Improved Power Conversion Efficiency Research Articles

Multifaceted anchoring ligands for uniform orientation and enhanced cubic-phase stability of perovskite quantum dots

All-inorganic CsPbI3 perovskite quantum dots (PQDs) hold significant potential for next-generation photovoltaics due to their unique optoelectronic properties, and the surface-bound ligand playing a key role in the stability and functionality of CsPbI3 PQDs. Initially used long-chain ligands in PQDs synthesis stabilize the black phase but hinder charge transport when employed to solar cells, necessitating their replacement with shorter ones. However, this leads to the formation of surface defects and loss of tensile strain, resulting in the transition to the undesired orthorhombic phase (δ-phase) and compromising PQD solar cell performance. Therefore, developing a ligand exchange process that achieves the optimal balance between conductivity and stability in PQD solid films continues to be a significant challenge. To address these issues, we developed an efficient ligand-exchange process utilizing a multifaceted anchoring ligand, 2-thiophenemethylammonium iodide (ThMAI). The larger ionic size of ThMA+ compared to Cs+ facilitates the restoration of surface tensile strain in PQDs, while its thiophene and ammonium groups enable effective passivation of surface defects. Owing to these advantages, ThMAI-treated CsPbI3 PQD thin films exhibit improved carrier lifetime, uniform PQD orientation, and increased ambient stability. As a result, the ThMAI-treated CsPbI3 PQD solar cells demonstrate an improved power conversion efficiency (PCE) of 15.3 % and an enhanced device stability.

Room-Temperature Ripening Enabled by Hygroscopic Salts for Hole-conductor-free Printable Perovskite Solar Cells with Efficiency Over 20.

Solution-processed perovskite films generally possess small grain sizes and high density of grain boundaries, which intensify non-radiative recombination of carriers and limits the power conversion efficiency (PCE) of solar cells. In this study, we report the room-temperature ripening enabled by the synergy of hygroscopic salts and moisture in air for efficient hole-conductor-free printable mesoscopic perovskite solar cells (p-MPSCs). Treating perovskite films with proper hygroscopic salts in damp air induces obvious secondary recrystallization, which coarsens the grains size from hundreds of nanometers to several micrometers. It's proposed that the hygroscopic salt at grain boundaries could absorb moisture and form a complex which could not only serve as mass transfer channel but also assist in the dissolution of perovskite grains. This activates mass transfer between small grains and large grains since they possess different solubilities, and thus ripens the perovskite film. Consequently, p-MPSCs treated with the hygroscopic salt of NH4SCN show an improved power conversion efficiency of 20.13% from 17.94%, and maintain >98% of the initial efficiency under maximum power point tracking at 55±5°C for 350 hours.

Achieving High Efficiency and Stability in Organic Photovoltaics with a Nanometer-Scale Twin p-i-n Structured Active Layer.

In pursuing high stability and power conversion efficiency for organic photovoltaics (OPVs), a sequential deposition (SD) approach to fabricate active layers with p-i-n structures (where p, i, and n represent the electron donor, mixed donor:acceptor, and electron acceptor regions, respectively, distinctively different from the bulk heterojunction (BHJ) structure) has emerged. Here, we present a novel approach that by incorporating two polymer donors, PBDBT-DTBT and PTQ-2F, and one small-molecule acceptor, BTP-3-EH-4Cl, into the active layer with sequential deposition, we formed a device with nanometer-scale twin p-i-n structured active layer. The twin p-i-n PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl device involved first depositing a PBDBT-DTBT:PTQ-2F blend under layer and then a BTP-3-EH-4Cl top layer and exhibited an improved power conversion efficiency (PCE) value of 18.6%, as compared to the 16.4% for the control BHJ PBDBT-DTBT:PTQ-2F:BTP-3-EH-4Cl device or 16.6% for the single p-i-n PBDBT-DTBT/BTP-3-EH-4Cl device. The PCE enhancement resulted mainly from the twin p-i-n active layer's multiple nanoscale charge carrier pathways that contributed to an improved fill factor and faster photocurrent generation based on transient absorption studies. The PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl film possessed a vertical twin p-i-n morphology that was revealed through secondary ion mass spectrometry and synchrotron grazing-incidence small-angle X-ray scattering analyses. The thermal stability (T80) at 85 °C of the twin p-i-n PBDBT-DTBT:PTQ-2F/BTP-3-EH-4Cl device surpassed that of the single p-i-n PBDBT-DTBT/BTP-3-EH-4Cl devices (906 vs 196 h). This approach of providing a twin p-i-n structure in the active layer can lead to substantial enhancements in both the PCE and stability of organic photovoltaics, laying a solid foundation for future commercialization of the organic photovoltaics technology.

