Title Interface recombination & emission applied to explain photosynthetic mechanisms for (e-, h+)...
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recombination & emission applied to explain photosynthetic mechanis charges’ separation , Denis Chaumont c , Claudia Brainer Mota a , Thiago Vasconcelos b , Frederico Dias Nunes b , o Pompelli d , Sergio Luiz Morelhao e , Anderson S. L. Gomes a of Physics, Universidade Federal de Pernambuco, Recife, Brazil. of Eletronics and Systems, Universidade Federal de Pernambuco, Recife, Brazil. oup ICB & UFR Sc. Techn. FR 2604 – Université de Bourgogne, 9 avenue A. Savary, Dijon, ology Laboratory, Universidade Federal de Pernambuco, Department of Botany, CCB, Recife artment, Universidade de Sao Paulo - Cidade Universitaria Sao Paulo Brazil Journal of Nano Science and Engineering //www.scirp.org/journal/wjnse D: 4400054 rt Information: SI-1 y staggered interface: electrical charge separation mechanism 1
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Transcript of Title Interface recombination & emission applied to explain photosynthetic mechanisms for (e-, h+)...
TitleInterface recombination & emission applied to explain photosynthetic mechanisms for (e-, h+) charges’ separation
Marco Sacilottia,c, Denis Chaumontc, Claudia Brainer Motaa, Thiago Vasconcelosb, Frederico Dias Nunesb,
Marcelo Francisco Pompellid, Sergio Luiz Morelhaoe, Anderson S. L. Gomesa
a Department of Physics, Universidade Federal de Pernambuco, Recife, Brazil. b Departament of Eletronics and Systems, Universidade Federal de Pernambuco, Recife, Brazil.c Nanoform Group ICB & UFR Sc. Techn. FR 2604 – Université de Bourgogne, 9 avenue A. Savary, Dijon, France. d Plant Physiology Laboratory, Universidade Federal de Pernambuco, Department of Botany, CCB, Recife, Brazil. e Physics Department, Universidade de Sao Paulo - Cidade Universitaria Sao Paulo Brazil
World Journal of Nano Science and Engineeringhttp://www.scirp.org/journal/wjnse Paper ID: 4400054
Support Information: SI-1
Energy staggered interface: electrical charge separation mechanism.
1
Figure SI-1-1, representing the energy staggered interface: electrical charge separation mechanism. How does the energy band bending arrive at the energetic interface? The flow of charges from one material to the nearby material creates an electronic no-equilibrium on both materials, near the interface. This electronic non-equilibrium creates potential variation. It creates the necessary electric field to separate charges: e- from h+.
CB
VB
VB
CBMaterial A
Material B
interface
-
+
Energy band bending.
Electric field = - grad V
Force = E x charge
energy = V x charge
Note that quasi-Fermi level EFB should go up,
CB & VB go down for B.
EFB
Note that quasi-Fermi level EFA should go down,CB & VB go up for A.
EFA
2
BC
BV
BV
BC
Cathode
Material A A
node
Material
B
interfaceFigure SI-1-2, representing the energy staggered interface. It represents the charge separation mechanism in a picturial slow motion maner. Excitation of such an energetic structure with only 4 photons.
+
-
2hv
2hv
-
+
+
-
+
- - - - -
++++
-
+
hvi
---
+++
-
++ + +
----
+
-+
hvi
+
-
+
-
+
-
+
-
+
-
+
-hvi
Energy balance: 4 hv photons as excitation3 hvi photons emission at interface1 (e-, h+) separated ( 25% efficiency)
hvi is related to the spent energy to separate (e-, h+).Note: photosynthesis is about 5% final efficiency. 3
BC
BV
BV
BC
Cathode
Material A Anode
Material B
interface
hvi
Figure SI-1- 3, representing the energy staggered interface: charge separation mechanism applied to photosynthetic first step processes. Note the hudge electric field crossing the interface for the AlInAs/InP system (see text). For organic molecules, this electric field should be much higher since the excitonic attraction is much higher than for inorganic materials.
-
+
-
+ +
+
-
-
waterO2
CO2
+ H2O sucrose
Interface electric field crossing the interface
Eband-bending ≈105 V/cm
4
Why is the interface emission peak so large? See it in the nexts slides…
5
Figure SI-1-4, representing the interface physical parts linked to the interface emission peak. All the terms of the equation below should change with the excitation intensity. Mainly ∆Qe + ∆Qh should change more than the others terms. This explain why the interface PL & EL emission peaks’ are so large.
Note: no quantum mechanics selection rules, for e- & h+ recombination at the interface 6
interface
hvi
<-- electr
ons
holes -
->
= S + Qe + Qh - Ex
Qe
Qh
S
_ + Ex=interaction
Material A
Material B
h absorption is possible
Energy levels to be filled up with h+, upon
light excitation.
Quasi-triangular shape quantum
well for e-.
Figure SI-1-5, representing the interface physical parts linked to the interface recombination/emission peak. The interface recombination and emission depends on the e- & h+ wavefunctions’ interface overlap. The 1 to 2 nm wavefunction penetration is for the AlInAs/InP system (see text).
No quantum mechanics selection rules for recombination;
because e- & h+ are seated on different materials. 7
interface
hv
<-- electr
ons
holes -
->
emission & absorption
Material A
Material B
Permanent e-population inversion
(µe- > µh+)
+~1 nm
- ~ 2 nm
Is there any meaning to talk about lifetime measurements
for all these hazardous energy levels (e-, h+) recombination?
S
h+ wavefunction
e- wavefunction
