Increase In Power Conversion Efficiency Research Articles

High Polymer Molecular Weight Yields Solar Cells with Simultaneously Improved Performance and Thermal Stability.

Simple synthetic routes, high active layer thickness tolerance as well as stable organic solar cells are relentlessly pursued as key enabling traits for the upscaling of organic photovoltaics. Here, the potential to address these issues by tuning donor polymer molecular weight is investigated. Specifically, the focus is on PTQ10, a polymer with low synthetic complexity, with number average molecular weights of 2.4, 6.2, 16.8, 52.9, and 54.4kDa, in combination with three different non-fullerene acceptors, namely Y6, Y12, and IDIC. Molecular weight, indeed, unlocks a threefold increase in power conversion efficiency for these blends. Importantly, efficiencies above 10% for blade coated devices with thicknesses between 200 and 350nm for blends incorporating high molecular weight donor are shown. Spectroscopic, GIWAXS and charge carrier mobility data suggest that the strong photocurrent improvement with molecular weight is related to both, improved electronic transport and polymer contribution to exciton generation. Moreover, it is demonstrated that solar cells based on high molecular weight PTQ10 are more thermally stable due to a higher glass transition temperature, thus also improving device stability.

All‐Inorganic Perovskite Solar Cells: Modification Strategies and Challenges

Cesium‐based all‐inorganic wide‐bandgap perovskite solar cells (AIWPSCs) have been demonstrated with exceptional optoelectronic properties such as intrinsic optical wide‐bandgap and high thermal stability, which make them suitable candidates for the front sub‐cells of tandem solar cells (TSCs). Passivation of perovskite surface and interface is a matter of common interest in this community since all‐inorganic perovskites always suffer from non‐ideal crystallization such as phase impurity, high defect density, and non‐uniform morphology. Despite these shortcomings, numerous efforts have been devoted in recent years to pursuing high‐performance AIWPSCs, which exhibit an abruptly increased power conversion efficiency (PCE) from 2.9% to over 21.0%. In view of not having a thorough summary about the advancements on AIWPSCs, herein, a comprehensive review is given to highlight the recent device performance progress of AIWPSC, particularly focusing on the strategies to passivate the defects of all‐inorganic perovskite, namely, additive engineering, solvent engineering, interface modification, and the exploration of new charge transport materials (CTMs) for improving the phase stability and PCE of AIWPSCs. Finally, a conclusive outlook on AIWPSCs will be given to provide our perspectives aiming to inspire the further development of AIWPSCs.

Theoretical analysis of doping of perovskite light-absorbing layer for highly efficient perovskite solar cells

The physical properties of perovskites—the central components of perovskite solar cells (PSCs)—are crucial for photovoltaic (PV) performance. Suitable doping of perovskites can improve the electric-field distribution within them, thus enhancing their PV performance. In this study, the effects of the three doping strategies on PV performance of MAPbI3 based PSCs were explored. First, uniform acceptor doping of perovskite was performed. With increasing uniform acceptor doping concentration (NA), the open-circuit voltage (VOC) gradually increased, but the short-circuit current density (JSC) decreased. As the decline in JSC limited further PCE increase, non-uniform acceptor doping of perovskite was performed, which increased the width of the space-charge region near the MAPbI3/SnO2 interface, promoting the flow of holes from MAPbI3 to the carbon electrode. The JSC increased from 19.05 to 22.30 mA cm−2, and the power conversion efficiency (PCE) increased from 19.74 % to 22.72 % when the doping concentration curve for non-uniform acceptor doping was a line passing through 3 × 1018 and 3 × 1014. In order to further enhance the PCE, simultaneous non-uniform acceptor doping and uniform donor doping of perovskite was adopted, which further improved the JSC and fill factor (FF), and the PCE increased from 22.72 % to 23.92 % when the uniform donor doping concentration was 1 × 1018 cm−3. This work provides a strategy of doping of perovskite for highly efficient PSCs.

