Improved Power Conversion Efficiency Research Articles

Revealing Defect Passivation and Charge Extraction by Ultrafast Spectroscopy in Perovskite Solar Cells through a Multifunctional Lewis Base Additive Approach

Defect passivation inside the crystal lattice and the grain‐boundary (GB) surface of the perovskite films has become the most effective strategy to suppress the negative impact of the nonradiative recombination in perovskite solar cell. In this study, a unique approach to effectively passivate the defect states of MAPbI3 perovskite thin film using thionicotinamide (TNM) as a multifunctional Lewis base additive is demonstrated. TNM as an additive with three different types of Lewis base sites, i.e., pyridine, amino, and CS functional groups, is introduced to mitigate the trap states in the TNM‐modified perovskite films and thoroughly investigate the passivation defects. The nonbonded electron of the three different Lewis base sites can synergistically passivate the antisite lead (Pb) defects and improve the stability of the device. In addition, the NH2 group can form ionic bonds with negatively charged I– ions and inhibit ion migration caused by them. It is found that such passivation effect of TNM reduces the GB defects and improves the crystallinity significantly. As a result, a champion TNM‐modified device shows an improved power conversion efficiency of 19.26% from 16.86% along with enhanced open‐circuit voltage, fill factor, and negligible hysteresis.

A multifunctional interlayer between mesoporous TiO2 and perovskite for perovskite solar cells with high efficiency and stability

The industrialization of the perovskite solar cells (PSCs) requires further lifting their power conversion efficiency (PCE). There are some important factors to hinder the PCE improvement, such as interface defects and energy level mismatching betwee electron transport layer (ETL) and perovskite layer, and solar energy loss due to no absorption of near infrared (NIR) for the perovsktie. Thus in this study, a multifunctional material of W-Er-Yb doped TiO2 (W-UC-TiO2) was prepared and applied to PSCs as an interlayer between mesoporous TiO2 and perovskite. The experimental results demonstrate that the interlayer of W-UC-TiO2 has the functions of improving NIR absorption for PSCs, passivating inerface defects and improving energy level matching between TiO2 and perovskite. A high efficiency of 21.32% was acquired for the PSCs with W-UC-TiO2 interlayer from 19.26% for the control device. Moreover, stability of the PSCs was improved by the insertion of W-UC-TiO2 interlayer.

Amphipathic Astaxanthin Additive for Low Voltage-loss Perovskite Solar Cells With Enhanced Quasi-Fermi Level Splitting and Solar Hydrogen Production Application.

Even though the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is nearly approaching the Schottky-Queisser limit, low open-circuit voltage (Voc) and severe Voc loss problems continue to impede the improvement of PCEs. Astaxanthin (ASTA) additive is introduced in the formamidinium lead triiodide (FAPbI3)perovskite film as an additive, which can facilitate the transportation of charge carriers and interact with Pb2+ by its distinctive groupings. Furthermore, the addition of ASTA decreases the defect's active energy, regulates the deep-level defect by filling up the grain boundaries (GBs), and promotes the crystallization of perovskite film. Remarkably, an enhanced quasi-Fermi level splitting (QFLS) of 1.164eV and a reduced Voc loss of only 96mV are realized. The champion PCE of 24.56% is attained by ASTA-modified PSCs on the basis of 22.75% PCE. Moreover, the PSCs that underwent ASTA modification demonstrate improved operational stability, ensuring consistent output in real-world scenarios. Furthermore, PSCs with an active area of 1 cm2 are used for water electrolysis to produce hydrogen and exhibit a PCE of 22.41%. This work offers an environmentally benign solution to address the inherent issues of FAPbI3 PSCs and lays the groundwork for the development of a prospective solar hydrogen production application.

