Prolonged Carrier Lifetime Research Articles

Realization of electrolyte interface effect on Bi2Te3 implanted flake-like ZnO thin films for understanding the highly stable PEC water splitting under simulated solar light and visible light

This study aimed to rationally design the novel Bi2Te3 implanted ZnO (Bi2Te3@ZnO) thin films using simultaneous RF and DC magnetron sputtering technique. Herein, we explored the electrolyte interface effect (0.1 M of KOH, KCl, Na2SO3 and Na2SO4) on ZnO and Bi2Te3@ZnO towards highly stable PEC water splitting activity for the first time. Specifically, morphological evolution and electrolyte ion diffusion properties play a crucial role in realizing the prolonged charge carrier lifetime. Moreover, Bi2Te3@ZnO is highlighted with unique nanocone-shaped morphology compared to flake-like ZnO. Also, constructive interfacial interaction was observed between Bi2Te3 and ZnO. As a result, Bi2Te3@ZnO demonstrated superior and highly stable photocurrents in the KOH electrolyte compared to KCl, Na2SO3 and Na2SO4 electrolytes. Precisely, Bi2Te3@ZnO triumphed highly stable photocurrents about 7.93 × 10–4 A cm−2 compared to ZnO (6.02 × 10–4) at +0.4 V under solar light in KOH electrolyte. Accordingly, Bi2Te3@ZnO achieved remarkable photoconversion efficiency (η) about 0.65 %, which is enabled by the strengthened intimate interaction between Bi2Te3 and ZnO. Furthermore, we compared the PEC activity under visible light (UV cut-off solar light). These results highlighted that the photoconversion efficiency difference between Bi2Te3@ZnO and ZnO (about 4 times) under visible light is relatively higher than solar light (1.3 times) in KOH. Thus, we proposed different charge carrier generation mechanisms of Bi2Te3@ZnO under solar and visible light. Therefore, intimate interfacial interaction, surface modification, ion diffusion and photoelectrode-electrolyte interaction are key parameters to enhance the PEC activity. Overall, rational design of the transition metal oxide/thermoelectric material interface using Bi2Te3@ZnO composite paves a new path towards highly stable photoanode during PEC water splitting activity in the KOH electrolyte environment.

Organic Dye Passivation for High‐Performance All‐Inorganic CsPbI1.5Br1.5 Perovskite Solar Cells with Efficiency over 14%

AbstractAll‐inorganic perovskite solar cells (PSCs) have recently received growing attention as a promising template to solve the thermal instability of organic–inorganic PSCs. However, the thermodynamic phase instability and relatively low device efficiency pose challenges. Herein, highly efficient and stable CsPbI1.5Br1.5 compositional perovskite‐based inorganic PSCs are fabricated using an organic dye, fluorescein isothiocyanate (FITC), as a passivator. The carboxyl and thiocyanate groups of FITC not only minimize the trap states by forming interactions with the under‐coordinated Pb2+ ions but also significantly increase the grain size and improve the crystallinity of the perovskite films during annealing. Consequently, perovskite films with superior optoelectronic properties, prolonged carrier lifetime, reduced trap density, and improved stability are obtained. The resulting device yields a champion efficiency of 14.05% with negligible hysteresis, which presents the highest reported efficiency for inorganic CsPbI1.5Br1.5 solar cells reported thus far. In addition, FITC can be generally adopted as attractive passivator to improve the performance of CsPbI2Br‐ and CsPbIBr2‐based PSCs. Furthermore, with a comprehensive comparison of mixed‐halide inorganic perovskites, it is demonstrated that CsPbI1.5Br1.5 compositional perovskite is a promising candidate with the optimal halide composition for high‐performance inorganic PSCs.

Atomic Sandwiched p‐n Homojunctions

AbstractSemiconductor p‐n junctions have been explored and applied in photoelectrochemical (PEC) water splitting, but serious carrier recombination and sluggish oxygen evolution reaction (OER) dynamics have demanded further progress in p‐n junction photoelectrode design. Here, via a controllable NH3 treatment, we construct sandwiched p‐n homojunctions in three‐unit‐cells n‐type SnS2 (n‐SnS2) nanosheet arrays using nitrogen (N) as acceptor dopants. The optimal N‐doped n‐SnS2 (pnp‐SnS2) with such unique structure achieves a record photocurrent density of 3.28 mA cm−2, which is 21 times as high as that of n‐SnS2 and the highest value among all the SnS2 photoanodes reported so far. Moreover, the stoichiometric O2 and H2 evolution from water was achieved with Faradaic efficiencies close to 100 %. The superior performance could be attributed to the facilitated electron–hole separation/transfer, accelerated surface OER kinetics, prolonged carrier lifetime, and improved structural stability.

