High Voc Research Articles

Fluorine/bromine/selenium multi-heteroatoms substituted dual-asymmetric electron acceptors for o-xylene processed organic solar cells with 19.12% efficiency

AbstractThe development of high-performance near-infrared (NIR) absorbing electron acceptors is a major challenge in achieving high short-circuit current density (JSC) to increase power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, three new multi-heteroatomized Y-series acceptors (bi-asy-Y-Br, bi-asy-Y-FBr, and bi-asy-Y-FBrF) were developed by combining dual-asymmetric selenium-fused core and brominated end-groups with different numbers of fluorine substitutions. With gradually increasing fluorination, three acceptors exhibit red-shift absorption. Among them, bi-asy-Y-FBrF presents planar molecular geometry, the maximum average electrostatic potential, and the minimum molecular dipole moment, which are conducive to intramolecular packing and charge transport. Moreover, D18:bi-asy-Y-FBrF active layer presents higher crystallinity, more suitable phase separation, and reduced charge recombination compared to D18:bi-asy-Y-Br and D18:bi-asy-Y-FBr blends. Consequently, among theses binary OSCs, D18:bi-asy-Y-FBrF device achieves a higher PCE of 15.74% with an enhanced JSC of 26.28 mA cm−2, while D18:bi-asy-Y-Br device obtains a moderate PCE of 15.04% with the highest open-circuit voltage (VOC) of 0.926 V. Inspired by its high VOC and complementary absorption with NIR-absorbing BTP-eC9 as acceptor, bi-asy-Y-Br is introduced into binary D18:BTP-eC9 to construct ternary OSCs, achieving a further boosted PCE of 19.12%, which is among the top values for the reported green solvent processed OSCs.

Photovoltaic Efficiency Enhancement of Indium-Free Wide-Bandgap Chalcopyrite Solar Cells via an Aluminum-Induced Back-Surface Field Effect.

Wide-bandgap chalcopyrite materials are attractive candidates for a wide variety of energy conversion devices such as the top cell of tandem-type photovoltaic devices and photoelectrochemical water splitting hydrogen evolution devices. Nevertheless, simultaneous realization of high open circuit voltage (VOC) and high fill factor (FF) values has been challenging, and thus, the photovoltaic performance has been limited. In this article, high VOC and high FF values of wide-gap chalcopyrite CuGaSe2 thin-film solar cells are simultaneously demonstrated using an aluminum-induced back-surface field effect. An independently certified photovoltaic efficiency of 12.25% was obtained from an elemental In-free CuGaSe2:Al (bandgap energy ∼1.7 eV) solar cell (VOC: 0.959 V, short circuit current density: 17.64 mA cm-2, FF: 72.5%). In addition, an over 1 V-VOC CuGaSe2 cell (FF: 74.5%) was obtained even with the use of a conventional CdS buffer layer. Although incorporation of aluminum often leads to degradation of the chalcopyrite solar cell performance, the addition of a small amount of aluminum is found to be effective in enhancing wide-gap chalcopyrite photovoltaic performance.

Completely Fused Non‐Fullerene Acceptor Enables Efficient Postprocessing‐Free Organic Photovoltaics Cells

AbstractThe photovoltaic performance of organic photovoltaic (OPV) cells can be significantly improved by regulating the aggregation structure and film formation kinetics of the constituent materials. However, many regulation strategies, including the use of additives and annealing, require complex fabrication processes and additional investments, which poses challenges for the industrialization of OPV cells. In this work, a completely fused non‐fullerene acceptor, GS‐20 is designed and synthesized, with strong aggregation properties. The incorporation of GS‐20 as a third component into the PBQx‐TF:eC9‐2Cl‐based cell accelerates aggregation of eC9‐2Cl and improves molecular stacking by promoting film deposition. The as‐cast ternary OPV cells fabricated without any post‐treatments exhibited a high VOC of 0.890 V and a maximum PCE of 19.0%. Moreover, a postprocessing‐free OPV module is fabricated using the blade coating method and obtains a satisfactory PCE of 13.5%, indicating excellent feasibility for large‐scale preparation. This work realizes an efficient postprocessing‐free OPV cell through molecular design and ternary strategy, facilitating the industrialization of OPV technology.

