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World Journal of Nano Science and Engineering http://www.scirp.org/journal/wjnse Paper ID: 4400054 Support Information: SI-1 Energy staggered interface: electrical charge separation mechanism. Title Interface recombination & emission applied to explain photosynthetic mechanisms for

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Title interface recombination emission applied to explain photosynthetic mechanisms for

World Journal of Nano Science and Engineering

http://www.scirp.org/journal/wjnse

Paper ID: 4400054

Support Information: SI-1

Energy staggered interface: electrical charge separation mechanism.

Title

Interface 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

1


Title interface recombination emission applied to explain photosynthetic mechanisms for

Energy band bending.

Electric field = - grad V

Force = E x charge

energy = V x charge

interface

-

CB

CB

EFB

Material A

Material B

EFA

VB

VB

Note that quasi-Fermi level

EFA should go down,

CB & VB go up for A.

+

Note that quasi-Fermi level

EFB should go up,

CB & VB go down for B.

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+.

2


Title interface recombination emission applied to explain photosynthetic mechanisms for

Figure 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.

interface

Cathode

-

-

-

-

-

-

-

-

-

BC

-

-

-

-

-

-

-

-

-

-

-

-

-

BC

-

Material

A

Anode

-

hvi

hvi

hvi

Material B

+

BV

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

BV

+

+

+

+

+

+

+

+

Energy balance: 4 hv photons as excitation

3 hvi photons emission at interface

1 (e-, h+) separated ( 25% efficiency)

hvi is related to the spent energy to separate (e-, h+).

Note: photosynthesis is about 5% final efficiency.

2hv

2hv

3


Title interface recombination emission applied to explain photosynthetic mechanisms for

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.

-

-

+

-

+

+

CO2

+ H2O

sucrose

Eband-bending≈105 V/cm

water

O2

Interface electric field

crossing the interface

interface

Cathode

BC

Anode

BC

-

hvi

Material A

Material B

BV

+

BV

4



Title interface recombination emission applied to explain photosynthetic mechanisms for

interface nexts slides…

Material B

Material A

Quasi-triangular

shape quantum

well for e-.

<-- electrons

Qe

S

hvi

= S + Qe + Qh - Ex

_

+

h absorption is possible

Energy levels to be

filled up with h+, upon

light excitation.

Ex=

interaction

Qh

holes -->

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.

6

Note: no quantum mechanics selection rules, for e- & h+ recombination at the interface


Title interface recombination emission applied to explain photosynthetic mechanisms for

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).

Material B

Material A

Permanent e-

population inversion

(µe- > µh+)

<-- electrons

+

~ 2 nm

-

S

emission & absorption

hv

Is there any meaning

to talk about lifetime measurements

for all these hazardous energy

levels (e-, h+) recombination?

~1 nm

holes -->

interface

e- wavefunction

h+ wavefunction

No quantum mechanics selection rules for recombination;

because e- & h+ are seated on different materials.

7