Atomic Sandwiched p-n Homojunctions.

Semiconductor p-n junctions have been explored and applied in photoelectrochemical (PEC) water splitting, but serious carrier recombination and sluggish oxygen evolution reaction (OER) dynamics have demanded further progress in p-n junction photoelectrode design. Here, via a controllable NH3 treatment, we construct sandwiched p-n homojunctions in three-unit-cells n-type SnS2 (n-SnS2 ) nanosheet arrays using nitrogen (N) as acceptor dopants. The optimal N-doped n-SnS2 (pnp-SnS2 ) with such unique structure achieves a record photocurrent density of 3.28 mA cm-2 , which is 21 times as high as that of n-SnS2 and the highest value among all the SnS2 photoanodes reported so far. Moreover, the stoichiometric O2 and H2 evolution from water was achieved with Faradaic efficiencies close to 100 %. The superior performance could be attributed to the facilitated electron-hole separation/transfer, accelerated surface OER kinetics, prolonged carrier lifetime, and improved structural stability.

Isotopic Exchange Extends Charge Carrier Lifetime in Metal Lead Perovskites by Quantum Dynamics Simulations.

One may expect that isotopic exchange has no influence on charge carrier lifetime and perovskite solar cell performance because isotopic effects do not affect the fundamental electronic structure of materials. Experiments defy this expectation. By performing nonadiabatic (NA) molecular dynamics simulations, we demonstrate that hydrogen and deuterium exchange significantly enhances the excited-state lifetime and stability of CH3NH3PbI3. Replacing lighter hydrogen with heavier deuterium suppresses the collective motions of organic and inorganic components, thus enhancing lattice stiffness and decreasing the NA coupling. Isotopic exchange further reduces NA coupling by localizing electron wave functions for separation of electrons and holes, which beats the extended coherence time, slowing down nonradiative electron-hole recombination from CH3ND3PbI3 to CD3ND3PbI3 with respect to the pristine system. The unchanged fundamental electronic structure together with the prolonged carrier lifetime and enhanced stability rationalize the improvement of the deuterated CH3NH3PbI3 solar cells. Our work provides valuable insights into isotope effects for the design of high-performance perovskite photovoltaic and optoelectronic devices.

Ag3PO4/g-C3N4 Z-scheme composites with enhanced visible-light-driven disinfection and organic pollutants degradation: Uncovering the mechanism

A novel Z-scheme Ag3PO4/g-C3N4 heterostructures was constructed successfully for Escherichia coli inactivation and organic pollutants degradation under visible light irradiation. The Ag3PO4(8)/g-C3N4 possessed the highest photocatalytic effect with more than 7 log of live Escherichia coli (E. coli) totally inactivated within 75 min and complete BPA degradation within 180 min. By mimicking the components of natural water individually, humic acid (HA) and inorganic anion were found to deeply affected the photocatalytic disinfection activity. Moreover, the Ag3PO4(8)/g-C3N4 revealed significantly boosted visible-light-driven photocatalytic performance for ciprofloxacin and sulfadiazine degradation. The satisfying degradation effects of bisphenol A in nature waters were also obtained. The improved photocatalytic efficiency of Ag3PO4/g-C3N4 may be attributed to the formation of Z-scheme heterostructure structure and matching valence band and conduction band, resulting in rapid separation of photo-induced carrier, enhanced electronic transport capacity and prolonged carrier lifetime. The possible mechanism was studied using radical quenching tests and electron spin resonance, suggesting that the hole, electron and hydroxyl radical were the paramount active species during Escherichia coli disinfection. This work pioneers a novel strategy for upgrading the photocatalytic disinfection and degradation capacities of g-C3N4 based catalysts.

