Electron Transport Layer Research Articles

Controllable Heavy n–type Behaviours in Inverted Perovskite Solar Cells with Non‐Conjugated Passivants

AbstractInterfacial issues between the perovskite film and electron transport layer greatly limit the efficiency and stability of inverted (p‐i‐n) perovskite solar cells (PSCs). Despite organic ammonium passivants have been widely established as interfacial layers, they failed to improve electron extraction. Here, we reported that the heavy n‐type characteristics in a low band gap perovskite film could be modulated by incorporating non‐conjugated ammonium passivants with strong electron‐withdrawing abilities. This resulted in a significant enhancement of electron extraction in the heavily n‐type doped perovskite. The passivant‐treated PSCs exhibited a power conversion efficiency of 25.74 % with an excellent fill factor of 85.4 % and a high open‐circuit voltage of 1.166 V, which are significantly higher than that of the control device. The unencapsulated devices maintained 88 % of their initial PCEs after 1,200 hours at 85 °C.

Stabilizing Wide‐Bandgap Perovskite with Nanoscale Inorganic Halide Barriers for Next‐Generation Tandem Technology

AbstractWide‐bandgap (WBG) perovskite solar cells (PSCs) play a crucial role in advancing perovskite‐based tandem solar cells. In WBG perovskite films, grain boundary (GB) defects are the main contributors to open‐circuit voltage (VOC) deficits and performance degradation. This report presents an effective strategy for passivating GBs by incorporating an inorganic protective layer and reducing the density of GBs in perovskite films. This is achieved by integrating potassium thiocyanate (KSCN) into I‐Br mixed halide WBG perovskites. It is reported for the first time that the incorporation of KSCN creates band‐shaped barriers along the GBs. In addition, KSCN enlarges the grains of perovskite film. Elemental and structural analyses reveal that these barriers are composed of potassium lead halide. Incorporating KSCN significantly enhances the fill factor and VOC of WBG single‐junction PSCs by reducing trap density. This results in high power conversion efficiencies of 19.22% (bandgap of 1.82 eV), 20.45% (1.78 eV), and 21.54% (1.70 eV) with a C60/bathocuproine electron transport layer, and 18.51% (1.82 eV) with a C60/SnO2. Furthermore, both operational and shelf stabilities are significantly improved due to reduced light‐induced halide segregation. By using inorganic‐halide‐passivated WBG sub‐cells, a monolithic all‐perovskite tandem solar cell with an efficiency of 27.04% is demonstrated.

Efficient and Stable Quantum‐Dot Light‐Emitting Diodes with Trilayer PIN Architecture

AbstractAlthough the performance of quantum dot light‐emitting diodes (QLEDs) has been greatly improved in recent years, the multilayer device structure has become increasingly complex, limiting the practical application of QLEDs. Here, a novel trilayer PIN QLED with only three functional layers, which are Spiro‐OMeTAD:TFB bulk‐heterojunction (BHJ) hole transport layer (HTL), quantum‐dot emitting layer and ZnMgO electron transport layer is demonstrated. Due to the enhanced hole injection capability and suppressed electron leakage of Spiro‐OMeTAD:TFB BHJ HTL, the trilayer PIN QLED can show an excellent external quantum efficiency (EQE) of 25.1% and an impressive brightness of 299300 cd m−2 at only 8 V, which are significantly higher than those of conventional QLED. Moreover, the device stability is also remarkably improved due to the mitigation of hole accumulation and removal of unstable PEDOT:PSS. By using liquid alloy EGaIn as cathode, a fully solution‐processed vacuum‐free trilayer PIN QLED with a higher EQE of 27.3% can be further realized. The developed trilayer PIN QLEDs, with better performance and fewer functional layers, can promote the commercialization of QLED technology.

Atomic Layer Deposition of ZnO on CsPbBr3 Perovskite Nanocrystals: Surface-Dependent Mechanistic Insights.