Comprehensive device modeling and a performance analysis of perovskite-silicon tandem solar cells through light management

Currently, researchers are paying much attention to perovskite-silicon tandem solar cells due to their great potential to surpass the Shockley–Queisser limit of single silicon solar cells. In order to improve the performance of perovskite-silicon tandem solar cells, various techniques have been employed, including selecting textured structures or optimizing the film thickness in the top perovskite cells. However, despite these efforts, significant losses due to surface reflection and unbalanced light absorption still exist, and the accurate predictions combining both optical and electric calculations towards obtaining higher power conversion efficiency (PCE) are still lacking. In this study, we integrated optical and electrical numerical simulations to precisely investigate the effectiveness of using a pyramidal perovskite (MAPbI3) nanostructured film as an example in perovskite-silicon tandem solar cells to reduce the reflective losses and balance the current densities. Through our calculations, the PCE of tandem solar cells can be improved from 23.1% (the planar structures without texturing) to 29.3% in the best-performing textured tandem devices (with a period of 300 nm and peak-to-valley height of 300 nm) under the consistently calculated absorbed and EQE spectrum. Direct comparisons between calculated results and experimental data could also reveal the influence ascribed to a detailed factor that hinders the PCE improvement. These findings offer valuable theoretical insights for the advancement and optimization of perovskite-silicon tandem solar cells.

Molecular Design and High‐Throughput Virtual Screening of Electron Donor and Non‐fullerene Acceptors for Organic Solar Cells

The complicated trilateral relationships among molecular structures, properties, and photovoltaic performances of electron donor and acceptor materials hinder the rapid improvement of power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, the database of 310 donor and non‐fullerene acceptor pairs is constructed and 39 molecular structure descriptors are selected. Four kinds of machine learning (ML) algorithms random forest (RF), extra trees regression, gradient boosting regression trees, and adaptive boosting are applied to predict photovoltaic parameters. The coefficient of determination, Pearson correlation coefficient, mean absolute error, and root mean square error are adopted to evaluate ML performance. The results show that the RF model exhibits the best prediction accuracy. The Gini important analysis suggests the fused ring and aromatic heterocycles are critical fragments in determining PCE. The molecular unit sets are constructed by cutting each donor and acceptor molecules in database. The 31 752 D‐π‐A‐π type donor molecules and 5 455 164 A‐π‐D‐π‐A type acceptor molecules are designed by recombination of molecular units, and 173 212 367 328 donor–acceptor pairs are generated by combining the newly designed donor and acceptor molecules. Based on the predicted PCE using the trained RF model, 42 donor–acceptor pairs exhibit the predicted PCE > 16%, in which the highest PCE is 16.24%.