Topological transformation of bismuth vanadate into bismuth oxychloride: Band-gap engineering of ultrathin nanosheets with oxygen vacancies for efficient molecular oxygen activation

• An in-situ topological transformation way is proposed to synthesize ultrathin BiOCl. • BiOCl inherits the nanosheet structure and oxygen vacancies of the BiVO 4 precursor. • The oxygen vacancies endow BiOCl nanosheets with improved light-harvesting ability. • The oxygen vacancies promote charge carrier separation and prolong carrier lifetime. • 5.0 and 3.5 times increase in CIP removal rate and O 2 − yield are achieved in BiOCl. Herein, a facile in-situ topological transformation where BiVO 4 nanosheets (NS) with open instead of closed and inert surface are used as template and original material for the preparation of ultrathin BiOCl NS is proposed. The BiOCl NS developed in this work not only inherits the two-dimensional nanosheet structure of the BiVO 4 precursor, but also exhibits improved light-harvesting ability in the meantime as a result of the retention of oxygen vacancies during the topological transformation. The defect state mediated by oxygen vacancies under the conduction band endows BiOCl a narrower forbidden band width as compared to its bulk counterpart, which extends its light absorption range from ultraviolet to visible light region. More importantly, oxygen vacancies can also act as cocatalyst to accept photogenerated electrons excited from the valence band of BiOCl, which greatly suppresses the recombination of electron-hole pairs and prolongs the carrier lifetime, thereby promoting the activation of molecular oxygen into superoxide radicals ( O 2 − ) under visible light irradiation. As expected, the optimal BiOCl-3 NS exhibits a 2.2-fold increase in the yield of O 2 − radicals compared with bulk-BiVO 4 . Furthermore, a large amount of free H + in the waste acid wastewater can be tightly adsorbed with the terminal oxygen atoms of the (0 0 1) facet of BiOCl to compensate for its dangling bonds, which inhibits the crystal growth along the c axis, leaving highly reactive (0 0 1) facets as the dominant facets. Thanks to these merits, BiOCl-3 displays the highest photocatalytic performance towards ciprofloxacin (CIP) degradation among all samples, with the corresponding degradation rate of 4.51 times higher than that of the bulk-BiVO 4 , and the apparent quantum efficiency of 0.411%. Moreover, the as-developed BiOCl NS has excellent stability even after five successive cycles, with no significant changes in photocatalytic activity and structure, showing its good potential in practical applications.

Interlayer Polarization Explains Slow Charge Recombination in Two-Dimensional Halide Perovskites by Nonadiabatic Molecular Dynamics Simulation.

Two-dimensional (2D) perovskites for applications in photovoltaics and optoelectronics are attracting a great deal of research interest. The nonradiative electron-hole (e-h) recombination is the major efficiency loss channel. Herein, we report a study of the thickness dependence of the e-h recombination dynamics in diamine-based 2D perovskite via ab initio NAMD. For multilayer structures, due to the emergence of spontaneous interlayer electric polarization, which is induced by the collective and correlated reorientation of methylammonium molecules, the electron and hole at the band edges are localized in different inorganic layers, suppressing the e-h recombination. Furthermore, a broad range of phonon excitation also inspired rapid pure dephasing related to the microscopic origin for longer recombination times. The combination of the two effects leads to the observation of a prolonged carrier lifetime in multilayer 2D perovskites, which is essential to understanding the nonradiative e-h recombination mechanism in such materials.

Vectorial carriers interfacial migration of Cd1-xZnxS heterophase junctions for visible-light water splitting

Twin structure in Cd1-xZnxS solid solution based on sphalerite/wurtzite (ZB/WZ) heterophase junction is considered as a quite promising approach to enhance the charge separation efficiency and inhibit the charge recombination during the photocatalytic process. Herein, Cd1-xZnxS nanocrystals based on ZB/WZ heterophase junction with different molar ratios of Cd/Zn were synthesized by one-step solvothermal process. XRD analysis and HRTEM images verified the formation of nano-twin structures in the Cd0·6Zn0·4S solid solution. Photoluminescence (PL) spectra, time-resolved photoluminescence (TRPL) spectra, Electrochemical impedance spectroscopy (EIS) test and Photocurrent response revealed that the recombination of photogenerated charge carriers has been reduced due to the presence of ZB/WZ heterophase junction. The experimental results showed that the photocatalytic activity of Cd0·6Zn0·4S without noble metal load was the best under visible light irradiation, and the hydrogen production efficiency was up to 472 μmol h−1 and an apparent quantum efficiency of 9.8% at 420 nm. The periodic type-Ⅱ staggered energy band arrangement formed between ZB and WZ phases can orientate the photoinduced electrons and holes to ZB and WZ regions, respectively, and redox reactions can occur on the surface. Meanwhile, Cd0·6Zn0·4S exhibited good stability for hydrogen production. The result provides an available progress for the development of photocatalytic mechanism in heterophase junction between ZB and WZ phases, leading to the vectorial interfacial transfer of photogenerated e−/h+ pairs and prolonged carrier lifetime which can effectively enhance the photocatalytic reactivity.