In this study, we investigate the atomic layer deposition (ALD) process on all-inorganic CsPbBr3 perovskite nanocrystals (PNCs) to introduce an inorganic electron transport layer (ETL) in light-emitting diode (LED) devices. Two types of CsPbBr3 PNCs were synthesized with oleate (OA) and oleylammonium (OLA) ligands on the surface. We found that CsPbBr3 PNCs with Cs oleate surfaces experienced severe photoluminescence (PL) quenching after the ALD process, while those with oleylammonium bromide surfaces did not show any significant PL drop. Transmission electron microscopy and X-ray photoelectron spectroscopy revealed that significant Pb metal formation and Ruddlesden-Popper planar faults, linked to uncoordinated Pb2+ ion defects, were generated in CsPbBr3 PNCs terminated with Cs oleate after ALD ZnO. Finally, we fabricated LEDs using PNCs with an ALD ZnO process to introduce inorganic ZnMgO nanoparticles as the ETL. The devices processed with ALD exhibited superior luminance and external quantum efficiency compared to those without the ALD process. This research provides crucial insights into the surface-dependent chemistry of PNCs and the surface-dependent performance of perovskite-based optoelectronic devices.

Comparing the Efficacies of Electrospun ZnO and TiO2 Nanofibrous Interlayers for Electron Transport in Perovskite Solar Cells

ZnO and TiO2 are both well-known electron transport materials. Their comparison of performance is considered advantageous and novel. Therefore, a viable electrospinning route was considered for the development of highly polycrystalline TiO2 and ZnO nanofibers as an electron transport material (ETM) for perovskite solar cells. The materials were well-characterized in terms of different analytical techniques. The X-ray diffraction detected polycrystalline structural properties corresponding to TiO2 and ZnO. Morphological analysis by scanning electron microscopy revealed that the nanofibers are long, uniform, and polycrystalline, having a diameter in the nanometer range. Optoelectronic properties showed that TiO2 and ZnO exhibit absorption values in the ultraviolet and visible ranges, and band gap values for TiO2 and ZnO were 3.3 and 3.2 eV, respectively. TiO2 bandgap and semiconductor nature were more compatible with Electron Transport Layer (ETL) compared to ZnO. Electrical studies revealed that TiO2 nanofibers have enhanced values of conductivity and sheet carrier mobility compared to ZnO nanofibers. Therefore, higher photovoltaic conversion efficiency was achieved for TiO2 nanofibers (10.4%) compared to ZnO (8.5%).

Tailor‐Made Buffer Materials: Advancing Uniformity and Stability in Perovskite Solar Cells

AbstractAlong with the growing popularity of the p‐i‐n structure, bathocuproine (BCP) is increasingly recognized as a crucial buffer layer between the electron transport layer and electrode with the role of mitigating Schottky contact and enhancing performance. However, the chemical structure and role of its functional groups have not been thoroughly elucidated. This study introduces a novel modification of BCP in perovskite solar cells (PSCs) by altering functional groups to optimize their geometrical molecular structures and electronic properties. The substitution of aromatic phenyl and p‐tolyl groups to 2,9‐position on the BCP is highly effective in increasing the planarity of the conjugated backbone and protecting the reactive nitrogen atoms of the phenanthroline core, thereby improving charge transport and device stability. Experimental analyses, including electrostatic force microscopy, impedance spectroscopy, and photoluminescence, reveal that the modified BCP significantly enhances charge transport, reduces recombination losses, and markedly improves the structural stability of PSCs, leading to prolonged device lifetimes. The findings highlight the potential of structurally optimized BCP derivatives as a critical component in advancing high‐efficiency and durable PSCs.

Toward Commercial-Scale Perovskite Solar Cells: The Role of ALD-SnO2 Buffer Layers in Performance and Stability.

Hybrid organic-inorganic perovskite solar cells (PSCs) have shown significant potential in photovoltaic applications due to their superior optoelectronic properties. However, the conventional electron transport layer (ETL) of C60 in PSCs poses challenges such as incomplete coverage and metal diffusion, leading to reduced performance and stability. This work explores the efficacy of atomic layer deposition (ALD) of SnO2 as an interlayer between C60 and electrode to enhance the performance and stability of devices. Devices with varying SnO2 thicknesses were fabricated, revealing that a 15 nm ALD-SnO2 layer optimally improved the power conversion efficiency (PCE) to 23.85%, compared to the 22.86% achieved with a BCP layer. Moreover, the SnO2-based devices exhibited superior open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor (FF). Modules (30 × 30 cm) with ALD-SnO2 demonstrated notable enhancements in efficiency and uniformity, suggesting the potential for scalable commercial applications. Photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) analyses confirmed the improved charge extraction and reduced recombination with the SnO2 buffer layer. This research indicates that ALD-SnO2 is a promising interlayer candidate for PSCs, providing a pathway toward higher efficiency and stability in perovskite solar technology.