Design and simulation of bifacial perovskite solar cell with high efficiency using cubic plasmonic nanoparticles

Bifacial perovskite solar cells (Bi-PSCs) are gaining attention for their ability to exceed the efficiency limits of traditional single-junction cells by absorbing light from both the front and rear surfaces. This study explores a novel approach to boost the efficiency and stability of Bi-PSCs by integrating clusters of cubic metallic nanoparticles (NPs) within the absorber layer. These plasmonic NPs, embedded in the middle of the absorber layer, significantly enhance light absorption, resulting in substantial improvements in power conversion efficiency for both front and rear irradiation. Our three-dimensional simulations demonstrate that incorporating Ag-based NPs can achieve efficiency enhancements of 29.89 % (from 18 % to 23.39 %) for front irradiation and 29.63 % (from 17.22 % to 22.33 %) for rear irradiation. Ag-based NPs exhibit the most notable efficiency improvement, reaching a short-circuit current of 41.30 mA/cm2 and an efficiency of 35.34 % at an albedo of 0.5. To address potential issues such as corrosion and degradation of the perovskite material, the metallic NPs are encapsulated with a thin dielectric nano-shell of SiO₂. This encapsulation strategy effectively prevents degradation, ensuring the long-term stability of the Bi-PSCs. The results indicate that the use of clusters of cubic metallic NPs, combined with dielectric encapsulation, offers a superior approach to optimizing the performance and stability of Bi-PSCs, providing a more efficient alternative to increasing the absorber layer’s thickness.

Minimizing voltage loss for perovskite solar cells via synergistically passivating defects and reinforcing interfacial electric field

Perovskite solar cells have attracted much attention because of their excellent photoelectric properties. However, non-radiative recombination losses due to interface defects limit the open circuit voltage (Voc) of PSCs, which prevents further improvement in power conversion efficiency (PCE). To solve this problem, we introduced Li2SO4 into the SnO2/perovskite interface to obtain a higher Voc through interfacial passivation and enhancement of the interface electric field. Herein, Li+ presents bottom-up diffusion into perovskite surface, and forms dipoles with FA to enhance the interface electric field. Furthermore, SO in SO42- passivates Sn4+ on the surface of SnO2 and Pb2+ at the buried interface of perovskite. This method combines interfacial passivation with synchronous electric field enhancement, which promotes interfacial carrier migration and reduces non-radiative recombination and voltage loss (Vloss) at the interface. As a result, the SLS-device exhibits an enhanced Voc of 1.25 V, with a very low Vloss of 0.33 V, achieving an outstanding PCE of 24.31 %. Moreover, the device maintained 90 % of the initial PCE after exposure to ambient air for 1000 h. This work demonstrates the necessity to co-design the interface microstructure and electric field distribution for reducing the energy loss of perovskite photovoltaic devices and promoting the efficiency of interfacial charge transport.

The significance of bilayer window (CdS:O/CdS) on the performance of CdTe thin film solar cells

Ultrathin and compact CdS:O/CdS bilayer window in CdTe solar cells has higher potential for enhanced p-type doping, reduced Te diffusion, and improved power conversion efficiency (PCE) compared to traditional single-layer CdS or CdS:O windows. In this effort, we used a two-gun RF sputtering equipment to deposit compact CdS:O(∼50 nm)/CdS(∼50 nm) bilayers onto the borosilicate and ITO-coated glass substrates at low temperature (≤ 250 oC). Intriguingly CdS:O/CdS bilayers retain its hexagonal {0002} preferential orientation but with around 10.58% optical bandgap (Eg) increment compared to CdS (Eg≈2.32 eV) of equal thickness (∼100 nm). Close-spaced sublimation (CSS) technique was used to deposit the CdTe thin film onto the CdS and CdS:O/CdS layers at 550 °C. The effect of CdS and CdS:O/CdS layers on the microstructural and morphological features of CdCl2-treated CdTe films were critically analyzed revealing a promising {0001}/{111}-like partial-epitaxy presumably due to the preferential cubic CdTe growth along the <111> orientation. The CdTe films grown over a CdS:O/CdS layer exhibited smaller average crystallite and grain sizes than those grown over a single CdS layer. An essential finding was the formation of an optimal intermix layer of CdSxTe1-x, particularly evident in the CdTe films grown on the CdS:O/CdS bilayer. To comprehensively explore the effect of CdS:O/CdS window layers on PCE, complete CdTe solar cells were fabricated using three different window layers: CdS, CdS:O, and CdS:O/CdS, which are all considered as rudimentary as no layer optimization was performed. Notably, CdTe solar cell that incorporates the CdS:O/CdS bilayer window exhibited the most promising performance among all the tested rudimentary cells and corroborated the numerically simulated findings conducted by the SCAPS-1D simulator.