Leveraging Dion–Jacobson Interface Hierarchies for Defect Alleviation in High-Efficiency and Durable Perovskite Solar Cells

The noteworthy stability of Dion–Jacobson (DJ) phase two-dimensional perovskites marks them as potential contenders for use in optoelectronic applications. Nonetheless, their proliferation is considerably stymied by the constrained charge transport properties inherent to them. This bottleneck is adeptly navigated by deploying 2D-DJ perovskite top layers, seamlessly integrated on 3D perovskite films. We unveil a novel organic cation salt, 4-(Aminomethyl)piperidine (4AMP), as a potent facilitator for treating perovskite photovoltaic films. By employing the annealing technique, we facilitated the in situ creation of a hybrid 2D/3D architecture. Contrasted with conventional 3D architectures, the delineated perovskite heterojunctions with a 2D/3D structure exhibit superior enhanced charge separation, and mitigate photovoltaic losses by proficiently passivating intrinsic defects. The size-graded perovskite 2D/3D structure engineered herein significantly elevates the charge transfer performance, concurrently attenuating the excess lead iodide induced by bulk defects. This precise method resulted in a significant increase in Power Conversion Efficiency, reaching 23.08%, along with an open-circuit voltage (Voc) of 1.17 V. Remarkably, the unpackaged modified device robustly retains 92% of its initial PCE post a 3000 h sojourn under ambient conditions. This discourse propounds a novel paradigm for constructing stable planar PSC 2D/3D heterojunctions, thereby enriching the blueprint for advanced perovskite-based photovoltaic systems.

Unlocking the plasma advantage in elevating the performance of silicon nanowires/ poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) hybrid solar cell

Silicon Nanowires (SiNWs) can be easily synthesized by following the two-step electroless metal-assisted chemical etching method. These SiNWs are well known for their low reflectivity due to their excellent light-harvesting characteristics. In this paper, we demonstrated the effect of plasma treatment time on the performance of SiNWs solar cells. The 1 min plasma-treated SiNWs/Poly 3,4-[ethylene dioxy thiophene:Polystyrene sulfonate] (PEDOT׃PSS) solar cell showed increased power conversion efficiency than the untreated SiNWs/PEDOT׃PSS solar cell. The photo Current density-Voltage (J-V) analysis showed that the open circuit voltage (VOC) of the plasma treated solar cell for 1 min is higher (270 mV) than that of the untreated solar cell (120 mV). The increase in the value of VOC comes from different factors׃ one is due to the formation of a good interface between the SiNWs and PEDOT׃PSS layer; other is the reduction of defect densities in SiNWs/PEDOT׃PSS heterojunction, consequently the reduction in the recombination processes. Hence from this research, we found that by controlling the plasma treatment on SiNWs, it can improve the SiNWs properties which can further improve the efficiency of the solar cell.

Bandgap reduction and efficiency enhancement in Cs2AgBiBr6 double perovskite solar cells through gallium substitution.

Lead-free halide double perovskite (LFHDP) Cs2AgBiBr6 has emerged as a promising alternative to traditional lead-based perovskites (LBPs), offering notable advantages in terms of chemical stability and non-toxicity. However, the efficiency of Cs2AgBiBr6 solar cells faces challenges due to their wide bandgap (Eg). As a viable strategy to settle this problem, we consider optimization of the optical and photovoltaic properties of Cs2AgBiBr6 by Gallium (Ga) substitution. The synthesized Cs2Ag0.95Ga0.05BiBr6 is rigorously characterized by means of X-ray diffraction (XRD), UV-vis spectroscopy, and solar simulator measurements. XRD analysis reveals shifts in peak positions, indicating changes in the crystal lattice due to Ga substitution. The optical analysis demonstrates a reduction in the Eg, leading to improvement of the light absorption within the visible spectrum. Importantly, the Cs2Ag0.95Ga0.05BiBr6 solar cell exhibits enhanced performance, as evidenced by higher values of open circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF), which are 0.94 V, 6.01 mA cm-2, and 0.80, respectively: this results in an increased power conversion efficiency (PCE) from 3.51% to 4.52%. This research not only helps to overcome film formation challenges, but also enables stable Cs2Ag0.95Ga0.05BiBr6 to be established as a high-performance material for photovoltaic applications. Overall, our development contributes to the advancement of environmentally friendly solar technologies.

