# Nanoparticle-Mediated Interface Engineering for Uniform, Reproducible Electron Transport Layers in Scalable Perovskite Solar Cells

## TL;DR

This paper introduces a method using nanoparticles to improve the performance and reliability of large-scale perovskite solar cells.

## Contribution

The use of Al2O3 and SnO2 nanoparticles to engineer electron transport layers in scalable perovskite solar cells is novel.

## Key findings

- Nanoparticle interlayers improve ETL uniformity and reduce device failure rates by 50%.
- SnO2 interlayers achieve a champion PCE of 11.0% in small-area devices and show robustness in larger modules.
- Al2O3 suppresses recombination but slightly reduces short-circuit current.

## Abstract

As lab-scale perovskite
solar cells (PSCs) approach their efficiency
limits, reproducing this performance in large-area, manufacturable
devices remains challenging. Here, we show that printing interlayers
of metal oxide nanoparticles, specifically Al2O3 and SnO2, can systematically control the morphology and
interfacial energetics of solution-processed PC61BM electron
transport layers (ETLs) in flexible roll-to-roll printed PSCs. These
nanoparticle interlayers enhance ETL uniformity, reduce pinholes,
and increase shunt resistance, improving power conversion efficiencies
(PCEs) and reducing device failure rates by 50%. Through a combination
of systematic device characterization, morphological, spectroscopic
and energetic analysis, coupled with drift-diffusion simulations,
the distinct roles of insulating (Al2O3) and
semiconducting (SnO2) nanoparticle interlayers in mediating
carrier extraction and recombination are elucidated. Al2O3 suppresses interfacial recombination and improves device
reproducibility, albeit with some penalty in short-circuit current,
whereas SnO2 enhances electronic coupling and charge extraction,
delivering a champion PCE of 11.0% (active area: 0.5 cm2). Incorporating SnO2 interlayers into larger-area modules
(active area: 7.2 cm2) further demonstrates the robustness
of this strategy under manufacturing-relevant conditions. Together,
these results provide an important framework for nanoparticle-mediated
interface engineering and establish a simple, effective, and scalable
route to improving both performance and yield in printed large-area
PSCs.