Xiaoyan Du

Shandong University | SDU · School of Physics

We use an automated research platform combined with machine learning to assess and understand the resilience against air and light during production of organic photovoltaic (OPV) devices from over 40 donor and acceptor combinations. The standardized protocol and high reproducibility of the platform results in a dataset of high variety and veracity...

Ultra-flexible and stretchable organic photodetectors (s-OPDs) sensitive in the near-infrared (NIR) region hold great potential for wearable health monitoring with excellent physiological signal and skin conformability. However, the development of OPDs that combines NIR sensitivity, low power consumption, low cost, simple fabrication structure, and...

In recent years, the emergence of high‐efficiency non‐fullerene acceptors (NFAs) has pushed the power conversion efficiency (PCE) beyond 19% in organic solar cells (OSCs). For solution processing of the photoactive layers, the study of solvent properties on device performance has become a hot research topic towards up‐scaling. Here, we reveal the k...

Developing efficient organic solar cells (OSCs) with thick active layers is crucial for roll‐to‐roll printing. However, thicker layers often result in lower efficiency. This study tackles this challenge using a polymer adsorption strategy combined with a layer‐by‐layer approach. Incorporating insulator polystyrene (PS) into the PM6:L8‐BO system cre...

The layer‐by‐layer (LbL) organic photovoltaics (OPVs) are constructed with wide‐bandgap donor PM1 and narrow‐bandgap acceptor L8‐BO. The exciton utilization near cathode is still challenging considering restricted diffusion distance of excitons and inability for transferring energy from L8‐BO to PM1. Herein, donor incorporation into acceptor layer...

By introducing highly crystalline material D18A into donor layer acting as energy donor and nucleating agent, an optimal PCE of 19.25% was achieved for PM1 : D18A/L8-BO based OPVs.

Organic photodetectors (OPDs) are a potential next-generation photodetection technology because they are lightweight, flexible, and have customizable spectral responses. However, high dark currents with low detectability remain major challenges, limiting the widespread application of photomultiplication OPDs (PM-OPDs). This work describes a straigh...

With the rapid increase in power conversion efficiency of organic photovoltaics due to the development of non‐fullerene acceptors (NFAs), prolonging the operational lifetime of devices becomes one of the critical prerequisites for commercial application. In this work, the degradation pathways of a wide range of state‐of‐the‐art NFA molecules via mu...

Structural defects in organic solar cells (OSCs) can significantly impact their performance by altering the density of the trap states and disrupting the energy-level alignment. These defects are primarily formed during the film-formation process, serving as intrinsic traps. In this study, we employed a dilution approach by blending an insulating p...

The operational stability of high-performance organic solar cells (OSCs) based on Y-series small-molecule acceptors is hindered by strong photocarrier trapping processes as governed by thermodynamic relaxation in the mixed morphological domains. Herein, the signature of photocarrier trapping associated with exciton-phonon coupling is identified by...

Benefiting from the synergistic development of material design, device engineering, and the mechanistic understanding of device physics, the certified power conversion efficiencies (PCEs) of single‐junction non‐fullerene organic solar cells (OSCs) have already reached a very high value of exceeding 19%. However, in addition to PCEs, the poor stabil...

Organic solar cells (OSCs) now approach power conversion efficiencies of 20%. However, in order to enter mass markets, problems in upscaling and operational lifetime have to be solved, both concerning the connection between processing conditions and active layer morphology. Morphological studies supporting the development of structure–process–prope...

Metal halide perovskite single crystals are promising for diverse optoelectronic applications due to their outstanding properties. In comparison to the bulk, the crystal surface suffers from high defect density and is moisture sensitive; however, surface modification strategies of perovskite single crystals are relatively deficient. Herein, solar c...

The investigation of drying dynamics and kinetic quenching depth related degradation of high‐performance photoactive materials with scalable coating techniques demands significant research attention. Herein, film formation kinetics regulated crystallinity, preferential orientation and vertical phase separation of the active layers is revealed, whic...

The current power conversion efficiencies of laboratory‐sized organic solar cells (OSCs), based on the spin‐coating process with halogenated solvents, have exceeded 19%. Environmentally friendly printing is needed to bridge the gap between laboratory and industrialization by being compatible with roll‐to‐roll large‐area production. Here, the molecu...

