Diffusion-Free Organic Hole Selective Contacts for Silicon Solar Cells

Li, Li-Yu; Chen, Chun-Heng; Chiu, Chi-Lin; Li, You-Lan; Meng, Hsin‐Fei; Yu, Peichen

doi:10.1109/pvsc40753.2019.8981369

Cited by 1 publication

(1 citation statement)

References 9 publications

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“…Carrier selective contacts based on organic molecules have attracted research interest due to their highly adjustable electronic and chemical properties and cheaper fabrication process. , Interfacial layers based on organic molecules have been shown to modify the apparent work function (WF) of metallic electrodes. In this sense, the electric dipole moment of these interlayers has been proven to be capable of shifting the electronic band alignment across the interface and therefore the properties of the metal/semiconductor junction. , Various organic molecules investigated for ETL layers such as conjugated polyelectrolyte (CP) poly [(9,9-bis(3′-( N , N -dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene), amino acids such as glycine, histidine, phenylalanine and HTLs such as poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate), fluorescent polymers poly(9,9-dioctylfluorenyl-2,7-diyl), and Lissamine Green B have reported good efficiencies beyond 14%. − …”

Section: Introductionmentioning

confidence: 99%

Expanding the Perspective of Polymeric Selective Contacts in Photovoltaic Devices Using Branched Polyethylenimine

Ros

Tom

Rovira

et al. 2022

ACS Appl. Energy Mater.

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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 mΩ·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.

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