Supporting Information
Photonic flash sintering of inkjet printed back electrodes for organic photovoltaic applications
Giuseppina Polino a,b, Santhosh Shanmugam c, Guy J.P. Bex a, Robert Abbel a, Francesca Brunetti b, Aldo Di Carlo b, Ronn Andriessen c, Yulia Galagan c,*
Figure S1. Average trend of power conversion efficiencies with time during thermal sintering of the printed full area silver back electrodes (active area 0.089 cm2)
Figure S2. AFM images of surfaces treated with various PFS settings
Figure S3. Scanning electron Microscopy (SEM) images of inkjet printed silver electrodes after (a) thermal sintering at 130 °C for 10 min, (b) Set 4 (II), (c) Set 6 (HI) with PI filter, (d) Set 7 (HI-LE) with PI filter
Figure S4. EQE for all devices analyzed
Table S1. Materials properties used as input for the temperature simulations.
Material / Thickness(nm) / Heat Capacity
(J/kgK) / Thermal Conductivity
(W/mK) / Mass Density
(kg/m3) / Reference**
Dried Silver Ink / 400 / 280 / 43 / 6300 / [1], [2]
PEDOT:PSS / 160 / 1200 / 0.3 / 1250 / [3]
P3HT:PCBM / 230 / 1100 / 0.15 / 1300 / [4], [5], [6]
Combined Organic Layers* / 390 / 1150 / 0.22 / 1300
Zinc Oxide / 50 / 600 / 1.0 / 4500 / [7], [8], [9]
ITO / 130 / 340 / 10.2 / 7100 / [10], [11]
Borosilicate Glass / 700000 / 768 / 1.09 / 2380 / [12]
* The values for the PEDOT:PSS and P3HT:PCBM layers have been averaged for intensive and summed up for extensive properties to form one single organic layer because the simulation program could only handle up to five different materials. Given the small differences in the specific values, this is not expected to have significant influences on the final calculated temperatures.
** References
[1] The heat capacity is the average of the bulk values for the components in the dried ink, weighted by their mass percentage (96 wt% Ag, 4 wt% PVP; determined by TGA). The thermal conductivity is an estimate (10 % of bulk value) not supported by scientific literature (no publications available), but test calculations with values varying from 0.1 to 100 % of bulk Ag revealed only a very minor influence of the exact value (within a few oC).
[2] Moon, K.-S.; Dong, H.; Maric, R.; et al. Thermal behavior of silver nanoparticles for low-temperature interconnect applications. J. Electron. Mater. 2005, 34(2), 168-175. (The mass density is based on the compaction of reported degree (55 - 60 %)).
[3] Lee, S.H.; Park, H.; Kim, S.; Son, W.; Cheong, I.W.; Kim, J.H. Transparent and flexible organic semiconductor nanofilms with enhanced thermoelectric efficiency. J. Mater. Chem. A 2014, 2(20), 7288-7294.
[4] Duda, J.C.; Hopkins, P.E,; Shen, Y.; Gupta, M.C. Thermal transport in organic semiconducting polymers. Appl. Phys. Lett. 2013, 102(25), 251912.
[5] Olson, J.R.; Topp, K.A.; Pohl, R.O. Specific Heat and Thermal Conductivity of Solid Fullerenes. Science 1993, 259(5098), 1145-1148.
[6] Malen, J.A,; Baheti, K.; Tong, T.; Zhao, Y.; Hudgings, J.A.; Majumdar, A. Optical Measurement of Thermal Conductivity Using Fiber Aligned Frequency Domain Thermoreflectance. J. Heat Transfer 2011, 133(8), 081601-081601.
[7] Huang, Z.X.; Tang, Z.A,; Yu, J.; Bai, S. Thermal conductivity of nanoscale polycrystalline ZnO thin films. Physica B 2011, 406(4), 818-823. (Thermal conductivity extrapolated to 50 nm film thickness).
[8] Yi, Q.S.; Wu, X.M.; Tan, Z.C. Preparation and Low Temperature Heat Capacity of the ZnO Nanopowders. J. Inorg. Mater. 2001, 16(4), 620.
[9] El-Brolossy, T.A.; Saber, O.; Ibrahim, S.S. Determining the thermophysical properties of Al-doped ZnO nanoparticles by the photoacoustic technique. Chin. Phys. B 2013, 22(7), 074401. (Mass density determined using compaction of reported degree)
[10] Thuau, D.; Koymen, I.; Cheung, R. A microstructure for thermal conductivity measurement of conductive thin films. Microelectron. Eng. 2011, 88(8), 2408-2412.
[11] Karnakis, D.; Kearsley, A.; Knowles, M. Ultrafast Laser Patterning of OLEDs on Flexible Substrate for Solidstate Lighting. J. Laser Micro/Nanoeng. 2009, 4(3), 218-223.
[12] Values specified by supplier.
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