Highly Efficient 2D/3D Hybrid Perovskite Solar Cells via Low‐Pressure Vapor‐Assisted Solution Process

Abstract

The fabrication of multidimensional organometallic halide perovskite via a low-pressure vapor-assisted solution process is demonstrated for the first time. Phenyl ethyl-ammonium iodide (PEAI)-doped lead iodide (PbI ) is first spin-coated onto the substrate and subsequently reacts with methyl-ammonium iodide (MAI) vapor in a low-pressure heating oven. The doping ratio of PEAI in MAI-vapor-treated perovskite has significant impact on the crystalline structure, surface morphology, grain size, UV-vis absorption and photoluminescence spectra, and the resultant device performance. Multiple photoluminescence spectra are observed in the perovskite film starting with high PEAI/PbI ratio, which suggests the coexistence of low-dimensional perovskite (PEA MA Pb I ) with various values of n after vapor reaction. The dimensionality of the as-fabricated perovskite film reveals an evolution from 2D, hybrid 2D/3D to 3D structure when the doping level of PEAI/PbI ratio varies from 2 to 0. Scanning electron microscopy images and Kelvin probe force microscopy mapping show that the PEAI-containing perovskite grain is presumably formed around the MAPbI perovskite grain to benefit MAPbI grain growth. The device employing perovskite with PEAI/PbI = 0.05 achieves a champion power conversion efficiency of 19.10% with an open-circuit voltage of 1.08 V, a current density of 21.91 mA cm , and a remarkable fill factor of 80.36%.

Air‐Stable Highly Crystalline Formamidinium Perovskite 1D Structures for Ultrasensitive Photodetectors

“…In contrast, layered perovskites with strong blueshifted exciton resonance and periodic diffraction peaks with 2θ ranging from 5 o to 30° can be observed when the molar ratio of PEA + in wires is higher than 22 mol%. These results demonstrate that the PEA + binding to the surface of FAPbI 3 can effectively stabilize the α‐phase (Figure S17, Supporting Information) 39–41…”

Stable, Efficient Red Perovskite Light‐Emitting Diodes by (α, δ)‐CsPbI3 Phase Engineering

“…Meanwhile, some weak peaks at short wavelength (≈515 and ≈561 nm) gradually appear. Here, these new peaks should be ascribed to the emission of (NEA) 2 PbI 4 on the α‐CsPbI 3 grain surface . However, even in the sample with NEA concentration being 70%, these new peaks can be negligible compared to the dominant characteristic peak of α‐CsPbI 3 .…”

Structural Damage of Two-Dimensional Organic–Inorganic Halide Perovskites

“…Two-dimensional (2D) organic-inorganic halide perovskites have attracted significant research interests owing to their wide tunability and excellent optical/electronic properties [1,2]. The efficiency of 2D perovskite solar cells has been increasingly improved and perovskite solar cells show tremendous advantages over silicon solar cells [3][4][5]. The perovskite bulk structure has the general formula of ABX 3 , where the A-site cations are normally inorganic alkali ions Cs + , Rb + , or can be substituted by short organic cations CH 3 NH 3 + (methylammonium, MA) or CH(NH 2 ) 2 + (formamidinium, FA).…”

“…The efficiency of 2D perovskite solar cells has been increasingly improved and perovskite solar cells show tremendous advantages over silicon solar cells [3][4][5]. The perovskite bulk structure has the general formula of ABX 3 , where the A-site cations are normally inorganic alkali ions Cs + , Rb + , or can be substituted by short organic cations CH 3 NH 3 + (methylammonium, MA) or CH(NH 2 ) 2 + (formamidinium, FA). The BX 3 are octahedrons composed of Pb 2+ (or Sn 2+ ) and halide ions.…”

“…The perovskite bulk structure has the general formula of ABX 3 , where the A-site cations are normally inorganic alkali ions Cs + , Rb + , or can be substituted by short organic cations CH 3 NH 3 + (methylammonium, MA) or CH(NH 2 ) 2 + (formamidinium, FA). The BX 3 are octahedrons composed of Pb 2+ (or Sn 2+ ) and halide ions. In contrast to the bulk perovskites, 2D halide perovskites are usually formed in organic-inorganic hybrid phases, with separated octahedral [BX 6 ] 4− layers jointed by long organic chains, such as n-butylammonium (n-BA + ), bithiophene (2T), and tetrathiophene (4T).…”