESAR E. P.; NASCIMENTO, REGIANE; ROMANI, ERIC C.; DE OLIVEIRA, EMERSON C.; FECHINE, GUILHERMINO J. M.; LI, SHISHENG; EDA, GOKI; LARRUDE, DUNIESKYS G. Ultrafast charge transfer dynamics pathways in two-dimensional MoS2-graphene heterostructures: a core-hole clock approach. Physical Chemistry Chemical Physics, v. 19, n. 44, p. 29954-29962, NOV 28 2017. Web of Science Citations: 6.
VILLEGAS, CESAR E. P.; RODIN, A. S.; CARVALHO, ALEXANDRA; ROCHA, A. R. Two-dimensional exciton properties in monolayer semiconducting phosphorus allotropes. Physical Chemistry Chemical Physics, v. 18, n. 40, p. 27829-27836, OCT 28 2016. Web of Science Citations: 13.
VILLEGAS, CESAR E. P.; ROCHA, A. R.; MARINI, ANDREA. Electron-phonon scattering effects on electronic and optical properties of orthorhombic GeS. Physical Review B, v. 94, n. 13 OCT 19 2016. Web of Science Citations: 3.
VILLEGAS, CESAR E. P.; ROCHA, A. R.; MARINI, ANDREA. Anomalous Temperature Dependence of the Band Gap in Black Phosphorus. Nano Letters, v. 16, n. 8, p. 5095-5101, AUG 2016. Web of Science Citations: 27.
RIBEIRO, H. B.; VILLEGAS, C. E. P.; BAHAMON, D. A.; MURACA, D.; CASTRO NETO, A. H.; DE SOUZA, E. A. T.; ROCHA, A. R.; PIMENTA, M. A.; DE MATOS, C. J. S. Edge phonons in black phosphorus. NATURE COMMUNICATIONS, v. 7, JUL 2016. Web of Science Citations: 23.

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