Vertical graphene nano-antennas for solar-to-hydrogen energy conversion

Effective separation and transfer of photogenerated charge carriers are common issues in solar energy conversion. Strong localized electric fields near functional nanostructures reduce charge recombination and boost energy efficiency and photocatalytic activity. However, common metal-based photocatalytic systems on conducting supports under-utilize infrared (IR) light energy, and suffer from unsatisfactory interface quality and stability, as well as high complexity and cost. Here we develop a photocatalytic nano-antennas simultaneously featuring localized field-enhancement in IR, high electric conductivity, and interface stability. In the nano-antennas, plasma-made all-carbon vertical graphene nanopetals (GPs) are covalently interfaced with high-performance metal-free semiconducting graphitic carbon nitride (g-C3N4) photocatalyst. The photo-induced force microscopy is used to obtain real-space images of localized electric field enhancement in the near-IR and mid-IR ranges along the vertically standing ultra-sharp GP edge nano-antennas. The photocurrent, electrochemical impedance spectra, and time-resolved photoluminescence spectra confirm that the GP edge nano-antennas significantly enhance the photogenerated charge carrier separation, accelerate carrier migration, and prolong carrier lifetime. We also demonstrate the scalability of production of the petal edge nano-antennas. The unique graphene nanoarchitecture offer exotic spectral properties, which are essential for many large-scale solar energy harvesting applications such as photocatalysis, photovoltaics, and solar-thermal water desalination and purification.

Direct Growth of Pyramid‐Textured Perovskite Single Crystals: A New Strategy for Enhanced Optoelectronic Performance

AbstractEven though there have been a few reports of substrate surface texturing of thin film perovskite solar cells to enhance their light trapping, there has been no direct texturing of the perovskite material, let alone perovskite single crystals (SCs). Herein, a method to prepare a pyramid‐structured perovskite CH3NH3PbX3 (CH3NH3+ = MA, X = I, Br) SC surface with minimized light reflection and maximized incident light harvesting is reported. Specifically, a hard template is used to directly transfer the pyramidal texture onto the MAPbX3 SC during its growth. A well‐shaped pyramidal texture is formed on the single‐crystal surface leading to improved light trapping. The textured MAPbBr3 SC shows good crystallinity, prolonged carrier lifetime, and improved carrier mobility. Furthermore, the photodetector made from the textured SC shows enhanced responsivity of 321 A W−1 and external quantum efficiency of 7191%, about two times higher than that of a control device. This method may be used to directly fabricate desired textures on general single crystal surfaces.

Water hyacinth derived carbon quantum dots and g-C3N4 composites for sunlight driven photodegradation of 2,4-dichlorophenol

Carbon dots (CDs) were successfully derived from water hyacinth leaves and the binary composite was achieved by incorporating CDs with g-C3N4 through hydrothermal treatment. The average particle size of CDs was found to be 3.1 nm and a blue-green fluorescence was emitted under the UV light irradiation. Both of the composites loaded with 20 wt.% (20CDs/g-C3N4) and 40 wt.% (40CDs/g-C3N4) of CDs achieved the highest degradation efficiency of 2,4-dichlorophenol (2,4-DCP) with 1.7 times higher than that of pure g-C3N4. This work successfully improved the properties of g-C3N4 by elongating the lifetime of photogenerated electrons and widening the visible light response. Both of 20CDs/g-C3N4 and 40CDs/g-C3N4 recorded the highest photocatalytic performance in degrading 2,4-DCP with degradation rate constant of 0.0194, and 0.0186 min−1, respectively. This is contributed by the prolonged charge carrier lifetime in 20CDs/g-C3N4; good visible light absorption and high specific surface area in 40CDs/g-C3N4. For the scavenger test, hole (h+) and superoxide radical (·O2−) were acknowledged as the key active species in photocatalysis.