Over 500°C stable transparent conductive oxide for optoelectronics

AbstractHigh‐temperature stable transparent conductive oxides (TCOs) are highly desirable in optoelectronics but are rarely achieved due to the defect generation that is inevitable during high‐temperature air annealing. This work reports unprecedented stability in aluminum and fluorine co‐doped ZnO (AFZO) films prepared by pulse laser deposition. The AFZO can retain a mobility of 60 cm2 V−1 s−1, an electron concentration of 4.5 × 1020 cm−3, and a visible transmittance of 91% after air‐annealing at 600°C. Comprehensive defect characterization and first principles calculations have revealed that the offset of substitutional aluminum by zinc vacancy is responsible for the instability observed in aluminum‐doped ZnO, and the pairing between fluorine substitution and zinc vacancy ensures the high‐temperature stability of AFZO. The utility of AFZO in enabling the epitaxial growth of (AlxGa1−x)2O3 film within a high‐temperature, oxygen‐rich environment is demonstrated, facilitating the development of a self‐powered solar‐blind ultraviolet Schottky photodiode. Furthermore, the high‐mobility AFZO transparent electrode enables perovskite solar cells to achieve improved power conversion efficiency by balancing the electron concentration‐dependent conductivity and transmittance. These findings settle the long‐standing controversy surrounding the instability in TCOs and open up exciting prospects for the advancement of optoelectronics.image

Buried interface molecular hybrid for inverted perovskite solar cells.

Perovskite solar cells with an inverted architecture provide a key pathway for commercializing this emerging photovoltaic technology because of the better power conversion efficiency and operational stability compared with the normal device structure. Specifically, power conversion efficiencies of the inverted perovskite solar cells have exceeded 25% owing to the development of improved self-assembled molecules1-5 and passivation strategies6-8. However, poor wettability and agglomeration of self-assembled molecules9-12 cause interfacial losses, impeding further improvement in thepower conversion efficiency and stability. Here we report a molecular hybrid at the buried interface in inverted perovskite solar cells that co-assembled the popular self-assembled molecule [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) with the multiple aromatic carboxylic acid 4,4',4″-nitrilotribenzoic acid (NA) to improve the heterojunction interface. The molecular hybrid of Me-4PACz with NA could substantially improve the interfacial characteristics. The resulting inverted perovskite solar cells demonstrated a record certified steady-state efficiency of 26.54%. Crucially, this strategy aligns seamlessly with large-scale manufacturing, achieving one of the highest certified power conversion efficiencies for inverted mini-modules at 22.74% (aperture area 11.1 cm2). Our device also maintained 96.1% of its initial power conversion efficiency after more than 2,400 h of 1-sun operation in ambient air.

Efficiency enhancement above 31 % of Sb2Se3 solar cells with optimizing various BSF layer

Recent advancements in solar technology have increased the acceptance of antimony selenide (Sb2Se3) due to its advantageous properties. This study aims to enhance the performance of the Sb2Se3 structure by using tungsten disulfide (WS2) as the window layer and copper zinc tin selenide (CZTSe) as the back surface field (BSF) layer, utilizing SCAPS-1D (solar cell and capacitance simulator). An initial investigation of seven potential BSF layers identified CZTSe as the best choice for improving power conversion efficiency (PCE). By carefully simulating various parameters, including the thicknesses of the absorber and window layers, donor and acceptor densities, defect density, shunt resistance, and series resistance, significant performance improvements were achieved. Without the BSF layer, the cell showed a PCE of 28.20 % along with specific values for short circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF). The addition of the BSF layer increased the PCE to 31.52 %, along with enhancements in JSC, VOC, and FF. These results highlight the potential of this approach for developing high-performance Sb2Se3 based solar cells, surpassing conventional designs.

Evaluating Fluorinated-Aniline Units with Functionalized Spiro[Fluorene-9,9'-Xanthene] as Hole-Transporting Materials in Perovskite Solar Cells and Light-Emitting Diodes.

