Improved Power Conversion Efficiency Research Articles

Synthesis of hydrophobic silica without traditional aging process to construct the anti-reflective film with ultralow refractive index for improving power conversion efficiency

The fabrication of anti-reflective films to optimize sunlight utilization encounters various challenges. Herein, we have synthesized modified silica with hydrophobic properties, eliminating the conventional aging process to create an anti-reflective film with an ultralow refractive index of 1.05, marking the lowest value reported to date. This innovative methodology reduces tasks that typically require days or weeks to just a few hours, thereby significantly accelerating production. The power conversion efficiency of the photovoltaic device can increase by 6.2 % when coated with this film. This research not only advances the synthesis of silica but also develops anti-reflective films with record-low refractive indices. This breakthrough represents a substantial contribution, highlighting its significant impact on the photovoltaic field.

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.

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.

Advanced Light Management for Encapsulated Silicon Solar Cells: An Antireflective Textured Film with a Down-Shifting Lead-free Perovskite Cs2AgxNa1-xBiyIn1-yCl6 Phosphor.

Light management (LM) is the key to the encapsulation of high-performance silicon (Si) photovoltaic devices (PVs). In this work, simulation analyses provide meaningful insights into optical losses and guide the improvement of the PV performance of the encapsulated silicon solar cells (Encap-Si SCs). An antireflective layer, textured polydimethylsiloxane (PDMS), is designed to reduce reflection losses, especially at a lower illumination intensity, thereby achieving an improvement of 10.89% in the short-current density (JSC) and hence 12.67% in the power conversion efficiency (PCE) when illuminated at an incident angle of 60°. Subsequently, a luminescence down-shifting material, lead-free Cs2AgxNa1-xBiyIn1-yCl6 (CANBIC) double perovskite phosphor, is incorporated into the PDMS film to further enhance the energy yield in the ultraviolet (UV) region. The textured PDMS film with an optimized CANBIC content ultimately achieves a significant improvement in PCE from 21.770 to 23.136%. This enhancement is attributed to the increase in JSC by 2.381 mA/cm2 due to the reduced reflection losses (by antireflective PDMS) and down-converted UV energy (by CANBIC), providing a remarkable advance in LM toward highly efficient encapsulated PVs.

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.

Intelligent MPPT for High Gain Zeta Converter for Standalone PV Application with Galvanic Isolation

In this paper, Standalone PV system is designed to operate without the need of electric utility grid which are commonly designed to supply specific DC electric loads. These type of PV system are generally powered using photovoltaic array and consist of solar charging modules, controllers and regulators. The objective of this work is to implement the Radial Basis Function Neural Network (RBFNN) based Maximum Power Point Tracking (MPPT) technique to attain constant DC link voltage of the ZETA converter. This method utilizes a ZETA converter to achieve better voltage gain and lower ripple in the output current and voltage. Using an Artificial Neural Network (ANN) controller to operate a high frequency converter, which improves power conversion efficiency. To ensure safety and prevent electrical faults, an isolation transformer provides galvanic isolation between the high frequency converter and the PV system. Galvanic isolation avoids electrical faults from being transmitted and safeguards connected loads. The rectifier is used to supply the Direct Current (DC) load with the output from the isolation transformer. The rectifier changes the transformer’s Alternating Current (AC) output into DC current to power DC loads. An intelligent MPPT is employed to stabilize the converter’s output voltage and address the intermittent characteristics of PV, and also assists in sustaining the DC link voltage without alterations and ripples from the converter. The efficiency of this work is authenticated via MATLAB simulation 2021a.