Performance of Triple-Cation Perovskite Solar Cells under Different Indoor Operating Conditions.

We systematically analyze triple-cation perovskite solar cells for indoor applications. A large number of devices with different bandgaps from 1.6 to 1.77 eV were fabricated, and their performance under 1-sun AM1.5 and indoor white light emitting diode (LED) light was compared. We find that the trends agree well with the detailed balance limit; however, the devices near the optimal bandgap (1.77 eV) perform worse due to the lower perovskite quality. Instead, we achieve the highest power conversion efficiency (PCE) of 34.0% under 870 lx with 1.67 eV and Al2O3 passivation. The perovskite with a bandgap of 1.71 eV is not far behind, with a high VOC of 1.02 V. Measurements under different white LED color temperatures confirm that the highest PCE is achieved under the warmest colors. All measurements were carried out in a dedicated indoor setup that ensures the diffuse light typical of indoor environments and allows both short- and long-term measurements. In the best case, we observe no degradation during the 33-day test under simulated office conditions with regular switching on and off of the light and a T80 of 30 days under continuous illumination. The results were obtained from multiple batches, which corroborates our findings and gives them statistical relevance.

Reaction kinetics and isotherms of commercial activated carbon in variable pressure adsorption of high compound VOCs

ABSTRACT This study investigated the feasibility of using/reusing commercial activated carbon (CAC) for the capture of high molecular weight and high-boiling point volatile organic compounds (HBPVOCs). The CAC was first characterized using proximate analysis, heat value analysis, iodine value analysis, element analysis, inductively coupled plasma spectrometry, and specific surface area analysis. We then assessed the adsorption/desorption performance of a CAC-based PSA system for the removal of Butyl Cellosolve (BCS), a HBPVOC commonly used in paints, coatings, cleaners, and industrial processes. This involved deriving the BCS adsorption capacity of CAC as a function of adsorbent quantity (2.5, 5, and 10 g), flow rate (4, 6, and 8 L/min), and pressure (1.3, 2.3, and 3.4 kg/cm2). The BCS adsorption capacity of the CAC varied with pressure as follows: 1.3 kg/cm2 (652.85 mg/g), 2.3 kg/cm2 (817.20 mg/g) and 3.4 kg/cm2 (1324.05 mg/g). The adsorption mode most closely resembled pseudo-first-order kinetics (i.e. single-layer physical adsorption). Desorption was performed using an adjustable tubular high-temperature furnace under a nitrogen atmosphere (0.93 kg/cm2). Following desorption with a set desorption duration of 1 hr, the BET values varied with temperature as follows: 350°C (75.58% of the original value) and 450°C (86.04% of the original). Desorbed CAC (DCAC) was also examined to detect changes in pore structure due to the effects of recycling. We obtained breakthrough curves and adsorption capacity curves of CAC as functions of flow rate and pressure. We also investigated adsorption performance under pressure swing conditions from the perspective of reaction kinetics and density functional theory. Our results demonstrate the efficacy of CAC in the adsorption of BCS as well as the recyclability of this material. Implication Statement This study demonstrates the potential for reusing commercial activated carbon (CAC) to capture high molecular weight and high-boiling point volatile organic compounds (HBPVOCs). Through comprehensive characterization and performance evaluation, we found that CAC effectively adsorbs Butyl Cellosolve (BCS), a common industrial solvent, with adsorption capacity increasing with pressure. The adsorption process follows pseudo-first-order kinetics, indicating single-layer physical adsorption. Additionally, the study highlights the recyclability of CAC, as desorption and subsequent analysis revealed minimal changes in pore structure, maintaining a significant portion of its original BET value. These findings suggest that CAC is not only effective for BCS adsorption but also sustainable for repeated use, offering an efficient and eco-friendly solution for managing industrial HBPVOCs.