Tin oxides@stannous pyrophosphate colloidal quantum dots as multifunctional electron transporting layer for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) are anticipated to spearhead the revolution in solar energy technology. Engineering the electron transporting layer (ETL)/perovskite heterointerface is known to be a key point for further high-performance PSCs because it determines the main charge transporting and energy losses. However, the most advanced SnO2 colloidal precursors tend to exhibit agglomeration and structural flaws, thereby deteriorating the morphology and electronic mass of the obtained ETL. Here, we polished the microstructure of the SnO2 surface by self-assembling SnO2@Sn2P2O7 quantum dots (SPOS), which is synthesized by the chemical reaction between hypophosphoric acid (H3PO2) and SnO2. The Sn2P2O7 was synthesized on the SnO2 surface, terminating the surface dangling bonds and resulting in steady SPOS quantum dots with smooth microstructure. The SPOS ETL with good optical and electrical properties as well as matched bandgap alignment with perovskite, yielding an improved power conversion efficiency of 23.35% for PSCs. Moreover, due to the suppression of defect-induced deprotonation reactions, the SPOS-PSCs exhibit favorablelongstability than the SnO2-PSCs. This work demonstrates that the surface reconstruction of the ETL is crucial for enhancing the power conversion efficiency and stability of PSCs.

First-principle study of the ground-state crystal structure and optoelectronic response of CsPbX3 (X= Cl, Br, I) for photovoltaic applications

The optoelectronic response and ground state crystal structure of tetragonal (P4/mbm), orthorhombic (Pmnb) and monoclinic (P21/m) phases of CsPbX3 (X = Cl, Br, I) are studied for optoelectronic applications using first principle simulations. Electric field gradient (EFG) and magnetic hyperfine interactions are investigated to explore the charge distributions surrounding the nucleus and local magnetic environment of the atomic nucleus. The orthorhombic phase of these compounds is more stable having lowest ground-state energy compared to tetragonal and monoclinic phases. The understudied halide perovskites have direct band gap nature and spin orbit coupling (SOC) effect splits Pb-p and X-p orbitals at the edges of conduction and valence band (CB and VB) respectively. At the edge of VB, the strongly hybridized X-p and Pb-p orbital and direct band gap nature of CsPbX3 is excellent for the light absorption and photovoltaic (PV) applications. The n-i-p configuration (FTO/ETL/CsPbX3/HTL/Au) of the simulated structure shows that CsPbI3 has improved power conversion efficiency (PCE) of 22.48 % and 22.32 % and quantum efficiency (QE) about ∼80 % in tetragonal and monoclinic phases respectively. The Pb and Cs values of EFG tensor in z-direction (Vzz) are close to each other, which show that the distribution of electronic charge density is similar near these nuclei. Moreover, Cs-s orbital has negligible contribution and Pb-p and I-p orbitals have higher contribution in the hyperfine field (HFF). The negative HFF indicates the opposite HFF contribution.

Enhancing the efficiency of lead-free Cs2AgBiBr6 based double perovskite solar cells with optimizing ETLs and HTLs using SCAPS-1D

This study introduces a tin-free, stable, lead-free, double perovskite solar cell device with improved power conversion efficiency (PCE). Different electron transporting layers (ETLs) including IGZO, AZO, LBSO, and TiO2 and hole transporting layers (HTLs) as Cu2O, CNTS, ZnTe, and P3HT are considered for optimization with Cs2AgBiBr6 and fluorine-doped tin oxide as double perovskite layer and substrate respectively. The effect of various device parameters on the device performance has been studied. The device configuration of FTO/AZO/Cs2AgBiBr6/ZnTe achieves a PCE of 26.89 %, fill factor (FF) of 83.87 %, open-circuit voltage (VOC) of 1.50 V, and short-circuit current (JSC) of 21.35 mA/cm2.