Improving the performance of ultra-flexible perovskite photodetectors through cation engineering

High performance ultra-flexible lightweight perovskite photodetectors have promising applications on a variety of substrates, including those used on unmanned aerial vehicles. Herein, we report on a facile method to improve the performance of perovskite photodetectors on flexible ultrathin (50 μm) polyimide substrates by tuning the composition with different ratios of cations. In the presence of lead thiocyanate, the introduction of a certain amount of formamidinium could sufficiently enhance the quality of methylammonium lead triiodide perovskite film, with prolonged carrier lifetime. A perovskite photodetector with a response time of ton = 89 ms and toff = 47 ms is achieved with a very simple device architecture. In addition, our flexible photodetectors maintain good performance after rigorous folding and bending, demonstrating excellent mechanical properties, which could be very useful for a variety of applications.

PVP Treatment Induced Gradient Oxygen Doping in In2S3 Nanosheet to Boost Solar Water Oxidation of WO3 Nanoarray Photoanode

AbstractThe photoelectrochemical performance of the WO3 photoanode is limited by the severe charge recombination in the bulk phase and at the WO3/electrolyte interface. Herein, In2S3 nanosheets are integrated onto the surface of the WO3 nanowall array photoanode, followed by a facile polyvinylpyrrolidone (PVP) solution treatment. The PVP treatment results in sulfur vacancies and a gradient oxygen doping into In2S3 from surface to interior, which induces the formation of a gradient energy band distribution. The gradient band structured In2S3 and type II band alignment at the WO3/In2S3 interface simultaneously create a channel that favors photogenerated electrons to migrate from the surface to the conductive substrate, thereby suppressing bulk carrier recombination. Meanwhile, the sulfur vacancies and oxygen doping contribute to increased charge carrier concentration, prolonged carrier lifetime, more active sites, and small interfacial transfer impedance. As a consequence, the PVP treated WO3/In2S3 heterostructure photoanode exhibits a significantly enhanced photocurrent of 1.61 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE) and negative onset potential of 0.02 V versus RHE.

Improved Performance of Carbon Electrode Perovskite Solar Cells Using Urea Treatment in Two‐Step Processing

AbstractPerovskite solar cell has made a steady research progress with superior photovoltaic power conversion efficiency (PCE) over 25%. The quality of perovskite film is a key factor affecting device efficiency. Lewis bases such as urea, DMSO and thiourea etc. have been applied in perovskite precursor solutions for one step processing to effectively control the film morphology. Herein, we report urea treatment in a two‐step processing for obtaining high quality methylammonium lead triiodide perovskite (CH3NH3PbI3) film, which is accomplished by immersing the PbI2 film into the mixture solution of urea/methylammonium iodide (MAI). The optimized urea concentration in the MAI solution is 0.4 mg/mL, leading to larger‐sized and better crystalline perovskite grains than that without urea additive. The main function of the urea additive is the formation of the adduct MAI⋅PbI2⋅O=C(NH2)2, retarding the crystallization process of the perovskite film. The steady‐state and time‐resolved photoluminescence measurements revealed that perovskite CH3NH3PbI3 grown using optimized concentration of urea has prolonged carrier lifetime and reduced carrier recombination. Finally, the carbon‐based perovskite solar cells fabricated from the optimal urea concentration of 0.4 mg/mL achieved the enhanced photovoltaic performance with the highest PCE of 13.10% and an average value of 11.34%, in comparison to devices without urea treatment exhibiting an average PCE of only 8.67%.

All-Solid-State Z-Scheme α-Fe2O3/Amine-RGO/CsPbBr3 Hybrids for Visible-Light-Driven Photocatalytic CO2 Reduction

Summary Lead halide perovskite (PVK) has been deemed as a promising photocatalyst alternative because of its remarkable photoelectrical properties; however, the severe charge recombination has limited its catalytic activity. Herein, we report a PVK-based Z-scheme heterojunction, α-Fe2O3/Amine-RGO/CsPbBr3, for high-efficiency CO2 reduction in the presence of H2O. By delicately controlling the interfacial interaction, effective Z-scheme electron transfer from α-Fe2O3 to CsPbBr3 is built, leading to boosted charge separation and prolonged carrier lifetime, as confirmed by electron spin resonance (ESR), transient absorption (TA) spectra, etc. The impactful spatial separation of photo-generated carriers in Z-scheme system finally enables an 8.3-fold enhancement in photocatalytic performance as compared to CsPbBr3. A stable product yield of 469.16 μmol g−1 and an electron consumption yield of 3,132.46 μmol g−1 are achieved. This work is expected to provide deep insights into boosting the photocatalytic performance of PVK by modulating the charge carrier dynamics.

