skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Attention:

The NSF Public Access Repository (PAR) system and access will be unavailable from 10:00 PM ET on Friday, February 6 until 10:00 AM ET on Saturday, February 7 due to maintenance. We apologize for the inconvenience.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: The role of fullerene derivatives in perovskite solar cells: electron transporting or electron extraction layers?
The synthesis, characterization and incorporation of fullerene derivatives bearing primary, secondary and tertiary nitrogen atoms, which possess different basicities, in perovskite solar cells (PSCs), is reported. In this work, we tested the compounds as conventional electron transporting materials (ETMs) in a single layer with phenyl-C 61 -butyric acid methyl ester (PC 61 BM) as control. Additionally, we tested the idea of separating the ETM into two different layers: a thin electron extracting layer (EEL) at the interface with the perovskite, and an electron transporting layer (ETL) to transport the electrons to the Ag electrode. The compounds in this work were also tested as EELs with C 60 as ETL on top. Our results show that the new fullerenes perform better as EELs than as ETMs. A maximum power conversion efficiency (PCE) value of 18.88% was obtained for a device where a thin layer (∼3 nm) of BPy-C 60 was used as EEL, a higher value than that of the control device (16.70%) with only pure C 60 . Increasing the layer thicknesses led to dramatically decreased PCE values, clearly proving that the compound is an excellent electron extractor from the perovskite layer but a poor transporter as a bulk material. The improved passivation ability and electron extraction capabilities of the BPy-C 60 derivative were demonstrated by steady state and time-resolved photoluminescence (SS-and TRPL) as well as electrochemical impedance spectroscopy (EIS) and X-Ray photoelectron spectroscopy (XPS) measurements; likely attributed to the enhanced basicity of the pyridine groups that contributes to a stronger interaction with the interfacial Pb 2+ .  more » « less
Award ID(s):
1801317
PAR ID:
10276914
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Journal of Materials Chemistry C
ISSN:
2050-7526
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; ; ; ; ; et al (, Science)
    Although C60is usually the electron transport layer (ETL) in inverted perovskite solar cells, its molecular nature of C60leads to weak interfaces that lead to non-ideal interfacial electronic and mechanical degradation. Here, we synthesized an ionic salt from C60, 4-(1',5′-dihydro-1'-methyl-2'H-[5,6] fullereno-C60-Ih-[1,9-c]pyrrol-2'-yl) phenylmethanaminium chloride (CPMAC), and used it as the electron shuttle in inverted PSCs. The CH2-NH3+head group in the CPMA cation improved the ETL interface and the ionic nature enhanced the packing, leading to ~3-fold increase in the interfacial toughness compared to C60. Using CPMAC, we obtained ~26% power conversion efficiencies (PCEs) with ~2% degradation after 2,100 hours of 1-sun operation at 65°C. For minimodules (four subcells, 6 centimeters square), we achieved the PCE of ~23% with <9% degradation after 2,200 hours of operation at 55°C. 
    more » « less
  2. ; ; ; ; ; ; ; ; (, IEEE)
    Colloidal quantum dots (CQDs) are promising materials for photovoltaic applications due to their solution processibility and size-dependent band gap tunability. The electron transport layer (ETL) is an important component of PbS CQD solar cells, and the quality of the zinc oxide nanoparticle (ZnO NP) ETL film significantly impacts both the power conversion efficiency (PCE) and fabrication yield of CQD solar cells. We report on multiple methods to improve the quality of ZnO NP ETL films and demonstrate increased PCE and device yield in standard CQD solar cells employing optimized ZnO NP films. We also discuss the application of these methods in an inverted CQD solar cell architecture. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, RSC Advances)
    The synthesis and characterization of a family of [60]fullerocurcuminoids obtained via Bingel reactions is reported. The new C 60 derivatives include curcumin and curcuminoids with a variety of end groups. Preliminary biological experiments show the potential activity of the compound containing a curcumin addend, which exhibits moderate anti-HIV-1 and radical scavenger properties, but no anti-cancer activity. In addition, the new fullerocurcuminoids exhibit HOMO/LUMO energy levels that are reasonably matched with those of perovskites and when they were tested in perovskite solar cells (PSCs) as the electron transporting material (ETM), photoconversion efficiencies ranging from 14.04–14.95% were obtained, whereas a value of 16.23% was obtained for [6,6]-phenyl-C 61 -butyric acid methyl ester ( PC61BM ) based devices. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; (, Journal of Materials Chemistry C)
    In this work, two new C 70 isomers, α and β bis(2-(thiophen-2-yl)ethyl)-C 70 -fullerene mono-adducts (DTC 70 ), were synthesized, characterized and used as electron transporting materials (ETMs) in perovskite solar cells (PSCs). Our results show that the α isomer improves both the J sc and FF values of the devices, when compared to the results for the β-isomer and to those for phenyl-C 70 -butyric acid methyl ester ( PC71BM ), used as control. Devices based on α-DTC70 achieved a power conversion efficiency (PCE) of 15.9%, which is higher than that observed with PC71BM (15.1%). 
    more » « less
  5. ; ; ; ; ; ; ; (, Advanced Materials)
    The combined effects of compact TiO2 (c-TiO2) electron-transport layer (ETL) are investigated without and with mesoscopic TiO2 (m-TiO2) on top, and without and with an iodine-terminated silane self-assembled monolayer (SAM), on the mechanical behavior, opto–electronic properties, photovoltaic (PV) performance, and operational-stability of solar cells based on metal-halide perovskites (MHPs). The interfacial toughness increases almost threefold in going from c-TiO2 without SAM to m-TiO2 with SAM. This is attributed to the synergistic effect of the m-TiO2/MHP nanocomposite at the interface and the enhanced adhesion afforded by the iodine-terminated silane SAM. The combination of m-TiO2 and SAM also offers a significant beneficial effect on the photocarriers extraction at the ETL/MHP interface, resulting in perovskite solar cells (PSCs) with power-conversion efficiency (PCE) of over 24% and 20% for 0.1 and 1 cm2 active areas, respectively. These PSCs also have exceptionally long operational-stability lives: extrapolated T80 (duration at 80% initial PCE retained) is ≈18 000 and 10 000 h for 0.1 and 1 cm2 active areas, respectively. Postmortem characterization and analyses of the operational-stability-tested PSCs are performed to elucidate the possible mechanisms responsible for the long operational-stability. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email