Perovskite Solar Cells With Modified Carbon Electrode and CuSCN Interlayer Processed Under Ambient Conditions

Carbon‐based perovskite solar cells (PSCs) have the advantages of a long lifetime and are compatible with highly scalable manufacturing processes. The use of carbon electrodes and the absence of a hole selective layer (HSL) promote a simplified fabrication process. However, the efficiency of HSL‐free carbon‐based PSCs is inferior to PSCs that utilize metal electrodes and HSL due to poor hole extraction at the perovskite/carbon interface. To overcome those issues, researchers added an interlayer on the perovskite/carbon interface or incorporated additive material into the carbon layer. However, there is limited research on utilizing both strategies to improve carbon‐based PSC performance. Here, we use CuSCN as an interlayer between the perovskite/carbon interface and a carbon additive in carbon‐based PSCs. By utilizing both strategies, the charge transfer of carbon‐based PSC was significantly improved compared to carbon‐based PSC utilizing only one improvement strategy. Confirmed by photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) characterizations, the CuSCN interlayer and CuSCN‐incorporated carbon electrode enable more efficient hole transfer, resulting in an increased power conversion efficiency from 0.58% to 5.06%. The proposed PSC structure shows promising results for further improving carbon‐based PSC performance.

Using Ag nanoparticles in the electron transport layer of perovskite solar cells to improve efficiency

The incorporation of metal nanoparticles within various types of photovoltaic technologies has been shown to increase the performance of organic solar cells, dye sensitized solar cells, and more recently perovskite solar cells. Using this type of nanostructured composite transport layer could help improve the efficiency and stability of perovskite solar cells whilst avoiding the use of dopants that can damage the perovskite layer. In this work, Ag nanoparticles are synthesized and used to form a SnO2:Ag nanoparticle composite transport layer for the first time. On its own, SnO2 is in one of the most efficient transport layers for perovskite solar cells. Upon inclusion of the Ag nanoparticles the recombination rate is increased (detrimental for device performance) as shown by impedance spectroscopy, and the charge carrier transfer and extraction is enhanced (beneficial for device performance) as shown by photoluminescence measurements. In order to balance these opposing factors, the nanoparticle concentration was optimized at an intermediate concentration with a corresponding power conversion efficiency increase from 13.4 ± 0.7 % for reference solar cells without nanoparticles to 14.3 ± 0.3 % for those with nanoparticles. These devices are one of the first examples of, and exhibit the highest reported efficiency for, perovskite solar cells fabricated completely in air with nanocomposite oxide layers. The protocol developed and reported here to improve the nanocomposite transport layer has general applicability in other fields, including LEDs, FETs, and electronic devices where transparency and conductivity are also required.

Enhancing the inherent stability of perovskite solar cells through chalcogenide-halide combinations

Perovskite solar cells have attracted much attention due to their rapidly increasing power conversion efficiency, however, their poor inherent long-term stability limits their commercialization.

Efficient and Stable Perovskite/Silicon Tandem Solar Cells Modulated with Triple‐Functional Passivator

AbstractPerovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2‐fluoroisonicotinic acid (2‐FNA) additive that possesses fluorine (‐F), carboxylic acid (‐COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2‐FNA can efficiently reduce the defects and suppress non‐radiative recombination of perovskite layers by bonding with the uncoordinated Pb2+ ions, formamidinium (FA+), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2‐FNA aids in the formation of better interfacial contact between the perovskite and C60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs.

Interfacial bidirectional binding for improving photovoltaic performance of perovskite solar cells

SnO2 as an electron transport layer (ETL) has recently been used for perovskite solar cells (PSCs) due to high transmittance and electron mobility. However, the mismatched band energy alignment of ETL and perovskite layer result in serious nonradiative recombination limiting the improvement of PSCs performance. Here, 2-(Diphenylphosphino)ethanaminium tetrafluoroborate (DPEBF4) as buried interface was introduced between ETL and perovskite. The [BF4]− anion in DPEBF4 can interact with SnO2 to reduce the surface defect of SnO2. While [DPE]+ cation is more inclined to interact with Pb2+ and I−, the terminal strong interaction will promote crystallization of perovskite film quality and passivate buried surface defects. As a result, device performance was significantly improved by introducing DPEBF4 layer, the power conversion efficiency (PCE) increase from 20.50 % for control devices to 23.84 %. The work provides an interfacial double-tonic strategy for ETL and perovskite crystals to achieve high-performance perovskite photovoltaic devices.

Understanding the Heterointerfaces in Perovskite Solar Cells via Hole Selective Layer Surface Functionalization.