In the field of perovskite optoelectronics, developing hole-transporting materials (HTMs) on the spiro[fluorene-9,9'-xanthene] (SFX) platform is one of the current research focuses. The SFX inherits the merits of spirobifluorene in terms of the configuration and property, but it is more easily derivatized and regulated by virtue of its binary structure. In this work, we design and synthesize four isomeric SFX-based HTMs, namely m-SFX-mF, p-SFX-mF, m-SFX-oF, and p-SFX-oF, through varying the positions of fluorination on the peripheral aniline units and their substitutions on the SFX core, and the optoelectronic performance of the resulting HTMs is evaluated in both perovskite solar cells (PSCs) and light-emitting diodes (PeLEDs) by the vacuum thermal evaporating hole-transporting layers (HTLs). The HTM p-SFX-oF exhibits an improved power conversion efficiency of 15.21% in an inverted PSC using CH3NH3PbI3 as an absorber, benefiting from the deep HOMO level and good HTL/perovskite interface contact. Meanwhile, the HTM m-SFX-mF provides a maximum external quantum efficiency of 3.15% in CsPb(Br/Cl)3-based PeLEDs, which is attributed to its perched HOMO level and shrunken band-gap for facilitating charge carrier injection and then exciton combination. Through elucidating the synergistic position effect of fluorination on aniline units and their substitutions on the SFX core, this work lays the foundation for developing low-cost and efficient HTMs in the future.

2D Dion Jacobson/3D perovskite heterojunction solar cells without hole transport layer: Further optimize the performance by SCAPS-1D

The global energy demand is steadily increasing, prompting a widespread focus on renewable energy sources such as solar, wind, hydro, and biomass. Perovskite solar cells (PSCs) have gained considerable attention due to their remarkably high power conversion efficiency (PCE). The Dion-Jacobson (DJ) type two-dimensional layered perovskite material, lacking interlayer van der Waals interaction, enhances device stability significantly. Simultaneously, the heterojunction structure formed by MAPbI3 improves power conversion efficiency (PCE) while maintaining high stability. This study employs 2D Dion Jacobson/3D perovskite heterojunction solar cells for further optimization through simulation analysis using SCAPS-1D (Solar Cells capacitance simulator). The intrinsic impact of heterojunction perovskite solar cells is identified, and appropriate physical parameters are adjusted to approximate experimental results. Optimization variables include absorption layer thickness, absorption layer band gap, interface defect layer thickness, back contact material, and electron transport layer material, all influencing device performance differently. Determining the ideal absorption layer thickness based on absorption characteristics, a hole-free transport layer structure is adopted in this work to reduce production costs and process complexity. To enhance the responsiveness of DJ type two-dimensional layered perovskite materials to various light wavelengths and improve PCE, the simulation employs 3D graphics to optimize variables such as the absorption layer's band gap. The highest PCE achieved is 27.42 %. Additionally, the study explores device performance in a low-temperature operating environment (265 ∼ 325 K). At 265 K, the PCE and fill factor (FF) are 29.37 % and 85.45 %, respectively, indicating that 2D Dion Jacobson/3D perovskite heterojunction solar cells exhibit structural stability and high efficiency at low temperatures compared to other PSCs. These findings suggest promising practical applications in the fields of photovoltaics and optoelectronics.

Indoor organic photovoltaic module with 30.6 % efficiency for efficient wireless power transfer

Organic photovoltaic (OPV) cells possess substantial advantages for indoor applications. However, the underdeveloped cathode interlayer hinders the industrialization of indoor OPV cells. Here, we introduce a phenanthroline derivative with weak nucleophilicity, dicarbolong-phenanthroline (DCP), as the cathode interlayer and comprehensively examine its utilization in indoor OPV cells. DCP exhibits thin depletion region width, which is beneficial for the charge extraction at the interface, thereby contributing to improved power conversion efficiency (PCE). Moreover, DCP presents high adaptability for coating process due to its thickness insensitivity. A DCP-based OPV module is fabricated by blade-coating method, reaching a high maximum output voltage of 4.00 V and a remarkable PCE of 30.6 % at 1000 lux. The OPV module can be successfully applied for efficient wireless power transfer. Furthermore, the DCP-based cell demonstrates outstanding device stability with a lifetime of 32000 hours under indoor lighting. These results demonstrate the promising potential of DCP-based OPV cells for indoor applications.

