Facet Engineering for Stable, Efficient Perovskite Solar Cells

Abstract

Facet engineering is an important strategy for tuning the physical, chemical, and electronic properties of a crystal surface, and it also provides an effective route to improve the device performance in many fields. Complex crystal structures with rough morphologies have been observed for most of the hybrid perovskite thin films. Thus, it is speculated whether high-quality crystals with tunable facets can be formed on a perovskite thin film and how the facet properties can influence the device performance. More importantly, the high-quality crystals and tunable facets are also effective strategies to further improve the efficiency and stability of perovskite devices. This perspective provides the challenges to achieving high-quality crystals with tunable facets and discusses the crystal shape, facet properties, and several prospects of facet engineering on perovskite thin films.

Recent progress of crystal orientation engineering in halide perovskite photovoltaics

“…As a result, the energy bands of adjacent facets would bend and form an internal electric field, which would influence the photogenerated exciton separation and redistribute the charge carriers between these facets. 74,77 Besides, perovskite surface orientation also affects both hole and electron interfacial transfer toward hole and electron charge transfer layers. 67,78 By combining ab initio calculations and photoelectron spectroscopy studies, Yin et al investigated the electronic structure and charge redistribution at the interface between different surfaces of MAPbI 3 and organic charge transporting layers Spiro-OMeTAD and PCBM.…”

“…113 Considering that the termination of facets is the first place exposed to the external environment, the various atomic arrangement and coordination in the terminations would also affect the stability of the perovskite. 77 For example, the MAPbI 3 material shows facet-dependent beam-sensitivity under electron beam illumination, a (100) exposed MAPbI 3 surface is more stable than the (001) surface. 42 Therefore, more efforts should be devoted to revealing the degradation mechanisms of the oriented perovskites with certain exposed facets to further improve their intrinsic stability.…”

Unveiling facet-dependent degradation and facet engineering for stable perovskite solar cells

“…), and these facets are likely to degrade first ( 16 , 17 ). Thus, understanding the overall stability of the perovskite thin film begins with understanding the stability and degradation behavior of the perovskite facets ( 18 ). Different crystal facets have different atomic arrangements and coordination, which lead to different atomic potential landscapes and, subsequently, to different electronic, physical, and/or chemical properties ( 19 – 21 ).…”

Facet Engineering: A Promising Pathway toward Highly Efficient and Stable Perovskite Photovoltaics

“…Both technical routes are ameliorated through precursor engineering, annealing engineering, and additive engineering, resulting in high-quality as-prepared perovskite films . In conventional silicon-based photovoltaics, solar cells prepared from high-quality monocrystalline films exhibit better photovoltaic properties than their polycrystalline counterparts . Interestingly, perovskite films prepared by spin-coating also show a trend toward monocrystallization in the evolution process …”