Towards a Sustainable Energy Future: Fully Printable Carbon-Based Perovskite Solar Cells with Overcome Charge Transport Limitation and Improved Light-Harvesting Efficiency
Simone Mastroianni a b, Lukas Wagner a, Gayathri Mathiazhagan a c, Dmitry Bogachuk a, Kübra Yasaroglu Ünal a d, Shankar Bogati a, Thomas Kroyer a, Michael Daub e, Harald Hillebrecht e, Jean-Luc Rehspringer d, Aziz Dinia d, Andreas Hinsch a
a Fraunhofer Institute for Solar Energy Systems ISE, Germany, Heidenhofstraße, 2, Freiburg im Breisgau, Germany
b Freiburg Materials Research Center FMF, Albert-Ludwigs-University Freiburg, DE, Stefan-Meier-Straße, 25, Freiburg im Breisgau, Germany
c Albert-Ludwigs-University Freiburg, Department of Microsystems Engineering (IMTEK), Georges-Köhler-Allee, 103, Freiburg im Breisgau, Germany
d IPCMS, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, B. P. 43, 67034 Strasbourg Cedex 2, France
e Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Analytische Chemie, Albertstraße, 21, Freiburg im Breisgau, Germany
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP20)
Tsukuba-shi, Japan, 2020 January 20th - 22nd
Organizers: Michio Kondo and Takurou Murakami
Invited Speaker Session, Simone Mastroianni, presentation 106
Publication date: 14th October 2019

A projection of worldwide CO2 emissions of the future PV industry is initially presented. We investigate the development of gross global CO2-emissions from the PV industry towards a sustainable energy future. This is the basis for our motivation to propose a fully printed integrated carbon-based PV module concept as alternative pathway to strongly reduce the carbon footprint to the ultimate lower limit of the glass substrate fabrication. For this glass-glass sealed perovskite solar cell (PSC) concept in which the perovskite is introduced “in-situ” as a last fabrication step, we show a certified-stabilized efficiency of 9.3 %. We calculated for the in-situ PSC an emission of 3.67 g CO­2-eq/kWh, which is just 4.8 % of the value for mono-Si PV modules.

With the goal to increase the efficiency towards an ambitious - yet achievable - 20%, we propose three approaches aimed at increasing the light-harvesting efficiency and at obtaining a uni-directional charge transport. These approaches have been experimented on monolithic carbon-based PSCs (C-PSCs):

1. A perovskite molten-salt approach obtained through liquefaction and recrystallization of CH3NH3PbI3 perovskite with methylamine - MA0(CH3NH2) gas. The fabricated C-PSC showed optimized perovskite self-assembling and improved crystallization with efficient charge transport and extraction, resulting in a high VOC of 1 V, which is the highest VOC reported for a monolithic HTL-free MAPbI3 device. This device has been certified under steady-state with a value of 12.6%. Furthermore, we unravel how methylamine interacts with perovskite during its liquid-to-solid transition by using a combination of Raman spectroscopy, single-crystal XRD and a real-time photoluminescence (PL) monitoring during the crystallization.

2. Monolithic C-PSCs commonly use thick >1 µm printed electrically insulating space layer to prevent charge recombination at the mp‑TiO2/carbon interface. We show a reproducible large-area procedure to replace this thick space layer with an ultra-thin dense 40 nm sputtered Al2O3, which is able to prevent ohmic shunts and to efficiently reduce the charge recombination at the mp-TiO2/carbon interface. Herewith, transport limitations related so far to the hole diffusion path length inside the thick mesoporous space layer have been omitted by concept. A stable VOC of 1 V using MAPbI3 perovskite has been achieved with stabilized device performance of 12.1%.

3. The third approach show how embedding cross-linked poly(methyl-methacrylate) (PMMA) nanoparticles of tunable size into the mesoporous TiO2 scaffold via sol-gel process can directly influence the pore size of the final film and, therefore, enhance the light-harvesting efficiency. SEM and 3D nano-tomography (from FIB-SEM) demonstrate the pore size engineering of the mp-TiO2 layer. The impregnated C-PSC filled with double-cation mixed halide FA0.83Cs0.17PbI2.64Br0.36 perovskite photoabsorber, reaches VOC close to 1 V with a power conversion efficiency (PCE) of 12.7%.

This work has been partially funded by the Project PROPER supported by “EIG Concert Japan” and financed from the German Federal Ministry of Education and Research under the funding number 01DR19007.

In addition, it has been funded by the project UNIQUE, supported under the umbrella
of SOLAR-ERA.NET_Cofund by ANR, PtJ, MIUR, MINECO-AEI, SWEA. SOLAR-ERA.NET is supported by the European Commission within the EU Framework Programme for Research and Innovation HORIZON 2020 (Cofund ERA-NET Action, N° 691664).

This research has further received funding from the European Union’s
Horizon 2020 research and innovation programme under grant agreement No
763989 APOLO.

D.B. and L.W. acknowledge the scholarship support of the German Federal Environmental Foundation (DBU). G.M. acknowledges the scholarship support of State Graduate Funding Program of Baden-Württemberg (LGFG).

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