Interfaces in perovskite solar cells (PSCs) play a pivotal role in determining device performance by influencing charge transport and recombination. Understanding the physical processes at these interfaces is essential for achieving high-power conversion efficiency in PSCs. Particularly, the interfaces involving oxide-based transport layers are susceptible to defects like dangling bonds, excess oxygen, or oxygen deficiency. To address this issue, the surface of NiOx is passivated using octadecylphosphonic acid (ODPA), resulting in improved charge transport across the perovskite hole transport layer (HTL) interface. This surface treatment has led to the development of hysteresis-free devices with an impressive ≈13% increase in power conversion efficiency. Computational studies have explored the halide perovskite architecture of ODPA-treated HTL/Perovskite, aiming to unlock superior photovoltaic performance. The ODPA surface functionalization has demonstrated enhanced device performance, characterized by superior charge exchange capacity. Moreover, higher band-to-band recombination in photoluminescence and electroluminescence indicates presence of lower mid-gap energy states, thereby increasing the effective photogenerated carrier density. These findings are expected to promote the utilization of various phosphonic acid-based self-assembly monolayers for surface passivation of oxide-based transport layers in perovskite solar cells. Ultimately, this research contributes to the realization of efficient halide PSCs by harnessing the favorable architecture of NiOx interfaces.

Data-driven design for enhanced efficiency of Sn-based perovskite solar cells using machine learning

In this study, a novel three-step learning-based machine learning (ML) methodology is developed utilizing 26 000 experimental records from The Perovskite Database Project. A comprehensive set of 29 features encompassing both categorical and numerical data was utilized to train various ML models for various solar cell performance metrics, including open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE). The model accuracy was assessed using four key metrics: mean absolute error, mean square error, root mean square error, and R2 score. Among the constructed models, random forest (RF) emerged as the standout performer, boasting an R2 score of 0.70 for PCE. This RF model was then used for prediction on the large, optimized design pool of Sn-based perovskite data with intent to probe a viable non-toxic substitute to the standard Pb-based absorber. A three-step algorithm was tailored, which led to the discovery of a new set of feature combinations, showcasing a PCE improvement over the existing peak performance of Sn-based devices. The key aspects identified were device architecture, dimensionality, and deposition procedures for essential layers, including the electron transport layer, the hole transport layer, the perovskite absorber layer, and the back-contact. Through consideration of these features, an impressive increase in PCE was achieved. There was a 28.35% increase in PCE from 12.24% to 15.71% for architecture optimization and a 24.6% increase in PCE from 12.24% to 15.25% for deposition method optimization. This study additionally addresses the effective implementation of target encoding applied to a diverse set of categorical feature labels. The data-driven methodology proposed in this study allows scientists to efficiently identify an optimal architecture and deposition parameters for non-toxic Sn-based perovskite materials with a much higher anticipated device PCE compared to traditional trial-and-error analyses. Further exploration and exploitation of the current investigation is expected to lead to successful and sustainable development of highly efficient Sn-based perovskite solar cells.

Revealing Design Rules for Improving The Photostability of Non‐Fullerene Acceptors from Molecular to Aggregation Level

AbstractWith the rapid increase in power conversion efficiency of organic photovoltaics due to the development of non‐fullerene acceptors (NFAs), prolonging the operational lifetime of devices becomes one of the critical prerequisites for commercial application. In this work, the degradation pathways of a wide range of state‐of‐the‐art NFA molecules via multiple spectroscopic techniques combined with density functional theory and molecular dynamics simulation are revealed. The structural confinement and molecular ordering are responsible for molecular conformational stability under illumination. More importantly, a very general trend is revealed that the origin of increased nonradiative decay under illumination is predominately in the aggregated states with strong intermolecular interactions while the intramolecular exciton dynamics are stable. The increased nonradiative decay correlates with reduced exciton diffusion length. This work provides vital information toward the design of intrinsically photo‐stable NFAs at the molecular level and the importance of aggregation control toward long‐term stable organic solar cells.