Investigating the influence of Al2O3 doping on TiO2 optoelectronic properties and charge separation efficiency

In this study, Aluminum oxide (Al2O3) was utilized as a dopant in the crystal structure of titanium dioxide (TiO2) to enhance the photovoltaic efficiency of n-i-p type organic solar cells. These solar cells were fabricated using a thin film of TiO2 doped with Al2O3, serving as the electron transport layer. TiO2 thin films were synthesized using different Al2O3 concentrations (0 %, 0.25 %, 0.5 %, and 1 % w/V) through the spin-coating technique. A blend of poly(3-hexylthiophene) and phenyl C61-butyric acid methyl ester (P3HT:PC61BM) was spin-cast at 600 rpm for 30 s, forming the solar cells active layer. Organic solar cells with an n-i-p structure were constructed, following the configuration FTO/TiO2:Al2O3/P3HT:PC61BM/MoO3/Ag. Investigations have been conducted to examine how varying concentrations of Al2O3 doping affect the photovoltaic performance of the solar cells. The power conversion efficiency (PCE) of the produced solar cells showed an increase from 2.74 % to 3.53 % at a 0.5 % Al2O3 doping concentration. The solar cells performance has been improved by adjusting the concentration of Al2O3. The findings show that the addition of Al2O3 to TiO2 films improves power conversion efficiency.

(Invited) Photoelectrode Design for Photoelectrocatalytic Hydrogen Production

Semiconductor nanomaterials hold the keys for efficient solar energy harvesting and conversion processes like photocatalysis and photoelectrochemical reactions. In this talk, we will give a brief overview of our recent progress in designing semiconductor nanomaterials for photoelectrochemical energy conversion including solar hydrogen generation and low-cost solar cells. In more details, we have been focusing on a few aspects; 1) photocatalysis mechanism, light harvesting, charge separation and transfer and surface reaction engineering of low-cost metal oxide based semiconductors including TiO2, BiVO4 as efficient photoelectrode for photoelectrochemical hydrogen production; 2). The design of ultra-stable composites of perovskite-MOF with improved light emitting and photocatalytic performance.1-5 The resultant material systems exhibited efficient photocatalytic performance and improved power conversion efficiency in solar cells, which underpin sustainable development of solar-energy conversion application. References ： 1. Adv. Mater., 2018, doi:10.1002/adma.201705666.2. Angew. Chem, 2019, doi/10.1002/anie.2018105833. Nature Commun, 2020, (2020) 11:21294. Science, 2021, 374, 621.5. Adv. Mater., 2022, 34 (10), 2106776.

(Invited) Non-Fullerene Acceptor in Organic Solar Cells Toward Improving Performance as Indoor Light Energy Harvester

Research in organic solar cells aims to develop new materials that improve efficiency. The inception of emerging non-fullerene acceptors (NFAs) by replacing the fullerene counterpart in organic solar cells (OSCs) has pushed the bulk-heterojunction based photovoltaics to achieve efficiencies around 18% [1-6]. In order to produce efficient OSCs, it is required to have donor and acceptor materials with matching absorption bands in the Vis-NIR range, high charge-carrier mobility, and a small energy offset to minimize voltage losses. Mainly, the development of Y7 NFA molecule has improved power conversion efficiencies by pairing selected polymer donors, such as PM6 [7, 8]. Nowadays, OSCs have attracted great attention for being used as indoor light energy harvesters. The organic materials in the active layer can have tuned optical band gaps, providing an absorption spectrum that matches with emission spectra of several indoor lights, e.g., halogen lights, LED (light-emitting diodes), and FLs (fluorescent lamp), which have different emitting spectra [9, 10].The use of OSCs for indoor light harvesting applications is promising for integration into low-power indoor electronic devices from microwatts to milliwatts, such as data transfer systems, alarm systems and distributed controls. Moreover, the OSCs have the possibility to be used with power wireless sensor nodes connected to the Internet of Things. At present, LEDs are the most popular low-light level sources which can be found in offices and homes. The intensity of the light emitted by an artificial light source, per unit area of a surface is called illuminance and measured in units of lux (lx). A level 500 lx is typically recommended for office environments and 200 lx for living room environments.In this research, we have been aiming at the performance and stability over time of organic solar cells under LED illumination using fullerene and non-fullerene acceptors. We have chosen as the indoor illumination source an LED lamp with a color temperature of 3000 K and color rendering index (CRI) > 80 following the protocols ISOS [11]. The LED lamp output illuminances were varied in the range from 200 to 1500 lx. We have used PM6 as polymer donor material due to their absorption spectrum and energy band gaps well-matched to the incident LED spectrum. In order to research the improvement of the performance of OSCs under indoor illumination we have compared PC70BM fullerene acceptor with ITIC-M, Y6-O, and Y7 non-fullerene acceptors. As a result, under 1000 lx illumination we achieved PCEs from ~ 12% using Y6-O, ~ 15% using PC70BM, ~16% using Y7 up to more than 18% efficiency using ITIC-M. The study is performed including optical and electrical characterization with the purpose of understanding the behavior and the transport processes taking place in the device. In future work, we focus on the stability of the encapsulated OSCs under continuous LED illumination following the agreed stability testing protocols to study which active layer turns out to be more stable under these conditions. Acknowledgements: This work was supported by the Ministerio de Ciencia, Innovación y Universidades (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739, and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. M. Ramírez-Como acknowledge to CONAHCYT ref. BPPA-20220624083033039-2364083.