Bacterial dynamics and volatile metabolome changes of vacuum-packaged beef with different pH during chilled storage

This study aimed to assess the growth of spoilage bacteria in Brazilian vacuum-packed beef across different pH ranges (5.4–5.8, 5.8–6.1, ≥6.1) stored at temperatures of 0 °C, 4 °C, and 7 °C. Additionally, the research sought to identify predominant spoilage bacteria at the genus level using 16S rDNA gene sequencing and analyze the principal volatile organic compounds (VOCs) produced by this microbiota through HS-SPME/GC–MS. Lactic acid bacteria (LAB) consistently exhibited counts exceeding 6.0 Log CFU/g, regardless of temperature and pH conditions. The bacterial diversity in the meat samples reflected the influence of slaughterhouse environments, with Pseudomonas and Serratia remaining dominant across different cuts and pH levels. Post-storage, variations in pH and temperature modulated the initial bacterial diversity, leading to a reduction in diversity and an increase in LAB such as Lactobacillus, Lactococcus, Leuconostoc, and Carnobacterium. Notably, these changes were observed within pH ranges of 5.4–5.8 and 5.8–6.1, irrespective of beef cuts and storage temperatures. Based on high throughput sequencing and VOCS, correlation analysis revealed a relationship between the growth of specific spoilage microorganisms under vacuum conditions and the presence of VOCs such as alcohols (e.g., 1-propanol, 2-methyl-) and ketones (e.g., 2-nonanone, 2-octanone, 2-heptanone), identifying them as potential indicators of spoilage bacteria growth.

Synergistic Passivation of Bulk and Interfacial Defects Improves Efficiency and Stability of Inverted Perovskite Solar Cells

Defects both in bulk and at the interfaces serve as charge trapping sites for nonradiative recombination and as ion migration pathways, resulting in degradation of perovskite solar cell efficiency and stability. In this work, a strategy for simultaneous passivation of both bulk and interfacial defects is reported. For bulk passivation polystyrene (PS) is used as an additive in the perovskite precursor which reduces the structural defects by forming larger defect‐free grains. While the F‐PEAI cation is used to passivate the interfacial defects, present at both perovskite HTL/ETL interfaces. Furthermore, by conducting control measurements with just bulk modification (PS), just interface modification (F‐PEAI), and a combination of both, the role of individual defect passivation strategies is decoupled. As a result of simultaneous bulk as well as interfacial passivation, the modified perovskite solar cell shows the highest efficiency of 22.32% with a high Voc of 1.14 V and fill factor of 80%. Moreover, the cells have excellent stability retaining 92% and 99% of their initial efficiency after 1008 h and 560 h under ISOS‐ D1 and D2 storage conditions. These results highlight the importance of simultaneous bulk and interfacial passivation for improving solar cell efficiency and stability.

Non‐Electron Withdrawing Unit Copolymerization to Enhance Photo‐Stability of Thiophene‐Based Organic Solar Cells

The impact of non‐electron withdrawing unit copolymerization on photostability of fullerene‐based organic solar cells is investigated using two donor polymers namely: benzodithiophene‐4,8‐dione (BDD) unit copolymerized with α‐quaterthiophene (4 T) unit (PBDD4T) and poly‐3‐hexyl‐thiophene (P3HT). The optical and electrochemical properties of the polymers reveal a deeper highest occupied molecular orbital (HOMO) and broader absorption in PBDD4T in comparison to P3HT owing to the BDD copolymerization. The copolymer achieves a higher power conversion efficiency (PCE) compared to the P3HT‐based device due to its higher VOC and Jsc that resulted from its deeper HOMO level and broader absorption. The photostability study reveals that PBDD4T‐based devices lost 14% of its initial PCE relative to the 48% reduction in PCE for P3HT‐based devices after 7 h of irradiation. Further investigation into the reasons behind the difference in the photostability suggests that photooxidation and recombination induced by irradiation in PBDD4T‐based devcie are suppressed by BDD‐copolymerization, maintaining better stability. In contrast, P3HT:PC71BM‐based solar absorber shows bimolecular recombination due to photoaging processes, which have negatively impacted the device stability. The reduction in stability of both devices is evident by lower photogenerated current attributed to reduced charge mobility and increased surface roughness.