Dye-sensitized solar cells containing photoelectrodes with TiO2 grids

A 90-nm-thick TiO2 grid is created through photolithography, sputtering and lift-off process in this study. A nanoporous film is deposited on the TiO2 grid. The grid induces a protrusive structure in the nanoporous film. Experimental results demonstrate that introducing the TiO2 grid into a dye-sensitized solar cell increases its power conversion efficiency by 25% compared to a dye-sensitized solar cell lacking a TiO2 grid. Consequently, the TiO2 grid proves beneficial in augmenting the power conversion efficiency of the dye-sensitized solar cell. The increased power conversion efficiency of the dye-sensitized solar cell containing the TiO2 grid is attributed to the large surface area and directional electron transport channels of the protrusive structure. The TiO2 grid offers advantages such as simple fabrication, cost-effective production and improved power conversion efficiency.

Improved performance of double Cs2AgBiBr6 perovskite solar cells by engineering passivation defects with Co2+ additives

Cs2AgBiBr6, a double perovskite structure, offers potential as a stable and non-toxic alternative to organic lead perovskites. However, challenges such as poor film quality and a wide indirect band gap have limited its applications. In this study, we introduced Co2+ cations into the precursor solution to slow down Cs2AgBiBr6 film crystallization kinetics. This intervention led to improved film quality, larger grain sizes, reduced defect densities, band gap modulation, and increased solar cell efficiency. Additionally, Co2+ B-site substitution effectively reduced bromine vacancies in the pristine perovskite, mitigating carrier defect recombination. Co2+ also lowered the band gap of Cs2AgBiBr6 and adjusted energy level arrangements, facilitating carrier transport, enhancing electron-hole extraction, and improving conductivity. We investigated the optimal Co2+ addition ratio and elucidated the enhancement mechanisms. The introduction of Co2+ increased power conversion efficiency from 2.11 % to 3.50 % and short-circuit current density from 3.88 to 4.88 mA/cm2. This study offers a straightforward method to enhance Cs2AgBiBr6-based solar cells.

Optical–electrical simulation and optimization of an efficient lead-free 2T all perovskite tandem solar cell

The characteristics of a lead-free all perovskite tandem solar cell (P-TSC) are studied in this study. All P-TSCs were developed with the goal of breaking through the theoretical power conversion efficiency (PCE) limit for single-junction (SJ) perovskite solar cells (PSCs) established by Shockley and Queisser. Solving the toxicity problem in lead-containing sub-cells is essential for the continued growth of all P-TSCs. Here, we first present a coupled three-dimensional (3D) optical–electrical simulation of two lead-free SJ MAGeI3(Eg=1.9eV) and MASnI3(Eg=1.3eV) PSCs. The results showed that the PCE of the SJ-wide bandgap (WBG) and SJ-narrow bandgap (NBG) PSCs is 19.59% and 15.57%, respectively. Next, a two-terminal (2T) eco-friendly all P-TSC with combines these two solar cells has been designed, where the MAGeI3-PSC serves as the top sub-cell and the MASnI3-PSC serves as the bottom sub-cell. By establishing the current matching condition between two sub-cells in the 2T structure, the matched short-circuit current density (Jsc) and PCE are obtained 12.30mA/cm2 and 28.46%, respectively. Herein, a 299 nm-thick NBG-absorber layer and a 200 nm-thick WBG-absorber layer are required. In order to increase the matched Jsc and PCE and decrease the required NBG-absorber layer thickness, the parasitic absorption and reflection losses are minimized by selecting the best materials for the transparent conductive oxide (TCO) front contact and interconnecting (IC) layers, as well as the addition of an anti-reflection (AR) layer at the air/device interface as light management strategies. The results indicate that, under the current matching condition, improving the structure would lead to in a 76 nm reduction in the NBG-absorber layer’s required thickness and a 16.44% increase in PCE. Finally, we suggested the optimized 2T non-Pb all P-TSC with a high PCE of 33.14% that is environmentally safe.