Interfacial modulation by ammonium salts in hole transport layer free CsPbBr3 solar cells with fill factor over 86 %

CsPbBr3-based perovskite solar cells (PSCs) are potential candidates for the next-generation photovoltaic technology owing to their robust stability. Nevertheless, the inorganic CsPbBr3 PSCs using carbon electrode without hole transport layer usually suffer from severe non-radiative recombination loss at CsPbBr3/Carbon interfaces, thereby generating low fill factors (FFs) and further limiting the improvement of power conversion efficiencies (PCEs). To circumvent this issue, we proposed a universal interfacial engineering strategy to reduce the trap-assisted recombination through depositing butylammonium bromide (BABr) on the surface of CsPbBr3 films, which would enhance the FF and subsequent PCE of inorganic PSCs. The experimental results illustrate that the BABr modification could not only improve the morphology and phase purity of the inorganic perovskite films, but also adjust the energy level alignment between the CsPbBr3 layer and carbon electrode. After the optimization of BABr concentrations, we fabricated the BABr-modified device delivered an impressive PCE of 9.86 % with an extreme high FF over 86 %, which is one of the highest values achieved among the reported inorganic PSCs. Moreover, the PCE of unsealed CsPbBr3 device with BABr exhibited almost no attenuation after 90 days storage under the ambient atmosphere.

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.

Exploiting Mechanism of Enhanced Charge Transfer in Ternary Organic Solar Cells at Low Energy Loss

The structural disorder and aggregation of the third acceptor with the host active layer are critical in the light absorption, film morphology, and charge‐carrier mechanism of their photovoltaic blends to achieve highly efficient organic solar cells (OSCs). However, an effective third component needs to be introduced in the host binary blend as a combination of ternary blend, which can improve the absorption profile, film morphology, and charge dynamics. In this work, non‐fullerene acceptor DRCTF is incorporated as a third component in host PM6:Y6 binary blend. Compared to host blend, the ternary blend improves charge‐transfer processes, as evidenced by steady‐state photoluminescence and time‐resolved photoluminescence measurements. It is found that the addition of 20% DRCTF into host binary blend results in improved charge dissociation and transport with reduced recombination, and voltage losses. All these characteristics contribute to an improved power conversion efficiency of 14.45% in the PM6:Y6:DRCTF ternary OSCs (T‐OSCs), compared to PM6:Y6 (12.46%) in open‐air fabrication conditions. Consequently, in this study, the impact of third components on the charge‐transfer mechanism in T‐OSCs is elucidated. These findings suggested that T‐OSCs with a perfectly chosen third component in the host binary blend achieve a comprehensive absorption profile, smooth film morphology, efficient charge dynamics, and reduced voltage loss.

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 &gt; 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