Implementation of Regenerative Thermal Oxidation Device Based on High-Heating Device for Low-Emission Combustion

In this paper, a heating device is implemented by considering two large factors in a 100 cmm RTO design. First, when the combustion chamber is used for a long time with a high temperature of 750–1100 °C depending on the high concentration VOC gas capacity, there is a problem that the combustion chamber explodes or the function of the rotary is stopped due to the fatigue and load of the device. To prevent this, the 100 cmm RTO design with a changed rotary position is improved. Second, an RTO design with a high-heating element is implemented to combust VOC gas discharged from the duct at a stable temperature. Through this, low-emission combustion emissions and energy consumption are reduced. By implementing a high heat generation device, the heat storage combustion oxidation function is improved through the preservation of renewable heat. Over 177 h of demonstration time, we improved the function of 100 cm by discharging 99% of VOC’s removal efficiency, 95.78% of waste heat recovery rate, 21.95% of fuel consumption, and 3.9 ppm of nitrogen oxide concentration.

Efficient wide-bandgap perovskite photovoltaics with homogeneous halogen-phase distribution

Wide-bandgap (WBG) perovskite solar cells (PSCs) are employed as top cells of tandem cells to break through the theoretical limits of single-junction photovoltaic devices. However, WBG PSCs exhibit severe open-circuit voltage (Voc) loss with increasing bromine content. Herein, inhomogeneous halogen-phase distribution is pointed out to be the reason, which hinders efficient extraction of carriers. We thus propose to form homogeneous halogen-phase distribution to address the issue. With the help of density functional theory, we construct a double-layer structure (D-2P) based on 2-(9H-Carbazol-9-yl)ethyl]phosphonic acid molecules to provide nucleation sites for perovskite crystallization. Homogeneous perovskite phase is achieved through bottom-up templated crystallization of halogen component. The efficient carrier extraction reduces the Shockley-Read-Hall recombination, resulting in a high Voc of 1.32 V. As a result, D-2P-treated device (1.75 eV) achieves a record power conversion efficiency of 20.80% (certified 20.70%), which is the highest value reported for WBG (more than 1.74 eV) PSCs.

Tailoring Perovskite/C60 Interface by Reactive Passivators for Stable Tandem Solar Cells

AbstractIntegrating perovskite solar cells with crystalline silicon bottom cells in a monolithic two‐terminal tandem configuration enables power conversion efficiency (PCE) surpassing the theoretical limits of single‐junction cells. However, wide bandgap (WBG) perovskite films face challenges related to phase stability and open circuit voltage (VOC) deficit, particularly due to severe non‐radiative recombination at the perovskite/C60 interface. Here, the interfacial defects are passivated by incorporating a reactive passivator that reacts with lead halides to form low‐dimensional phases. The target product obtained by optimizing the reaction temperature not only suppresses recombination across the interface, but also facilitates the transfer of charge carriers. More importantly, this product can suppress phase segregation of WBG perovskite films under exposure to light illumination and moisture. This strategy enables a high VOC of 1.25 V for WBG perovskite device based on polymer hole transport layer and a certified stabilized PCE of 30.52% for a monolithic perovskite/silicon tandem solar cell. The unencapsulated tandem device retains 94% of its initial PCE over 200 h under continuous 1‐sun full spectrum illumination in air, demonstrating the improved phase stability.