Optimizing non-toxic (CH3NH3)3Bi2I9 perovskite solar cells by SCAPS-1D

Abstract Low-dimensional bismuth-based perovskite solar cells (PSCs) have demonstrated some benefits over lead-based PSCs for nontoxicity and remarkable stability. These two factors are now the primary concerns in the photovoltaic community. The power conversion efficiency (PCE) of PSCs using the lead Pb-free chemical methylammonium bismuth iodide (CH3NH3)3Bi2I9 is severely limited due to the poor quality of the photoactive material. Herein, the photovoltaic performance of the (CH3NH3)3Bi2I9 PSCs was investigated. The objective of this study was to investigate the intrinsic impacts of (CH3NH3)3Bi2I9 perovskite by using SCAPS-1D (Solar Cell Capacitance Simulator) to simulate the PSCs and the adjustment of relevant physical parameters to closely match experimental results. Moreover, the cells were optimized based on (CH3NH3)3Bi2I9 film thickness, total defect density of (CH3NH3)3Bi2I9, optical bandgap, and interfacial defects. By conducting a comprehensive analysis of the current-voltage (J-V) plots and quantum efficiency feature, the best values of perovskite thickness, bandgap, and defect density were determined to be 100 nm, 1.6 eV, and 1014 cm-3, respectively. Furthermore, defects in the interfaces between the electron-transporting layer (ETL)/(CH3NH3)3Bi2I9 and hole transport layer (HTL)/(CH3NH3)3Bi2I9 were considered, and their influence on performance was also investigated. Accordingly, the optimized cell has realized a record PCE of 9.043% and a high quantum efficiency exceeding 60%, which is comparable to those of some Pb-free perovskite analogues. The operational temperature calucations showed that all parameters remain relatively constant with increasing temperature. Therefore, the results imply that the simulated Pb-free PSCs can be stable in a thermal environment. The proposed structural layout and optimization approach can encourage more study and actual applications for Pb-free organometallic perovskite solar cells.

Internal Encapsulation Enables Efficient and Stable Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs) have made significant strides in efficiency, but their long‐term stability remains a challenge. While external encapsulation mitigates extrinsic degradation and lead leakage, it does not fully address performance decline due to ion migration within the perovskite devices. Therefore, an internal encapsulation layer that can selectively transport charge carriers and suppress ion migration across the interface is of great significance for achieving long‐term stability in these devices. Here, polytetrafluoroethylene (PTFE) can serve as an effective internal encapsulation layer between the perovskite film and the electron transport layer in the inverted PSCs is demonstrated. The PTFE layer can selectively transport electrons and suppress ion diffusion, resulting in a higher power conversion efficiency (PCE) of 25.49% compared to 24.74% of the control devices and much better long‐term stability. Even after 1500 h of air exposure, the internal encapsulated perovskite devices can maintain 92.6% of their original PCE, outperforming the control devices at 80.4%. This approach offers a novel solution for addressing ion migration‐induced instability in perovskite devices.

Exploring Sb2S3 as a hole transport layer for GeSe based solar cell: A numerical simulation

Abstract Germanium selenide (GeSe) and antimony sulfide (Sb2S3) both are technological intriguing semiconductor material for green and economical photovoltaic devices. In this study, GeSe and Sb2S3 have been utilized as the absorber layer and hole transport layer, respectively, to constructed a heterojunction thin film solar cell consisting of FTO/TiO2/GeSe/Sb2S3/Metal. The GeSe and Sb2S3 are binary compounds and can adopt the same film deposition method, for instance, thermal evaporation, which is expected to improve process compatibility and to reduce production costs. The TiO2 (electron transport layer) and Sb2S3 can form small spike-like conduction band offset and valence band offset with the GeSe, respectively, which possesses potential to suppress carrier recombination at the heterointerfaces. Subsequently, the effects of main functional layer material parameters, heterointerface characteristics and back contact metal work function on the performance parameters of the proposed solar cell were simulated and analyzed using wxAMPS software. After numerical simulation and optimization, the proposed solar cell can reach an open circuit voltage of 0.872 V, a short circuit current of 40.72 mA·cm-2, a filling factor of 84.16%, and a conversion efficiency of 28.35%. According to the simulation results, it is anticipated that the Sb2S3 can serve as a hole transport layer for GeSe based solar cell and enable device to achieve high efficiency. Simulation analysis also provides some meaningful references for the design and preparation of heterojunction thin film solar cells.