4-Methoxy phenethylammonium halide salts for surface passivation of perovskite films towards efficient and stable solar cells

Surface defects-mediated non-radiative charge recombination in polycrystalline perovskite films has been widely acknowledged to be responsible for the undesired open-circuit voltage (VOC) deficit, which is still a great challenge for perovskite solar cells (PSCs) to achieve the Shockley-Queisser efficiency limit. Herein, we report the use of 4-methoxy phenethylammonium halide salts (4-MeO-PEAX, X = I, Br, Cl) on the surface of formamidinium-cesium (FACs) perovskite films for surface passivation. The impact of halogen species in 4-MeO-PEAX on the quality of FACs perovskite films and device performance are comparatively investigated. We find that the prepared FACs perovskite films demonstrate dramatically reduced defect density and surface roughness, improved crystallinity, preferred (001) orientation and prolonged carrier lifetime after the post-treatment by 4-MeO-PEACl. Consequently, the 4-MeO-PEACl post-processed p-i-n PSCs have achieved a significantly improved power conversion efficiency of 22.63 % and VOC of 1.13 V. The unencapsulated devices post-treated with 4-MeO-PEACl maintained 90 %, 88 % and 84 % of their initial efficiencies, after being thermally stressed at 65 ℃ under dark for 312 h, stored in ambient air for 720 h and operated under continuous 1 sun equivalent illumination with maximum power point tracking at 50 ℃ for 1000 h, respectively.

Biomaterial Improves the Stability of Perovskite Solar Cells by Passivating Defects and Inhibiting Ion Migration.

With the rapid improvement of power conversion efficiency (PCE), perovskite solar cells (PSCs) have broad application prospects and their industrialization will be the next step. Nevertheless, the performance and long-term stability of the devices are limited by the defect-induced nonradiative recombination centers and ions' migration inside the perovskite films. Here, usnic acid (UA), an easy-to-obtain and efficient natural biomaterial with a hydroxyl functional group (-OH) and four carbonyl groups (-C═O) was added to MAPbI3 perovskite precursor to regulate the crystallization process by slowing the crystallization rate, thereby expanding the crystal size and preparing perovskite films with low defect density. In addition, UA anchors the uncoordinated Pb2+ and suppresses the migration of I-ions, which enhances the stability of the perovskite film. Consequently, an impressive PCE exceeding 20% was achieved for inverted structure MAPbI3-based PSCs. More impressively, the optimized PSCs maintained 78% of the initial PCE under air with high humidity (RH ≈ 65%, 25-30 °C) for 1000 h. UA can be extracted from the plant, usnea, making it inexpensive and easy to obtain. Our work demonstrates the application of the plant material in PSCs and their industrialization, which is significant nowadays.

Photochemical optimization of fluorescent dye-doped PDMS for enhanced luminescent solar concentrator performance

Luminescent solar concentrators (LSCs) that incorporate organic dyes face challenges such as self-absorption loss and aggregation-caused quenching (ACQ) as doping concentration increases, limiting the dye loading capacity. Particularly for dyes with a small Stokes shift, losses due to self-absorption or quenching are prominent even at low concentrations, hindering the attainment of high power conversion efficiency (PCE) in LSCs. Additionally, exposure of the dye-impregnated polymer matrix to oxygen, moisture, UV light, and other factors leads to a decrease in luminescence efficiency and stability due to the photooxidation reaction of the phosphor. This study presents a facile approach for enhancement of the efficiency and environmental stability of coumarin 6 (C6) dye-doped polydimethylsiloxane (PDMS) LSC through ultraviolet ozone (UVO) treatment. Photocleavage of the C6 dimer into a C6 monomer through UVO treatment leads to a significant enhancement in luminescence. Additionally, thin SiOx layers formed on both sides of the LSC not only assist in capturing luminescent light more efficiently but also block the penetration of oxygen and moisture into the LSC, resulting improved device stability. UVO-treated LSC shows approximately 32 % improvement in PCE compared to bare LSCs and exhibits significantly better stability during the 30-day long-term performance test.