After fast developing of single-junction perovskite solar cells and organic solar cells in the past 10 years, it is becoming harder and harder to improve their power conversion efficiencies. Tandem solar cells are receiving more and more attention because they have much higher theoretical efficiency than single-junction solar cells. Good device per...

Voltage losses are one of the main obstacles for further improvement in the power conversion efficiency of organic solar cells. In this work, we investigate the effect of thermal stress on voltage losses in various material systems by multiple spectroscopic measurements on both devices and thin films. The energetics of nonfullerene small molecules...

A method for organic solar cell (OSC) stability testing is presented that aims to provide more unique insight into the causes of degradation patterns of OSCs. The method involves using monochromatic light at high irradiation doses to accelerate isolated degradation mechanisms while monitoring the device with a series of in‐situ steady‐state and tra...

An unfavorable energy landscape can create intra-bandgap tail states, induce extra energy loss and enhance photocarrier trapping, thereby limiting both the performance and stability of non-fullerene organic solar cells (OSCs). Herein, a favorable energy landscape picture at the device level is conceived by a synergistic approach of interface modifi...

All-polymer solar cells with bulk-heterojunction films composed of polymeric donors and acceptors are distinguished for their outstanding device stability. However, unfavorable thermodynamic mixing of polymers induced severe phase-separated morphology related to electron–phonon coupling, limiting the practical development of high-efficiency organic...

With the rise of Internet of Things, indoor organic photovoltaic (IOPV) devices as the promising power supply unit of off-grid electronics have made great progress in recent years. However, as the only acceptable end-goal, their commercial large-scale production is still a long way off although the absolute efficiency values achieve significant bre...

Stability is one of the most important challenges facing material research for organic solar cells (OSC) on their path to further commercialization. In the high-performance material system PM6:Y6 studied here, we investigate degradation mechanisms of inverted photovoltaic devices. We have identified two distinct degradation pathways: one requires t...

The power conversion efficiency (PCE) for small-area lab-produced single-junction OSCs reaches ~19% with an active area normally below 0.1 cm2. When scaling up lab cells to large-area modules, the photovoltaic performance generally drops. Here, we highlight the representative high-performance devices and modules with active area over 1 cm2, concern...

Stability is one of the most important challenges facing organic solar cells (OSC) on their path to commercialization. In the high-performance material system PM6:Y6 studied here, investigate degradation mechanisms of inverted photovoltaic devices. We have identified two distinct degradation pathways: one requires presence of both illumination and...

Organic Solar Cells In article number 2103371, Xiao‐Yan Du, Xiao‐Tao Hao and co‐workers rationalize the underlying correlation mechanisms between intermolecular electron‐phonon coupling and trapping of electronic excitation behind the kinetic aggregation behaviors of BTP‐eC9 in bulk‐heterojunction and layer‐by‐layer processed multicomponent organic...

The development of organic photovoltaic (OPV) technologies has reached a respective scientific level of understanding. The power conversion efficiency (PCE) of >18% has been demonstrated for lab‐scale organic solar cells (OSCs), while large‐scale organic solar modules (>200 cm 2 ) have achieved PCEs close to 12%. In order to continuously develop th...

The kinetic aggregation of nonfullerene acceptors under nonequilibrium conditions can induce electron–phonon interaction roll‐off and electronic band structure transition, which represents an important limitation for long‐term operational stability of organic solar cells (OSCs). However, the fundamental underlying mechanisms have received limited a...

Lead–tin (Pb/Sn) mixed perovskites are considered as promising photovoltaic materials owing to their adjustable bandgap and excellent optoelectronic properties. The low-bandgap perovskite solar cells (PSCs) based on lead–tin mixed perovskites play a critical role in the overall performance of perovskite-based tandem devices. Nevertheless, the curre...

Simultaneously enhancing device performance and longevity, as well as balancing the requirements on cost, scalability, and simplification of processing, is the goal of interface engineering of organic solar cells (OSCs). In our work, we strategically introduce antimony (Sb³⁺) cations into an efficient and generic n-type SnO2 nanoparticles (NPs) hos...