Improvement of Performance of Cu2ZnSn(S, Se)4 Solar Cells by Low‐Temperature Annealing of B‐Doped CdS

It is known that high carrier recombination at the p–n junction interface and low carrier separation ability (CSA) are two main problems resulting in low power conversion efficiency (PCE) of the Cu2ZnSn(S,Se)4 (CZTSSe) solar cell. To resolve these problems, one CZTSSe solar cell is prepared through substituting B‐doped CdS for CdS in a solar cell with the conventional structure of Ag/ITO/ZnO/CdS/CZTSSe/Mo/SLG and annealing B‐doped CdS/CZTSSe/Mo/SLG prior to deposition of ZnO, ITO, and Ag electrode. By optimizing the B doping content in the CdS and annealing temperature and time of the B‐doped CdS/CZTSSe, lattice mismatch between CdS and CZTSSe is decreased and width of depletion region is increased, leading to reduction in interfacial recombination, enhancement in CSA and intensity of incident light passing through the B‐doped CdS, and so increase in PCE from 7.89% of CZTSSe solar cell using CdS as buffer layer to 10.62%. A mechanism of the increment of the PCE induced by B doping and annealing is suggested. This work proposes a method of increasing PCE of CZTSSe solar cell and advances a deeper understanding of the mechanisms behind various parameters in CZTSSe solar cells through theoretical analysis and calculations.

Cu(In,Ga)Se_2-based solar cells for space applications: proton irradiation and annealing recovery

In this work, we present an experimental study of a Cu(In,Ga)Se_2 (CIGS)-based solar cell (SC), irradiated with protons of energy 80 and 180 keV and with fluences of 10^{12}, 10^{13}, and 10^{14} cm^{-2}, as well as a strategy to recover the induced damage. The possible modifications of the structural, electrical, and optical properties, induced by the proton irradiation, were investigated. Although the irradiation did not promote any major modification in the crystalline structure, it did induce the creation of defects responsible for changes in the electronic structure which caused a partial PL quenching and significant changes in the PL spectral shape, as well as a reduction of the power conversion efficiency and open-circuit voltage of up to 30% as revealed by J–V measurements. The photoluminescence results showed a broadening, redshift and decrease in the signal-to-noise ratio. The recovery of damage induced by irradiation in several SCs was tested through annealing steps performed at different temperatures and time intervals. It was found that the best recovery strategy for the investigated irradiation parameters was carrying out several isothermal annealing at 200 °C for 30 min. This strategy is compatible with the intermittent variation of the temperature in space and allowed to recover a power conversion efficiency comparable to that of the as grown cell. In particular, it must be highlighted that keeping the SC at room temperature in ambient atmosphere and in the dark, did not promote significant recovery in contradiction with some previous reports. This recovery methodology was applied in parallel for non-irradiated SCs and no increase in power conversion efficiency was found, but rather a slight decrease. The dominant radiative recombination channel was, apparently, unchanged with the irradiation and the subsequent recovery process. Nonetheless, changes in the concentration of defects of different types cannot be excluded, which is in line with a significant influence of fluctuating potentials in both as grown and after recovery stages of the solar cell. This work constitutes a first systematic study that simultaneously encompasses the influence of proton irradiation on the optical and electrical properties of CIGS SCs and a damage recovery methodology with a high potential to be explored in space applications. Additionally, it contributes to reinforcing the high potential of CIGS technology in the context of creating constellations of small satellites that are being developed by different entities, particularly private ones.

Understanding the Methylammonium Chloride‐Assisted Crystallization for Improved Performance of Lead‐Free Tin Perovskite Solar Cells

In the quest for perovskite materials with reduced toxicity, Sn perovskites are emerging. However, they suffer from material instability and rapid crystallization, leading to high defect densities in the films. In this work, the methylammonium chloride (MACl)‐assisted crystallization as a route to improve stability and optoelectronic quality of quasi 2D/3D PEA0.08FA0.92SnI3 perovskite is demonstrated. For an optimal additive amount (10 mol%), a 37% increase in power conversion efficiency is found. Notably, MACl enhances the films' stability, evidenced by temporal PL tracking. Understanding the effect of MACl addition in this system is interesting for the pursuit of efficient and stable tin‐based devices. The investigations show that MACl addition causes a shift in the optical bandgap and improves morphology, indicating effects in the bulk crystal structure. X‐ray photoelectron spectroscopy confirms the presence of Cl on the surface, but no indication of MA+ is found. Intriguingly, UV photoelectron spectroscopy shows pronounced changes in the density of states. For the first time, it is shown that MACl promotes the formation of a two‐dimensional layer via the surface accumulation of PEA+. The MACl additive lowers the absorber's ionization energy, possibly facilitating hole extraction. Overall, this work highlights a facile route to control the crystallization of Sn perovskites.