Large‐Area Flexible Organic Photovoltaic Modules on Smoothened Silver Nanowire Transparent Electrodes with Thick Electron Transporting Layer

AbstractHigh‐efficiency large‐area flexible organic photovoltaic (OPV) modules are still challenging. Electrical shunt and shortage generally occur due to surface roughness or spikes that result in low efficiency. In this work, a thick electron transporting layer (ETL) of zinc‐chelated polyethylenimine (PEI‐Zn) is introduced to smoothen the surface of silver nanowires (AgNWs) transparent electrodes. The smoothened surface of AgNWs electrodes helped to suppress the electrical leakage or shortage. Thicker PEI‐Zn layers are required to overcome the open‐circuit voltage (VOC) loss when the device area increases. For large‐area OPV modules on AgNWs electrodes, a high thickness of PEI‐Zn up to 350 nm can deliver high VOC as well as power conversion efficiency (PCE). Based on the AgNWs transparent electrode coated by thick PEI‐Zn ETL, a PCE of 12.50% is achieved for 35.2 cm2 flexible OPV modules certified by a third party. The modules exhibited good illumination stability and mechanical flexibility.

Uniform Phase Permutation of Efficient Ruddlesden-Popper Perovskite Solar Cells via Binary Spacers and Single Crystal Coordination.

2D Ruddlesden-Popper perovskites (RPPs) have attracted extensive attention in recent years due to their excellent environmental stability. However, the power conversion efficiency (PCE) of RPP solar cells is much lower than that of 3D perovskite solar cells (PSCs), mainly attributed to their poor carrier transport performance and excessive heterogeneous phases. Herein, the binary spacers (n-butylammonium, BA and benzamidine, PFA) are introduced to regulate the crystallization kinetics and n-value phase distribution to form uniform phase permutation of RPP films. The study then incorporates n = 5 BA2MA4Pb5I16 memory single crystal to achieve ultrafast stepped-type carrier transport from the low n-value phases to the high n-value phases in the high-quality (BA0.75PFA0.25)2MA4Pb5I16 films. These binary spacers and single-crystal-assisted crystallization strategies produce high-quality films, leading to fast carrier extraction and significant nonradiative recombination suppression. The resulting PSC presents a champion PCE of 21.15% with an impressive open circuit voltage (VOC) of 1.26V, which is the record high efficiency and VOC for low n-value RPP solar cells (n ≤ 5).

Enhanced Electric Field Minimizing Quasi-Fermi Level Splitting Deficit for High-Performance Tin-Lead Perovskite Solar Cells.

The quasi-Fermi level splitting (QFLS) deficit caused by the non-radiative recombination at the interface of perovskite/electron transport layer (ETL) can lead to severe open-circuit voltage (VOC) loss and thus decreases the efficiency of perovskite solar cells (PSCs), however, has received limited attention in inverted tin-lead PSCs. Herein, the strategy of constructing an extra-electric field is presented by introducing ferroelectric polymer dipoles (FPD)-β-poly(1,1-difluoroethylene)-to suppress the QFLS deficit. The directional polarization of FPD can enhance the built-in electric field (BEF) and thus promote the charge transfer at the perovskite/ETL interface, which effectively suppresses non-radiative recombination. Furthermore, the incorporation of FPD facilitates high-quality crystallization of perovskite and reduces the surface energetic disorder. Therefore, the QFLS deficit in the perovskite/ETL half-stacked device is reduced from 62 to 27 meV after incorporating FPD, and the optimized device achieves an efficiency of 23.44% with a high VOC of 0.88V. Additionally, the addition of FPD increases the activation energy for ion migration, which can reduce the effect of ion migration on the long-term stability of the device. Consequently, the FPD-incorporated device retains 88% of the initial efficiency after 1100h of continuous illumination at the maximum power point (MPP).