Dual interfacial modification with 1D perovskite for self-assembled monolayer based inverted perovskite solar cells

Recently, self-assembled monolayer (SAM) based inverted perovskite solar cells (PSCs) have been extensively studied due to their remarkable stability and compatibility with large-area devices. Microporesat the SAM/perovskite buried interface are commonly observed, which result in the increased defect density and hindered charge extraction. Herein, a multifunctional organic material, namely 2-(methylthio)-4,5-dihydro-1 H-imidazole ammonium iodide (MTIm), is introduced as an interfacial modification material to react with the residual PbI2, forming one-dimensional (1D) (MTIm)PbI3 small grains. We found that the 1D perovskite distributes at both top and buried interfaces of PSC, achieving dual-interfacial passivation of defects. Moreover, the 1D perovskite leads to a favorable n-type doping at the top interface, and relaxes the lattice strain at the buried interface. As a result, the champion PSC device achieves significantly improved power conversion efficiency from 21.7 % to 23.8 %, and retains over 90 % of its initial PCE after storing in air for 1500 hours.

Fostering Charge Carrier Transport and Absorber Growth Properties in CZTSSe Thin Films with an ALD-SnO2 Capping Layer.

The present study demonstrates that precursor passivation is an effective approach for improving the crystallization process and controlling the detrimental defect density in high-efficiency Cu2ZnSn(S,Se)4 (CZTSSe) thin films. It is achieved by applying the atomic layer deposition (ALD) of the tin oxide (ALD-SnO2) capping layer onto the precursor (Cu-Zn-Sn) thin films. The ALD-SnO2 capping layer was observed to facilitate the homogeneous growth of crystalline grains and mitigate defects prior to sulfo-selenization in CZTSSe thin films. Particularly, the CuZn and SnZn defects and deep defects associated with Sn were effectively mitigated due to the reduction of Sn2+ and the increase in Sn4+ levels in the kesterite CZTSSe film after introducing ALD-SnO2 on the precursor films. Subsequently, devices integrating the ALD-SnO2 layer exhibited significantly reduced recombination and efficient charge transport at the heterojunction interface and within the bulk CZTSSe absorber bulk properties. Finally, the CZTSSe device showed improved power conversion efficiency (PCE) from 8.46% to 10.1%. The incorporation of ALD-SnO2 revealed reduced defect sites, grain boundaries, and surface roughness, improving the performance. This study offers a systematic examination of the correlation between the incorporation of the ALD-SnO2 layer and the improved PCE of CZTSSe thin film solar cells (TFSCs), in addition to innovative approaches for improving absorber quality and defect control to advance the performance of kesterite CZTSSe devices.

Fabrication of Erbium-Doped Upconversion Nanoparticles and Carbon Quantum Dots for Efficient Perovskite Solar Cells.

Upconversion nanoparticles (UCNPs) and carbon quantum dots (CQDs) have emerged as promising candidates for enhancing both the stability and efficiency of perovskite solar cells (PSCs). Their rising prominence is attributed to their dual capabilities: they effectively passivate the surfaces of perovskite-sensitive materials while simultaneously serving as efficient spectrum converters for sunlight. In this work, we synthesized UCNPs doped with erbium ions as down/upconverting ions for ultraviolet (UV) and near-infrared (NIR) light harvesting. Various percentages of the synthesized UCNPs were integrated into the mesoporous layers of PSCs. The best photovoltaic performance was achieved by a PSC device with 30% UCNPs doped in the mesoporous layer, with PCE = 16.22% and a fill factor (FF) of 74%. In addition, the champion PSCs doped with 30% UCNPs were then passivated with carbon quantum dots at different spin coating speeds to improve their photovoltaic performance. When compared to the pristine PSCs, a fabricated PSC device with 30% UCNPs passivated with CQDs at a spin coating speed of 3000 rpm showed improved power conversion efficiency (PCE), from 16.65% to 18.15%; a higher photocurrent, from 20.44 mA/cm2 to 22.25 mA/cm2; and a superior fill factor (FF) of 76%. Furthermore, the PSCs integrated with UCNPs and CQDs showed better stability than the pristine devices. These findings clear the way for the development of effective PSCs for use in renewable energy applications.