Precise control of PbI2 excess into grain boundary for efficacious charge extraction in off-stoichiometric perovskite solar cells

Excess PbI2 has been widely introduced in halide perovskite precursor solution to passivate the grain boundary defects in high efficient perovskite solar cells (PSCs). However, the passivation effect is highly sensitive to the PbI2 content and overmuch PbI2 affects the crystalline growth and charge transport. We report here a precious control of excess PbI2 into perovskite grain boundaries by methylamine treatment for efficacious defects passivation and charge extraction. The crystallization of the deposited perovskite films was carefully evaluated and the charge recombination dynamics were systematically analyzed through time-resolved photoluminescence spectroscopy, space charge limited current, electrochemical impedance spectroscopy and Mott-Schottky analysis. The precise PbI2 introduction to the grain boundaries results in a significantly lower defect state density, efficient charge extraction and prolonged carrier lifetime, causing a notable increase of short-circuit current density and negligible hysteresis in the corresponding device. Our work demonstrates a reliable method to alleviate the rigorous tolerance of PbI2 excess in high efficient PSCs.

Quantum confinement-induced enhanced nonlinearity and carrier lifetime modulation in two-dimensional tin sulfide

Abstract Two-dimensional tin sulfide (SnS), as a black phosphorus-analogue binary semiconductor, has received considerable attention in photonics and optoelectronics. Herein, the third-order nonlinearity susceptibility Im χ3 is enhanced from −(6.88 ± 0.10) × 10−14 esu to −(15.90 ± 0.27) × 10−14 esu by the size-related quantum confinement in layered SnS nanosheets. Due to the energy level alignment, a phonon-bottleneck effect is observed, which leads to a prolonged carrier lifetime. These results provide a platform for actively tuning the linear and nonlinear optics, and pave the way for designing SnS-based tunable and anisotropic optoelectronic devices.

In Situ Defect Passivation with Silica Oligomer for Enhanced Performance and Stability of Perovskite Solar Cells

AbstractPerovskite solar cells (PVSCs) have achieved excellent power conversion efficiency (PCE) but still suffer from instability issues. Defect passivation is an important route to simultaneously increase the efficiency and stability of PVSCs. Here, a strategy of incorporating silica oligomer in perovskite films for surface and grain boundary defect passivation is reported. Silica oligomer passivation agent (PA) is in situ formed through hydrolysis and condensation reaction of tetraethyl orthosilicate additive in perovskite precursor. The passivation mechanism is elucidated by density functional theory calculation, revealing stable chelating interaction and hydrogen bond interaction between PA and perovskite. Spectroscopic and electrical characterizations demonstrate that silica oligomer can enlarge grain sizes, prolong carrier lifetime, enhance charge carrier dynamics, and reduce trap state densities in perovskite films. Planar PVSCs with passivation achieve a highly improved PCE of 19.64% with a stabilized efficiency of 18.81%. More importantly, unencapsulated perovskite devices with passivation retain nearly 90% of original efficiency after 1000 h storage under ambient condition and sustained 87% of initial performance after high‐temperature (120 °C) thermal accelerated aging, showing highly enhanced moisture and thermal stability. Therefore, the present study provides a pathway to the future design and optimization of PVSCs with higher efficiency and greater stability.

2D multilayered perovskites based on 4-chlorophenylethylamine for solar cell application

Two-dimensional layered organic-inorganic perovskite hybrids have attracted increasing attention due to their outstanding moisture resistance and promising optoelectronic properties. However, the photovoltaic performance in solar cells is still a huge challenge for two-dimensional perovskite films. With the aim to improve the efficiency of 2D perovskite solar cells, the new (ClC6H4C2H4NH3)2MAn−1PbnI3n+1 perovskite family (abbreviated as (CPEA)2MAn−1PbnI3n+1) are synthesized by a simple one-step hot-casting method in this study. It is found that the variation of n value (n = 3–6) has great influence on the microstructure, grain size, charge mobility, trap density and photovoltaic performance of the 2D (CPEA)2(MA)n−1PbnI3n+1. Due to the best film quality and prolonged carrier lifetime, the (CPEA)2MA4Pb5I16 (n = 5) perovskite solar cell exhibits a highest efficiency of 11.86%, with a Voc of 0.989 V, a Jsc of 19.92 mA/cm2 and FF of 60%, respectively. It is anticipated that our approach to explore new organic spacer cations in 2D perovskites may pave the way for their application with high performance.