Advances of optoelectronic devices based on methylammonium lead halide perovskites depend on understanding the role of excitons, whether it is marginal as in inorganic semiconductors, or crucial, like in organics. However, a consensus on the exciton binding energy and its temperature dependence is still lacking, even for widely studied methylammonium lead iodide and bromide materials (MAPbI3, MAPbBr3). Here we determine the exciton binding energy based on an f-sum rule for integrated UV-vis absorption spectra, circumventing the pitfalls of least-squares fitting procedures. In the temperature range 80-300 K, we find that the exciton binding energy in MAPbBr3 is EB = (60 ± 3) meV, independent of temperature; for MAPbI3, in the orthorhombic phase (below 140 K) EB = (34 ± 3) meV, while in the tetragonal phase the binding energy softens to 29 meV at 170 K and stays constant up to 300 K. Implications of binding energy values on solar cell and LED workings are discussed.

Absorption f-sum rule for the exciton binding energy in methylammonium lead halide perovskites

SESTU, NICOLA
Primo
;
CADELANO, MICHELE;SARRITZU, VALERIO;CHEN, FEIPENG;MARONGIU, DANIELA;MAINAS, MARINA;QUOCHI, FRANCESCO;SABA, MICHELE
;
MURA, ANTONIO ANDREA;BONGIOVANNI, GIOVANNI LUIGI CARLO
Ultimo
2015

Abstract

Advances of optoelectronic devices based on methylammonium lead halide perovskites depend on understanding the role of excitons, whether it is marginal as in inorganic semiconductors, or crucial, like in organics. However, a consensus on the exciton binding energy and its temperature dependence is still lacking, even for widely studied methylammonium lead iodide and bromide materials (MAPbI3, MAPbBr3). Here we determine the exciton binding energy based on an f-sum rule for integrated UV-vis absorption spectra, circumventing the pitfalls of least-squares fitting procedures. In the temperature range 80-300 K, we find that the exciton binding energy in MAPbBr3 is EB = (60 ± 3) meV, independent of temperature; for MAPbI3, in the orthorhombic phase (below 140 K) EB = (34 ± 3) meV, while in the tetragonal phase the binding energy softens to 29 meV at 170 K and stays constant up to 300 K. Implications of binding energy values on solar cell and LED workings are discussed.
UV−vis absorption; Exciton binding energy; Methylammonium lead halide perovskites; Optical constants; Optical properties
File in questo prodotto:
File Dimensione Formato  
Sestu et al._The Journal of Physical Chemistry Letters_2015(2).pdf

Solo gestori archivio

Tipologia: versione editoriale
Dimensione 2.06 MB
Formato Adobe PDF
2.06 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11584/134166
Citazioni
  • ???jsp.display-item.citation.pmc??? 12
  • Scopus 124
  • ???jsp.display-item.citation.isi??? 124
social impact