Deoxyribonucleic acid-based electron selective contact for crystalline silicon solar cells

This is the peer reviewed version of the following article: Tom, T. [et al.]. Deoxyribonucleic acid-based electron selective contact for crystalline silicon solar cells. "Advanced materials technologies (Weinheim)" [en línia], 18 Octubre 2022, [Consulta: 12 Desembre 2022]. Disponible a: http://hdl.handle.net/2117/377832, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1002/admt.202200936. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.Development of carrier selective contacts for crystalline silicon solar cells has been recently of great interest toward the further expansion of silicon photovoltaics. The use of new electron and hole selective layers has opened an array of possibilities due to the low-cost processing and non-doping contacts. Here, a non-doped heterojunction silicon solar cell without the use of any intrinsic amorphous silicon is fabricated using Deoxyribonucleic acid (DNA) as the electron transport layer (ETL) and transition metal oxide V2O5 as the hole transport layer (HTL). The deposition and characterization of the DNA films on crystalline silicon have been studied, the films have shown a n-type behavior with a work function of 3.42 eV and a contact resistance of 28 mO cm2. This non-doped architecture has demonstrated a power conversion efficiency of 15.6%, which supposes an increase of more than 9% with respect to the cell not containing the biomolecule, thus paving the way for a future role of nucleic acids as ETLs.T.T. and E.R. shared co-first authorship. This research was supported by Spanish government through grants PID2019-109215RB-C41, PID2019-109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/ AEI/10.13039/501100011033. One of the authors (T.T.) acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456). Besides this, the authors thank technical staff from Barcelona Research Center in Multiscale Science and Engineering from Universitat Politècnica de Catalunya for its expertise and helpful discussions over XPS results, Dr. Oriol Arteaga Barriel from Universitat de Barcelona for the thickness measurements, and also Guillaume Sauthier from Catalan Institute of Nanoscience and Nanotechnology for his contribution through UPS measurements and discussions.Peer ReviewedPostprint (published version

Expanding the perspective of polymeric selective contacts in photovoltaic devices using branched polyethylenimine

This work studies the use of polymeric layers of polyethylenimine (PEI) as an interface modification of electron-selective contacts. A clearly enhanced electrical transport with lower contact resistance and significant surface passivation (about 3 ms) can be achieved with PEI modification. As for other conjugated polyelectrolytes, protonated groups of the polymer with their respective counter anions from the solvent create an intense dipole. In this work, part of the amine groups in PEI are protonated by ethanol that behaves as a weak Brønsted acid during the process. A comprehensive characterization including high-resolution compositional analysis confirms the formation of a dipolar interlayer. The PEI modification is able to eliminate completely Fermi-level pinning at metal/semiconductor junctions and shifts the work function of the metallic electrode by more than 1 eV. Induced charge transport between the metal and the semiconductor allows the formation of an electron accumulation region. Consequently, electron-selective contacts are clearly improved with a significant reduction of the specific contact resistance (less than 100 mO·cm2). Proof-of-concept dopant-free solar cells on silicon were fabricated to demonstrate the beneficial effect of PEI dipolar interlayers. Full dopant-free solar cells with conversion efficiencies of about 14% could be fabricated on flat wafers. The PEI modification also improved the performance of classical high-efficiency heterojunction solar cells.This research has been supported by the Spanish government through Grants PID2019-109215RB-C41, PID2019109215RB-C43, PID2020-115719RB-C21, and PID2020116719RB-C41 and funded by MCIN/AEI/10.13039/ 501100011033. Besides this the authors would like to thank Prof. Jordi LLorca for his expertise and helpful discussions of XPS results, as well as Dr. Rodrigo Fernández-Pacheco of the Laboratorio de Microscopias Avanzadas (LMA-INA) of Zaragoza for the HRTEM images and EDS and EELS analysis, and Guillaume Sauthier from ICN2 for his contribution through UPS measurements and discussions.Peer ReviewedPostprint (published version

Polyethienimine interface dipole tuning for electron selective contacts

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This work studies the use of thin layers of polyethylenimine (PEI) as an interface film to produce electron selective contacts for photovoltaic applications in crystalline silicon. Generally, in conjugated polyelectrolytes such as PEI with a high Lewis basicity, charge is accumulated along the chain of the polymer and counter anions from the solvent create an intense dipole array. In this work, part of the amine groups in PEI are protonated by the solvent that behaves as a weak Bronsted acid during the process. The PEI band modification is able to eliminate Fermi level pinning at metal/semiconductor junctions as it shifts the work function of the metallic electrode by more than 1 eV. As a consequence, induced charge transport between the metal and the semiconductor forms an electron accumulation region and promotes enhanced selectivity.This research has been supported by Spanish government through Grants PID2019-109215RB-C41 (SCALED), PID2019-109215RB-C43, PID2020-116719RB-C41 (MATER ONE) and PID2020-115719RB-C21 (GETPV) and funded by MCIN/AEI/ 10.13039/501100011033. Besides this the work is also supported by the international Grants SENESCYT-2018 funded by Ecuadorian government.Peer ReviewedPostprint (author's final draft