Coupling light into emerging
thin film photovoltaics (PVs)
Ross Hatton*
Department of Chemistry, University of Warwick.
Organic PV
Lead free perovskite PV
(In collaboration with Prof. Richard
Walton - Warwick )
*ross.hatton@warwick.ac.uk
Organic Photovoltaics
Chlorophyll
Cu phthalocyanine
Tang, Appl. Phys. Lett. 48 (1986) 183.
• Earth abundant elements
(cheap, non-toxic)
Cl
Cl
• Strong absorbers
B
N
• Tuneable properties
(optical, electronic, processing)
‘Dial-a -semiconductor’
*Sullivan et al., Advanced Energy Materials (2011) 1, 352–355.
N
N
N
N
Cl
Cl
~ 12%
Cl
N
Cl
Cl
Thin film device architecture
d < 1 micron 100-1000 times thinner
than c-Si
Transparent electrode and
supporting substrate
Light in
Challenges: Reducing reliance on costly materials
SEM
• Brittle
• Complex (chemically)
• Costly (processing and
materials bill)
Sub-10 nm Au films on glass
8 nm Au on glass
15 W sq-1
6 W sq-1
SPR
• > 300 Ω sq-1
• Extremely fragile
• Transparency < 70%
® Poor adhesion to substrate!
Nano-layer molecular adhesive
Improving interfacial adhesion without contributing to light absorption
?
~ 0.8 nm
Thiol : Amine
1 : 3.4
‘thiol’
‘primary amine’
Bond strengths: Au-SH : strong (~40 kcal/mol), Au-NH2 : moderate (via N lone pair, ~8 kcal/mol)
*Patent application filed 2011.
Vapour phase
15 W sq-1
6 W sq-1
H. Stec, R. William, T. Jones, R. A. Hatton, Advanced Functional Materials, 21 (2011) 1709.
Robustness testing
Untreated
Toluene
Water
IPA
Sheet resistance / Ω sq-1 (±1.0)
Molecular adhesive
11.3
11.7
11.3
12.2
None
>300
>400
¥
>300
Metal film characterisation: AFM
~ 0.4 nm
*Patent application filed 2011.
Organic Photovoltaic device performance
Micro-cavity effects?
Towards low cost and flexible
window electrodes.
Translating to flexible polyester substrates
‘technologically important substrates’
O
O3
O
XPS
PEN
N 1s
7.2 ± 0.05
S 2s
2.1 ± 0.05
N:S ratio
3.4 ± 0.1
PET
7.3 ± 0.05
2.1 ± 0.05
3.4 ± 0.1
Coinage metals on polyester substrates
Ag
Cu
Au
H.M. Stec, R. A. Hatton, ACS Applied Materials and Interfaces 4(11) (2012) 6013-6020.
Copper window electrodes which improve with
oxidation*
*Oliver S. Hutter, Helena M. Stec and Ross A. Hatton, Advanced Materials, 25 (2013) 284-288.
Now 7 W sq-1
•
A built-in dessicant
XPS: Cu 2p3/2
No CuO
M. Tyler et al. ChemPhysChem (Special issue on Organic Electronics (2015)).
Auger: LMM
No Cu2O
A Hybrid Copper : Tungsten Sub-oxide Window
Electrode*
• Wrong side for anti-reflecting coating
• Must also conduct charge (limits choice / thickness)
Oliver S. Hutter, Ross A. Hatton Advanced Materials 27(2) (2015) 326-331.
Patent application filed 2014.
Rapid solid state diffusion at room temperature
(XPS, UPS and resistivity)
Organic Photovoltaic device performance
Micro-cavity effects?
Organic Photovoltaic device performance
Yes!
The team
2012
2014
Thank you for listening!