Nanoporous anodic alumina with ohmic contact between substrate and infill: Application to perovskite solar cells

Abstract

The use of a nanostructured aluminum substrate as the cathode for a perovskite photovoltaic device is described. This cathode consists of an aluminum substrate onto which a highly ordered array of aluminum oxide tubular pores was grown via anodization. The 1‐μm thick pores – arranged in a closed‐packed hexagonal pattern – were subsequently selectively etched at the bottom to remove the so‐called aluminum oxide barrier layer. The subsequent infiltration of the pores with the components of a methylammonium lead iodide perovskite solar cells, and the completion with a semi‐transparent anode, have shown to allow the establishment of an ohmic contact between the substrate itself and the components infiltrated into the Al2O3 pores. Indeed, a clear rectifying behavior was observed on the full devices, as well as modest photovoltaic conversion efficiencies. This paper demonstrates that an ohmic contact can be established between the aluminum substrate from which nanoporous anodic alumina was grown, and that the pores can be used to compartmentalize the infill material down to the nanoscopic level.

Nanoporous Anodic Alumina Photonic Crystals for Sunlight Harvesting Applications: A Perspective

“…Using a similar concept, Montero‐Rama et al prepared a perovskite solar cell in which NAA–FPIs were used to contain the components of the device (i.e., titanium dioxide—TiO 2 , methylammonium lead iodide—MAPbI 3 , and spiro‐OMeTAD) and the aluminum substrate on its backside functions as the cathode. [ 184 ] Despite achieving a low PCE of 0.06%, this study demonstrated that NAA–FPIs can be filled with multiple materials to engineer their structure at the nanoscale and use the aluminum substrate on its backside as an ohmic contact. On the other hand, El‐Said et al used the aluminum substrate of NAA–FPIs containing Cu impurities as the photoanode in dye‐sensitized solar cells (DSSCs).…”

“…In the context of this perspective, the integration of NAA–PCs into solar cell systems has been explored to break through some of these technological bottlenecks, harnessing the unique geometric, optical, thermal, and electrically insulative properties of NAA to maximize photon‐to‐electron conversion rates in solar cell systems. In particular, NAA‐based Fabry–Pérot interferometers (NAA–FPIs) have been integrated into PV cells as scaffolds for PV materials, [ 184,185 ] radiative coolers, [ 186 ] electrodes, [ 184,187 ] and antireflective coatings. [ 163,164,188 ] NAA–FPIs are composed of straight cylindrical nanopores featuring a homogeneous distribution of effective refractive index in depth [23a] .…”

“…[23a] In PV cells, the characteristic barrier oxide layer at the bottom side of NAA-FPIs is often selectively etched to provide a physical connection between the n-and p-type sections of the PV cell (Figure 9). [163,164,[184][185][186]188] Kwon et al developed a semitransparent, highly efficient, 1D nanostructured perovskite solar cells integrating an NAA-FPI as an insulating scaffold layer (Figure 9a). [185] NAA-FPIs are used as a template to geometrically conform the PV cell precursors to generate vertically aligned perovskite pillars, eliminating the possibility of shunting current.…”