Highly Efficient Layer-by-Layer Organic Photovoltaics Enabled by Additive Strategy

In this work, layer-by-layer organic photovoltaics (LbL OPVs) were prepared by sequentially spin-coating PM1 and L8-BO solutions. The solvent additive 1,8-diiodooctane (DIO), which has a high boiling point, and solid additive l,3,5-trichlorobenzene (TCB), which has a high volatile, were deliberately selected to incorporate with the L8-BO solutions. The power conversion efficiency (PCE) of LbL OPVs was considerably enhanced from 17.43% to 18.50% by employing TCB as the additive, profiting by the concurrently increased short-circuit current density (JSC) of 26.74 mA cm−2 and a fill factor (FF) of 76.88%. The increased JSCs of LbL OPVs with TCB as additive were ascribed to the tilted-up absorption edge in the long wavelength range and the external quantum-efficiency spectral difference between LbL OPVs with and without TCB as an additive. The molecular arrangement of L8-BO and the PM1 domain was enhanced with TCB as an additive, which was most likely responsible for the increased charge mobilities in the layered films processed with additives. It was indicated that the dynamic film-forming process of the acceptor layers plays a vital role in achieving efficient LbL OPVs by employing additive strategy. Over 6% PCE improvement of the LbL OPVs with PM1/L8-BO as the active layers can be achieved by employing TCB as additive.

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.

Optimizing charge transport and band-offset in silicon heterojunction solar cells: impact of TiO2 contact deposition temperature

Carrier selective contacts are a primary requirement for fabricating silicon heterojunction solar cells (SHSCs). TiO2 is a prominent carrier selective contact in SHSCs owing to its excellent optoelectronic features such as suitable band offset, work function, and cost-effectiveness. Herein, we fabricated simple SHSCs in an Al/TiO2/p-Si/Ti/Au device configuration. Ultrathin 3 nm TiO2 layers were deposited onto a p-type silicon substrate using the atomic layer deposition method. The deposition temperature of TiO2 layers varied from 100 °C to 250 °C. X-ray photoelectron spectroscopic studies suggest that deposition temperature highly affects the chemical states of TiO2 and reduces the formation of defective state densities at the Fermi energy. The optical band gap values of TiO2 layers are also altered from 3.13 eV to 3.27 eV when the deposition temperature increases. The work function tuning from −5.13 eV to −4.83 eV has also been observed in TiO2 layers, suggesting the variation in Fermi level tuning, which arises due to changes in carrier concentrations at higher temperatures. Several device parameters, such as ideality factor, trap density, reverse saturation current density, barrier height, etc, have been quantified to comprehend the effects of deposition temperature on photovoltaic device performance. The results suggest that the deposition temperature significantly influences the charge transport and device performance. At an optimum temperature, a significant reduction in charge carrier recombination and trap state density has been observed, which helps to improve power conversion efficiency.

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.

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.

Indoor Light Harvesting Perovskite Solar Cells on Conducting Oxide-Free Ultrathin Deformable Substrates.

Perovskite solar cells (PSCs) are receiving renewed interest since they have reached high power conversion efficiency (PCE) and show potential for application not only on rigid and flexible substrates but also on mechanically deformable substrates for integration on nonplanar curvilinear surfaces. Here we demonstrate PSCs fabricated on transparent conducting oxide-free ultrathin polyethylene terephthalate substrates capable of efficiently harvesting indoor light even under compressive strain. Interface engineering with poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) improved the shunt resistance and band alignment at the perovskite-hole transport layer interface, which resulted in enhanced charge extraction, leading to 114% improvement in PCE from 5.57 to 11.91% under 500 lx indoor white LED (4000 K) illumination. The champion device exhibited a PCE of 18.37% under 250 lx cool white LED (4000 K) light. The maximum power output (P max) of the devices varied from 13.78 to 25.38 μW/cm2 by changing the indoor light illumination from 250 to 1000 lx, respectively. Moreover, the devices showed impressive performance even after mechanical deformation and retained 83 and 76% for 1 sun and indoor light, respectively, under 30% compressive strain. Our approach paves the way for fabrication of efficient indoor light harvesting PSCs on mechanically deformable substrates for integration on nonplanar surfaces prone to compressive strain.

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.

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 °C). 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 650 °C. The effect of CdS and CdS:O/CdS layers on the microstructural and morphological features of CdCl2-treated CdTe films were critically analyzed in 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.

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