To realize chromic photovoltaic and conventional photovoltaic architectures, carbon-nanotube films have been identified as a promising replacement for Spiro-OMeTAD as hole-selective transport layers in perovskite photovoltaic devices. While Spiro works well as a hole-selective transport layer, there is serious concern that it is also a significant source of perovskite-cell-performance degradation over time due to migration of Li atoms into the perovskite bulk.
Researchers at the National Renewable Energy Laboratory (NREL) have created a novel bilayer of carbon nanotubes, which is used as a hole transport layer. Specifically, a first carbon-nanotube layer (wrapped in a P3HT polymer) provides an energetically favorable interface with the perovskite absorber layer, while the second carbon-nanotube layer doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is optimized for hole transport out of the perovskite device. This bilayer improves the stability of the absorber layer and enables perovskite device architectures desiring a transparent hole-selective contact (e.g. for building-integrated photovoltaic window applications).
For further information about this technology or advances in NREL's broader perovskite portfolio, please visit NREL's Chromic Technologies for Photovoltaic Applications Portfolio Summary or Perovskite Patent Portfolio Website or contact Bill Hadley at firstname.lastname@example.org.
Applications and Industries
- Thermochromic or electrochromic photovoltaic windows
- Building integrated photovoltaics (BIPV)
- Improved absorber stability
- Can be used in transparent perovskite device architectures