Triple-junction Dion-Jacobson perovskite tandem solar cells: advancing efficiency via interface optimization and broadened light absorption spectrum

Abstract Dion-Jacobson (DJ) perovskites have emerged as game-changers in the world of photovoltaics due to their unique combination of advantages like cost-effective fabrication, tailorable bandgap, and exceptional efficiency. Further, in this study, MXene contacts have been utilized with 2D-perovskites solar cells to leverage the advantages of both, leading to improved stability, superior charge transport, and adjustable energy bandgap without the occurrence of pinhole effects. To further tap into the immense potential of perovskites, this study explores the power of a triple-junction All DJ perovskite tandem solar cell (ADJT-PSC) architecture. This design captures a broader spectrum of sunlight, maximizing energy harvesting and unlocking new possibilities for photovoltaic devices. In this symphony of light and power, 1.5-pentamethylenediamine (PeDA) methylammonium lead iodide (PeDAMAPb2I7) (1.98 eV), PeDAMA5Pb6I19 (1.6 eV), CsLaTa2Se7 (1.1 eV) take as the absorber layers in the top, middle, and bottom subcells, respectively. Moreover, optimizing the thickness of each perovskite layer is crucial for maximizing efficiency. This study conducted a thorough analysis and identified the ideal 350 nm/550 nm/200 nm thicknesses for the top/middle/bottom layers, respectively. Furthermore, the study explored the art of doping variation in the electron and hole transport layers. By meticulously adjusting the doping levels, ADJT-PSC can achieve a maximum efficiency of 35%.

Cross‐Linkable Fullerene Electron Transport Layer with Internal Encapsulation Capability for Efficient and Stable Inverted Perovskite Solar Cells

AbstractA stable and compact fullerene electron transport layer (ETL) is crucial for high‐performance inverted perovskite solar cells (PSCs). However, traditional fullerene‐based ETLs like C60 and PCBM are prone to aggregate under operational conditions, a challenge recently recognized by academic and industrial researchers. Here, we designed and synthesized a novel cross‐linkable fullerene molecule, bis((3‐methyloxetan‐3‐yl)methyl) malonate‐C60 monoadduct (BCM), for use as an ETL in PSCs. Upon a low‐temperature annealing at 100 °C, BCM undergoes in situ cross‐linking to form a robust cross‐linked BCM (CBCM) film, which demonstrates excellent electron mobility and a suitable band structure for efficient PSCs. Our results show that PSCs incorporating CBCM‐based ETL achieve an impressive efficiency of 25.89 % (certified: 25.36 %), significantly surpassing the 23.25 % efficiency of PCBM‐based devices. The intramolecular covalent interactions within CBCM films effectively prevent aggregation and enhance film compactness, creating an internal encapsulation layer that mitigates the decomposition and ion migration of perovskite components. Consequently, CBCM‐based PSCs show exceptional stability, maintaining 97.8 % of their initial efficiency after 1000 hours of maximum power point tracking, compared to only 78.6 % retention in PCBM‐based devices after less than 820 hours.

Thickness and Doping Density Influence of a High-Voltage Inorganic Perovskite Solar Cell: A SCAPS 1-D Simulation Study

Recently, all inorganic perovskite solar cells have triggered great attention thanks to the rising performance during their development in solid state photovoltaics showing enhanced characteristics, such as: good stability, high photoluminescence quantum yield, tunable size, and morphology. In this work, a high open-circuit voltage solar cell based on all-inorganic perovskite through SCAPS simulator program is presented by analysing electron transport layer (ETL), perovskite layer, hole transport layer (HTL) thickness and doping density from a FTO/TiO2/CsPbBr3/Spiro-OMeTAD/Au structure were modified to observe its influence on solar cell performance. Therefore, simulation results show that a thicker ETL hinders carrier transport towards the FTO layer due to larger distance which leads to higher recombination rate, reducing carrier’s lifetime. Albeit high doping density values in ETL enhances the overall solar cell performance. As for the absorber layer, while its thickness increases, carrier collection rate decreases due to recombination impacting Voc, which results from thickness increase. Based on the results, solar cell efficiency improvement is attributed to the built-in electric field as absorber layer doping density increases. While HTL thickness has minimum impact on the solar cell output, doping density enhances device parameters significantly. Summarising the results obtained from thickness and doping density simulations, the optimal solar cell operation was obtained at 10 nm, 600 nm, and 100 nm layer thickness as well as 1020 cm-3, 1016 cm-3, and 1020 cm-3 doping density (TiO2, CsPbBr3 and Spiro-OMeTAD). Results from three different sources, collected from literature, were used to compare, and fitting them along with simulation results.