High‐Performance Inverted Perovskite Solar Cells by Dual Interfaces Modification with Identical Organic Salt

AbstractThe improvement of power conversion efficiency (PCE) and stability of perovskite solar cells (PSC) relies on the enhanced quality of perovskite layer and the modification of its adjacent interfaces. For this purpose, a multifunctional organic passivation molecule 1‐(4‐Fluorophenyl) biguanide hydrochloride (F‐BHCl) is introduced to the top and bottom interfaces of the perovskite layer. The PCE of PSC after the modification of double interfaces with F‐BHCl is significantly increased from 22.41% (unmodified) to 25.14%, and the storage, thermal, and operation stability is also improved. The comprehensive theoretical and experimental studies verify that due to its versatile functional groups and adaptation, F‐BHCl can significantly improve the quality of perovskite film, fully passivate several kinds of common defects, smoothen the top surfaces of perovskite film, and construct “molecular bridges” with carrier transporters on both the top and bottom surfaces, leading to significantly reduced non‐recombination and carrier transport losses. As a result, a significant increase is achieved in the open circuit voltage and fill factor as well as the whole performance of the device.

Multifunctional Hydroxylamine‐O‐Sulfonic Acid as Additives for Highly Efficient and Stable Perovskite Solar Cells

Despite the rapid development of perovskite solar cells (PSCs), defects in the devices continue to impede further improvements in power conversion efficiency and operational stability. In this work, the use of hydroxylamine‐O‐sulfonic acid as a bifunctional molecule to enhance the performance of PSCs is described. Strong coordination exists between the sulfonic acid group and uncoordinated Pb2+ of perovskite, while the NH bond on amino group interacts with uncoordinated I−. Thus, due to the synergistic contribution of sulfonic acid group and amino groups, the high‐quality perovskite film with good crystallinity and low defect density is achieved. As a result, the optimal devices exhibit an enhanced efficiency of 23.33%, which is much higher than that of the control device (21.53%). Notably, the optimized target device exhibits excellent long‐term operational stability, retaining over 90% of its initial efficiency after 480 h at 65 °C, over 93% after a continuous illumination test for 650 h, and over 96% after nearly 1400 h of air storage. In contrast, the control device demonstrates poorer stability. In these results, it is suggested that selecting a dual‐functional additive is a promising approach to enhance efficiency and maintain stability in PSCs.

Enhanced Efficiency and Stability of Wide‐Bandgap Perovskite Solar Cells Via Molecular Modification with Piperazinium Salt

AbstractWide‐bandgap (WBG) perovskite solar cell (PSC) plays a pivotal role as the top subcell in all‐perovskite tandem solar cells (TSCs), facilitating the absorption of high‐energy photons and affording a large open‐circuit voltage (VOC). Nonetheless, the stability and efficiency of WBG PSCs are constrained by light‐induced halide segregation and non‐radiative recombination losses. In this study, this work presents an approach of utilizing 2‐methylpiperazinium bromide (2‐MePBr) via interfacial engineering to realize high‐efficiency WBG (1.77 eV) PSCs. The C─NH─C functional group in 2‐MePBr, serving as an electron donor, can interact with under‐coordinated lead defects at the perovskite surface. Consequently, the treatment with 2‐MePBr mitigates interfacial non‐radiative recombination, enhances charge transport, inhibits ion migration, and thus delivers an improved power conversion efficiency (PCE) of 19.30% with a VOC of 1.29 V, and a fill factor of 83.08%. Notably, the WBG PSCs manifest enhanced stability, preserving 80% of the initial PCE after 337 h of continuous operation under 1 sun illumination at the maximum power point. Furthermore, the all‐perovskite TSCs based on this WBG subcell achieve a PCE of 27.47%, showing its promising application in perovskite‐based tandem solar cells.