Optimizing strategy of bifacial TOPCon solar cells with front-side local passivation contact realized by numerical simulation

The tunnelling oxide passivation contact (TOPCon) solar cells have been impressive in the global photovoltaic (PV) market originating from their high efficiency and stability. However, it exhibits significant recombination losses due to its boron diffusion, laser damage and metal-semiconductor contact on front side. The bifacial TOPCon structure demonstrates massive potential in the improvement of passivation and contact performance with the premise that it can solve the parasitic absorption of polycrystalline silicon (poly-Si). In this study, the localized poly finger structure with excellent optics and passivation performance is designed in the front side of bifacial solar cells to compare with traditional TOPCon and full-area poly passivation devices. The theoretical efficiency and detailed power loss analysis in our simulation reveal that suppressing the recombination of FSF (front surface field) and the contact area is the crucial strategy to improve device performance, with optimized efficiency of 26.62 % and FF of 85.16 %. These results indicate that the route of BJ (back junction) structure containing localized selective contact and full coverage high-quality passivation holds potential in realizing both high Jsc and Voc for FBC (front and back contact) solar cells, featuring great instructive significance for future industrialization of PV production.

Correlating Chemical Structure and Charge Carrier Dynamics in Phenanthrocarbazole‐Based Hole Transporting Materials for Efficient Perovskite Solar Cells

ABSTRACTPolymeric hole transport materials (HTMs) have emerged because of their potential to produce dopant‐free, efficient, and stable perovskite solar cells (PSCs). Therefore, we engineered 10 novel donor materials (SMH1–SMH10) containing phenanthrocarbazole‐based polymeric structures for organic and PSCs. These molecules underwent bridging‐core modifications using different spacers, such as furan (N1), pyrrole (N2), benzene (N3), pyrazine (N4), dioxane (N5), isoxazole (N6), isoindole (N7), indolizine (N8), double bond (N9), and pyrimidine (N10), in comparison to reference molecule R. The study examined the structure–property relationship and the impact of these modifications on the optical, photovoltaic, photophysical, and optoelectronic characteristics of the newly designed SMH1–SMH10 series. Density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) calculations were conducted to analyze frontier molecular orbitals, density of states, reorganization energies, open‐circuit voltage, transition density matrix, and charge transfer processes. Results show that the newly designed molecules (SMH1–SMH10) exhibited superior optoelectronics characteristics compared to the R molecule. Among these, SMH4 is the most promising candidate, with a small band gap (2.79 eV), low electron and hole mobility (λe 0.0028 eV, λh 0.0020 eV), lower binding energy (Eb 0.58 eV), high λmax values (656.42 nm in gas, 573.34 nm in chlorobenzene), and a high Voc of 1.30 V. Therefore, this study demonstrated that bridging‐core modifications offer a simple and effective strategy for designing desirable characteristics molecules for photovoltaic applications.

Atom layer deposited TiO2 electron transport layer for silicon heterojunction solar cells to achieve high performance

Silicon/compound heterojunction (SCH) solar cells based on p-type and n-type c-Si wafers using atom layer deposition-TiO2 and low work function metal as the electron transport layer and rear electrode are fabricated. Efficiencies of 20.6 % and 21.6 % are achieved on p-type and n-type silicon solar cells, respectively. High Voc exceeding 700 mV have been realized on both kinds of Si wafers. Special attention has been paid to the SCH solar cells based on p-type c-Si wafers in which the TiO2 electron transport layer serves as the emitter. Carrier transport mechanisms and junction characteristics of the SCH solar cells are analyzed based on dark J-V measurement. The formation of a strong inversion layer at the Si surface region is determined, which implies the high Voc potential of the SCH solar cells based on p-type Si. An optical loss analysis is performed along with a possible solution to further improve the Jsc. The feasibility of TiO2 applied as an efficient electron transport layer (emitter) in p-type SCH solar cells with high performance has been showed.