Efficient and Stable Wide‐Bandgap Methylammonium‐Free Perovskite Solar Cells by Simultaneous Passivation and Cleaning with Diamine

Wide‐bandgap perovskite solar cells (WBG‐PSCs) are pivotal in achieving high‐performance tandem solar cells. However, their power conversion efficiency (PCE) is limited by the losses from the interfacial charge transfer barrier and nonradiative recombination. In this investigation, 1,4‐bis(aminomethyl)benzene (PDMA) is employed as a defect passivator for fabricating methylammonium (MA)‐free perovskite solar cells (PSCs), thus effectively mitigating nonradiative recombination losses of charge carriers. Meanwhile, PDMA molecules chemically rinse the perovskite film to create a grooved surface, leading to the increase of contact area between the perovskite and electron transport layer to further improve the interfacial charge transfer. As a result, the PSCs based on these surface‐passivated and chemically cleaned perovskite films present a champion PCE of 21.23% (Eg = 1.68 eV) compared to the control devices with a PCE of 18.23%, while maintaining over 80% efficiency after 800 h storage in ambient air. This study presents a highly effective approach for one‐step passivation and chemical cleaning of wide‐bandgap perovskite for efficient and stable solar cells, offering valuable insights for future research in this field.

Enhancing the Efficiency and Stability of Inverted Perovskite Solar Cells and Modules through Top Interface Modification with N‐type Semiconductors

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i‐PPVs). Herein, non‐fullerene acceptors (NFAs), known as Y6‐BO and Y7‐BO, were utilized to modify the perovskite/ETL interface in i‐PPVs. Non‐polar solvent‐soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved PCBM ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6‐BO and Y7‐BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i‐PSC) modified with Y7‐BO reaches 25.82%. Moreover, the adoption of non‐polar solvents and the superior semiconductor properties of Y7‐BO molecules also enable perovskite solar modules (i‐PSM) with effective areas of 50 cm2, 400 cm2, and 1160 cm2 to achieve record efficiencies of 23.05%, 22.32%, and 21.1% (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7‐BO maintained 94.4% of the initial efficiency after 1522 hours of maximum power point aging.

Enhancing the Efficiency and Stability of Inverted Perovskite Solar Cells and Modules through Top Interface Modification with N-type Semiconductors.

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i-PPVs). Herein, non-fullerene acceptors (NFAs), known as Y6-BO and Y7-BO, were utilized to modify the perovskite/ETL interface in i-PPVs. Non-polar solvent-soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved PCBM ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6-BO and Y7-BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i-PSC) modified with Y7-BO reaches 25.82%. Moreover, the adoption of non-polar solvents and the superior semiconductor properties of Y7-BO molecules also enable perovskite solar modules (i-PSM) with effective areas of 50 cm2, 400 cm2, and 1160 cm2 to achieve record efficiencies of 23.05%, 22.32%, and 21.1% (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7-BO maintained 94.4% of the initial efficiency after 1522 hours of maximum power point aging.

Tetrabutylammonium Hydroxide-Functionalized Ti3C2Tx MXene for Significantly Improving the Photovoltaic Performance of Perovskite Solar Cells.

An appropriate electron transport layer (ETL) or cathode buffer layer (CBL) is critical for high-performance perovskite solar cells (PVSCs). In this work, tetrabutylammonium hydroxide (TBAOH)-functionalized Ti3C2Tx MXene (TBAOH-Ti3C2Tx) is developed to improve the photovoltaic performance of PVSCs. TBAOH-Ti3C2Tx is synthesized by HF etching and then TBAOH intercalation, and TBAOH can effectively attach to the Ti3C2Tx surface during the intercalation process. In hole transport material (HTM)-free carbon-based PVSCs with the structure of ITO/ETL/MAPbI3/carbon, the SnO2 doped by TBAOH-Ti3C2Tx (SnO2:TBAOH-Ti3C2Tx) as ETL shows decreased WF and increased conductivity and improves the growth of the perovskite film with a larger grain and significantly reduced defects, which synergistically facilitate charge transport and extraction and reduce charge recombination. The HTM-free carbon-based PVSC with SnO2:TBAOH-Ti3C2Tx ETL exhibits a significantly higher PCE of 14.93% with enhanced device stability compared to the control device with pristine SnO2 ETL (11.95%) and also outperforms most of the HTM-free carbon-based PVSCs with MAPbI3 perovskite reported so far. In traditional inverted PVSCs with the structure of ITO/PTAA/MAPbI3/PCBM/CBL/Ag, the TBAOH-Ti3C2Tx is utilized as a CBL to significantly enhance device performance with a high PCE of 21.16%, which is obviously superior than that (16.26%) of the control device without CBL. The impressive results indicate that tetrabutylammonium hydroxide-functionalized Ti3C2Tx MXene possesses great application potential in different functional layers for high-performance PVSCs.

