Deterministic fabrication of 3D/2D perovskite bilayer stacks for durable and efficient solar cells

Abstract

Realizing solution-processed heterostructures is a long-enduring challenge in halide perovskites because of solvent incompatibilities that disrupt the underlying layer. By leveraging the solvent dielectric constant and Gutmann donor number, we could grow phase-pure two-dimensional (2D) halide perovskite stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. Characterization reveals a 3D–2D transition region of 20 nanometers mainly determined by the roughness of the bottom 3D layer. Thickness dependence of the 2D perovskite layer reveals the anticipated trends for n-i-p and p-i-n architectures, which is consistent with band alignment and carrier transport limits for 2D perovskites. We measured a photovoltaic efficiency of 24.5%, with exceptional stability of T 99 (time required to preserve 99% of initial photovoltaic efficiency) of >2000 hours, implying that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency.

How Stable Is the 2D/3D Interface of Metal Halide Perovskite under Light and Heat?

“…Despite the impressive breakthroughs in attaining photoconversion efficiencies, the long-term operational stability of perovskite solar cells remains a challenge. , Surface treatments to passivate defects or use triple cations for metal halide perovskites have proven to be effective in improving the performance and stability. − More recently, the focus has shifted to the introduction of a 2D layer over the bulk 3D perovskite film. − Creation of a 2D/3D interface is thought to significantly improve the stability of perovskite solar cells. − …”

Go beyond the limit: Rationally designed mixed-dimensional perovskite/semiconductor heterostructures and their applications

“… 146 The perovskite/semiconductor heterojunctions can facilitate the rapid transfer of the photo-generated charge carriers, thus avoiding the perovskite decomposition induced by carrier accumulation. SWCNTs, 117 , 147 small molecules, 97 , 114 , 148 and 2D materials 149 , 150 , 151 are all promising candidates for improving perovskite stability and charge transporting property. Steric hindrance effect.…”

Illustrating the Key Role of Hydrogen Bonds in Fabricating Pure-Phase Two-Dimensional Perovskites

“…Two-dimensional (2D) perovskites are emerging as next-generation functional materials for environmentally stable optoelectronic devices due to their high color purities, superior emission efficiencies, and low-cost solution processabilities. − They are composed of n -layer perovskite flakes separated by bilayers of large organic cations, forming a mixture of quantum well (QW) domains. − The critical control over the domain distribution of 2D perovskite thin films is crucial for their applications in photovoltaics or light-emitting diodes. For example, a 2D perovskite layer with inhomogeneous domain distribution can widen the distribution of electronic states at the band edges, leading to open-circuit voltage loss and carrier transport blockage − of solar cells.…”