Current matching and filtered spectrum analysis of wide-bandgap/narrow-bandgap perovskite/CIGS tandem solar cells: A numerical study of 34.52 % efficiency potential

Perovskite (PVK) materials with wide-bandgap (WBG) play a crucial role in achieving high-performance tandem devices but phase segregation and open-circuit voltage (VOC) loss hinders in surpassing the efficiency of single-junction solar cells. Present work discloses a numerical simulation which has been carried out using a WBG material CH3NH3PbI3-xClx of bandgap (Eg) 1.65eV as an absorber layer of the top cell (TCELL) and a Cu(In,Ga)Se2-based cell having narrow-bandgap (NBG) of Eg (1.27eV) has been used as bottom cell (BCELL). The TCELL utilizes polyethyleneimine ethoxylated (PEIE) interfacial layer to promote charge-collection and charge-tunneling. The TCELL and BCELL have been optimized by various optimization processes such as simultaneous thickness variation of active-region with defect density (DD), variation of interface defect density (IDD) with solar-cell parameters a commendable power conversion efficiency (PCE) of 27.06 %, and 26.77 % has been achieved for respective solar-devices. Variations of numerous electron transport layer (ETL) and hole transport layer (HTL) have also been performed to acquire highly optimized TCELL. Thus, a perovskite/CIGS tandem solar cell (PVK/CIGS-TSC) device has been obtained using filtered-spectra analysis and current-matching (method which display a promising photovoltaic (PV) parameter with a high VOC of 2.29 V, short-circuit current density (JSC) of 17.41 mA/cm2, fill factor (FF) of 86.45 % and PCE of 34.47 %. These discoveries hold significant promise for the future development of TSCs.

Machine learning for screening and predicting the best surface modifiers for a rational optimization of efficient perovskite solar cells

The key to keep the rising slope of perovskite solar cell performances is to reduce non-radiative losses by minimizing defect density. To this end, a large variety of strategies have been adopted spanning from the use of interfacial layers, surface modifiers, to interface engineering. Although winning concepts have been demonstrated, they result from a mere trial and error approach, which is time consuming and operator-dependent. To face this challenge, in this work, we propose the use of a machine learning approach for an educated and rational material screening with optimal characteristics in terms of surface passivation. In particular, we applied Shapley additive explanation to extract the specific chemical features of the passivator, which directly impact the device parameters, specifically the open circuit voltage (Voc). By monitoring the different material parameters as input, we were able to list the most promising passivators and directly test them in working solar cells. By comparing the device performances with the results of the modeling and with additional optical and morphological characterization, we retrieved the most significant material properties linked to the highest efficiency, which are (i) the presence of chlorine and its strong binding capacity to positively charged defects on perovskite surface, reducing the non-radiative recombination and (ii) an increased flexibility of the molecule, resulting in better coverage of the surface. Finally, we tested the predictive power of the ML algorithm proposing a new passivator, which, implemented in a working device, leads to the predicted high Voc confirming the results of the modeling.

High Open-Circuit Voltage Wide-Bandgap Perovskite Solar Cell with Interface Dipole Layer.

Wide-bandgap perovskite solar cells (PSCs) with high open-circuit voltage (Voc) represent a compelling and emerging technological advancement in high-performing perovskite-based tandem solar cells. Interfacial engineering is an effective strategy to enhance Voc in PSCs by tailoring the energy level alignments between the constituent layers. Herein, n-type quinoxaline-phosphine oxide-based small molecules with strong dipole moments is designed and introduce them as effective cathode interfacial layers. Their strong dipole effect leads to appropriate energy level alignment by tuning the work function of the Ag electrode to form an ohmic contact and enhance the built-in potential within the device, thereby improving charge-carrier transport and mitigating charge recombination. The organic interfacial layer-modified wide-bandgap PSCs exhibit a high Voc of 1.31V (deficit of <0.44V) and a power conversion efficiency (PCE) of 20.3%, significantly improved from the device without an interface dipole layer (Voc of 1.26V and PCE of 16.7%). Furthermore, the hydrophobic characteristics of the small molecules contribute to improved device stability, retaining 95% of the initial PCE after 500h in ambient air.