Investigation of internal thermal distribution in inverted perovskite solar cell and improvement of its heat dissipation performance

Abstract COMSOL Multiphysics software was used to construct a numerical opto-electro-thermal coupling model to investigate the mechanisms of internal heat generation, conduction, and dissipation in inverted (p-i-n architecture) perovskite solar cells (PSCs). The research results indicate that Joule heating and Shockley-Read-Hall (SRH) recombination are the primary sources of heat, leading to significant accumulation of heat at the interfaces between the perovskite and the electron transport layer (ETL), as well as between the ETL and the electrode. This concentration of heat not only affects the performance of the device but also poses challenges for overall thermal management. Therefore, we compared four different top electrode materials (Ag, Cu, Al, and reduced graphene oxide) to assess their performance in terms of heat dissipation efficiency. The results showed that reduced graphene oxide (RGO) performed exceptionally well in heat dissipation efficiency, primarily due to its high thermal conductivity, which enables it to effectively reduce heat accumulation at the interfaces, thereby improving performance of PSCs. This finding provides important material selection criteria for optimizing the thermal management of PSCs.

Numerical simulation of electrically pumped active vertical‐cavity surface‐emitting lasers diodes based on metal halide perovskite

AbstractMetal halide perovskites (MHP)‐based electrically pumped vertical‐cavity surface‐emitting lasers (EPVCSEL) are promising candidates in optoelectronics due to low‐carbon footprint solution processing method. However, significant challenges impede MHP‐EPVCSEL manufacturing: (1) Distributed Bragg Reflectors (DBRs) composed of typical electron transport layers (ETLs) and hole transport layers (HTLs) are not conductive enough. (2) Due to large mobility difference of typical ETLs and HTLs, carriers‐unbalanced injection leads to severe performance degradation. Herein, we propose a potential strategy to address such challenges using MAPbCl3 and CsSnCl3 as carrier transport layers with mobility 3 orders larger than typical ETLs and HTLs. Via transfer matrix method calculations, we find that the reflectance of DBRs composed of MAPbCl3 (130.5 nm)/CsSnCl3 (108 nm) is larger than 91% with 10 pairs of DBRs. Furthermore, the proposed EPVCSEL device simulation shows that MHP‐EPVCSEL has the potential to achieve room temperature continuous wave lasing with a threshold current density of ∼69 A cm−2 and output optical power ∼10−4 W. This work can provide a deep insight into the practical realization of MHP‐EPVCSEL.

Compact Layer‐Free Perovskite Solar Cells with Low‐Temperature UVO Photochemical Annealed Mesoporous TiO2 Layers

In recent years, the field of perovskite solar cells (PSCs) has seen rapid development, with most high‐efficiency devices incorporating dense titanium dioxide (TiO2) barrier layers and mesoporous TiO2 layers to enhance selective electron transport. However, the manufacturing process requires high‐temperature sintering steps above 450 °C, leading to significant energy consumption. In addition, this requirement greatly limits the potential applications of PSCs in the field of flexible electronics. This study introduces a new method for preparing dense‐layer‐free mesoporous PSCs using low‐temperature UVO annealing of m‐TiO2. UVO annealing effectively removes residual organic components from m‐TiO2 precursor films, enhances the conductivity and wettability of the films, thereby reducing carrier recombination and improving the performance of PSCs. Research has shown that PSC with a 40 min UVO annealed m‐TiO2 layer exhibits a final photoelectric conversion efficiency of 17.79%, comparable to devices with traditional high‐temperature annealed m‐TiO2 PSCs. In addition, after 7 days at room temperature and ambient humidity, the unpackaged device maintains a maximum conversion efficiency of 84%. These findings indicate that UVO light annealing is a feasible alternative to high‐temperature annealing, providing a simpler, more cost‐effective, and energy‐saving method for the preparation of metal oxide electron transport layer in PSCs.