Bulk Defect Suppression of Micrometer-Thick Perovskite Single Crystals Enables Stable Photovoltaics

Abstract

Metal halide perovskite single crystals have become emerging candidates for photovoltaic applications due to their better optoelectronic properties and higher stability than their polycrystalline thin-film counterparts. However, in contrast to the rapid enhancement of power conversion efficiency (PCE), the operational stability of single-crystal perovskite solar cells (PSCs) remains far lagging behind. Herein, it is discovered that widely investigated 20 μm-thick single-crystal PSCs show poor operational stability, which is assigned to low crystal quality of these thin single crystals. Subsequently, the crystal quality of formamidinium0.55methylammonium0.45 lead triiodide (FA0.55MA0.45PbI3) thin single crystals are optimized by adjusting the ion diffusion velocity in confined space, leading to lower trap density, larger ion migration activation energy, and reduced light-induced degradation of material properties. As a result, stable single-crystal PSCs with no efficiency degradation after 330 h of continuous operation at the maximum power point under 1 sun illumination are achieved. Moreover, thickness-dependent device efficiency discloses an ultralong carrier transport length of 200 μm in FA0.55MA0.45PbI3 thin single crystals, which is instructive for developing lateral-structure solar cells.

Recent progress of crystal orientation engineering in halide perovskite photovoltaics

“…This value approaches the mobilities obtained in these MAPbI 3 single crystals. 85,86 It was reported in another study that orientationally pure crystalline (OPC) perovskite films with a strong orientational preference to the (112) and ( 200) planes can be fabricated through a temperature-gradient-assisted solidification process; the field-effect transistor (FET) devices based on these OPC films show giant anisotropy in field-effect charge mobility when characterized in different directions. 87 These results confirm the orientation-dependent charge transport properties of tetragonal MAPbI 3 thin films.…”

Near-infrared polarization-sensitive photodetectionviainterfacial symmetry engineering of an Si/MAPbI3heterostructural single crystal

“…Methylammonium lead iodide (MAPbI 3 ) single crystals (SCs) have been reported as a star semiconductor material in the perovskite family owing to their large optical absorption coefficient, excellent optoelectronic properties and accessible solution preparation, which attracts significant focus devoted to MAPbI 3 -based photodetectors and other optoelectronic devices. 17–23 For example, Huang and co-works reported that the diffusion length of MAPbI 3 SC is up to 175 μm under 1 sun illumination, leading to a high responsivity of 35 mA W −1 . Moreover, this device exhibited a peak value of external quantum efficiency at the NIR region (810 nm).…”

Double Layer Composite Electrode Strategy for Efficient Perovskite Solar Cells with Excellent Reverse-Bias Stability

“…Irreversible chemical reactions between the metal electrode and perovskite layer can appear and can deteriorate perovskite film and adjacent layers. For instance, metal ions from the electrode can diffuse to the perovskite layer under reverse bias, resulting in deep-level defects in the perovskite layer and undesirable S-shape curves in performance test [12][13][14][15]. For the PSCs under light irradiation and the electric field, iodine ions can diffuse toward the metal electrode, leaving iodine vacancy defects in the perovskite [16,17].…”