Highly Efficient and Stable 2D Dion Jacobson/3D Perovskite Heterojunction Solar Cells

High-performance ultraviolet detector based on self-assembled 3D/2D perovskite heterostructure

Heterogeneous assembly of metal halide perovskites (MHPs) structures offers convenience for promoting the interfacial properties of perovskite heterojunctions, which have been widely used in the new generation of photoelectric devices. In this study, three-dimensional (3D) CsPbBr3 quantum dots (CPB QDs) were epitaxially grown on two-dimensional (2D) (BA)2PbBr4 nanoplates (BPB NPs) via self-assembly in a toluene mixing solution. The morphological, structural, and optical properties of the synthesized structure reveal that a highly-qualified interface and coherence were formed between the two different perovskites. These heterostructures (HSs) facilitate the separation and transportation of electrons and holes in opposite directions. Based on this property, a high-performance ultraviolet light detector was fabricated by depositing a layer of CPB@BPB film on a textured silicon (T-Si) substrate. The prepared CPB@BPB/T-Si detector has shown enhanced properties i.e. quick response time, high responsivity (6.9 A W-1), high detection rate (3.17 × 109 jones), and low detection limit (0.24 μW cm-2). This enhanced performance could be attributed to the large light-absorbing area, effective carrier transport channels in BPB NPs, and improved interfacial properties of the CPB@BPB HS.

Rapid Spin Depolarization in the Layered 2D Ruddlesden-Popper Perovskite (BA)(MA)PbI

We report temperature-dependent spectroscopy on the layered (n = 4) two-dimensional (2D) Ruddlesden-Popper perovskite (BA)(MA)PbI. Helicity-resolved steady-state photoluminescence (PL) reveals no optical degree of polarization. Time-resolved PL shows a photocarrier lifetime on the order of nanoseconds. From simultaneously recorded time-resolved differential reflectivity (TRΔR) and time-resolved Kerr ellipticity (TRKE), a photocarrier lifetime of a few nanoseconds and a spin relaxation time on the order of picoseconds was found. This stark contrast in lifetimes clearly explains the lack of spin polarization in steady-state PL. While we observe clear temperature-dependent effects on the PL dynamics that can be related to structural dynamics, spin relaxation is nearly T-independent. Our results highlight that spin relaxation in 2D (BA)(MA)PbI occurs at time scales faster than the exciton recombination time, which poses a bottleneck for applications aiming to utilize this degree of freedom.

Recent Progress on Perovskite-Based Electrocatalysts for Efficient CO2 Reduction

An efficient carbon dioxide reduction reaction (CO2RR), which reduces CO2 to low-carbon fuels and high-value chemicals, is a promising approach for realizing the goal of carbon neutrality, for which effective but low-cost catalysts are critically important. Recently, many inorganic perovskite-based materials with tunable chemical compositions have been applied in the electrochemical CO2RR, which exhibited advanced catalytic performance. Therefore, a timely review of this progress, which has not been reported to date, is imperative. Herein, the physicochemical characteristics, fabrication methods and applications of inorganic perovskites and their derivatives in electrochemical CO2RR are systematically reviewed, with emphasis on the structural evolution and product selectivity of these electrocatalysts. What is more, the current challenges and future directions of perovskite-based materials regarding efficient CO2RR are proposed, to shed light on the further development of this prospective research area.

Improved Efficiency and Stability in 1,5-Diaminonaphthalene Iodide-Passivated 2D/3D Perovskite Solar Cells

Engineering multidimensional two-dimensional/three-dimensional (2D/3D) perovskite interfaces as light harvesters has recently emerged as a potential strategy to obtain a higher photovoltaic performance in perovskite solar cells (PSCs) with enhanced environmental stability. In this study, we utilized the 1,5-diammonium naphthalene iodide (NDAI) bulky organic spacer for interface modification in 3D perovskites for passivating the anionic iodide/uncoordinated Pb2+ vacancies as well as facilitating charge carrier transfer by improving the energy band alignment at the perovskite/HTL interface. Consequently, the NDAI-treated 2D/3D PSCs showed an enhanced open-circuit voltage and fill factor with a remarkable power conversion efficiency (PCE) of 21.48%. In addition, 2D/3D perovskite devices without encapsulation exhibit a 77% retention of their initial output after 1000 h of aging under 50 ± 5% relative humidity. Furthermore, even after 200 h of storage in 85 °C thermal stress, the devices maintain 60% of their initial PCE. The defect passivation and interface modification mechanism were studied in detail by UV vis absorption, photoluminescence spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), solid-state NMR, space-charge-limited current (SCLC) mobility measurement, and impedance spectroscopy. This study provides a promising path for perovskite surface modification in slowing their degradation against external stimuli, providing a future direction for increasing the perovskite device efficiency and durability.