The development of complex functional materials poses a multi-objective optimization problem in a large multi-dimensional parameter space. Solving it requires reproducible, user-independent laboratory work and intelligent preselection of experiments. However, experimental materials science is a field where manual routines are still predominant, alt...

The power conversion efficiency (PCE) for single-junction OSCs (SJ-OSCs) has exceeded 18%. Further increasing the PCE is demanded in order to make this photovoltaic technology commercially attractive. Theoretically, tandem organic solar cells (T-OSCs) can achieve a higher PCE than the state-of-the-art SJ-OSCs. Recently, a record PCE of 18.7% has be...

The development of complex functional materials poses a multi-objective optimization problem in a large multidimensional parameter space. Solving it requires reproducible, user independent laboratory work and intelligent preselection of experiments. However, experimental materials science is a field where manual routines are still predominant, alth...

Stability of perovskite-based photovoltaics remains a topic requiring further attention. Cation engineering influences perovskite stability, with the present-day understanding of the impact of cations based on accelerated ageing tests at higher-than-operating temperatures (e.g. 140°C). By coupling high-throughput experimentation with machine learni...

Evaluating the potential of organic photovoltaic (OPV) materials and devices for industrial production is a multidimensional optimization process with an incredibly large parameter space. Here, we demonstrate automated OPV material and device characterization in terms of efficiency and photostability. Gaussian process regression (GPR) prediction ba...

We investigate the photovoltaic characteristics of organic solar cells (OSCs) for two distinctly different nanostructures, by comparing the charge carrier dynamics for bilayer- and bulk-heterojunction OSCs. Most interestingly, both architectures exhibit fairly similar power conversion efficiencies (PCEs), reflecting a comparable critical domain siz...

In non-fullerene organic solar cells, the long-range structure ordering induced by end-group π–π stacking of fused-ring non-fullerene acceptors is considered as the critical factor in realizing efficient charge transport and high power conversion efficiency. Here, we demonstrate that side-chain engineering of non-fullerene acceptors could drive the...

With the rise of the solar power century, photovoltaic applications and installations will go beyond the traditional green field power plants and enter any aspect of daily life. Organic photovoltaics (OPVs) demonstrate certified cell efficiencies of over 17% and are expected to contribute to versatile applications powered by solar energy, for insta...

The performance and industrial viability of organic photovoltaics are strongly influenced by the functionality and stability of the interface layers. In article number 2002973, Na Li, Ning Li, Xinghua Wang, Li Nian, and co‐workers present an advanced aqueous solution‐processed cathode interface layer based on cost‐effective organosilica nanodots (O...

The performance and industrial viability of organic photovoltaics are strongly influenced by the functionality and stability of interface layers. Many of the interface materials most commonly used in the lab are limited in their operational stability or their materials cost and are frequently not transferred toward large‐scale production and indust...

A major challenge for organic solar cell (OSC) research is how to minimize the tradeoff between voltage loss and charge generation. In early 2019, we reported a non-fullerene acceptor (named Y6) that can simultaneously achieve high external quantum efficiency and low voltage loss for OSC. Here, we use a combination of experimental and theoretical m...

In non-fullerene organic solar cells (OSCs), the long-range structure ordering induced by end group π–π stacking of fused-ring non-fullerene acceptors is considered as the critical factor in realizing efficient charge transport and high power conversion efficiency. Here, we demonstrate that side-chain engineering of non-fullerene acceptors could dr...

Potentiostatic impedance spectroscopy (IS) is a well-established characterization technique for elucidating the electric resistivity and capacitive features of materials and devices. For solar cells, by applying a small voltage perturbation the current signal is recorded and the recombination processes and defect distributions can be accessed. In t...

Two pairs of constitutional isomers of fused-octacyclic nonfullerene acceptors (NFAs) based on a naphthalene-bisthienothiophene core with or without fluorination at the ending groups have been developed. Compared with the axisymmetric NFAs N66-IC and N66-2FIC with two six-member-ring bridges, their asymmetric constitutional isomers N65-IC and N65-2...

Solution processed bilayer organic solar cells (OSCs) with high performance are demonstrated for non-fullerene small molecular acceptors (NFAs). Unlike fullerene acceptors, NFAs show significant spectral overlap between their absorption and the photoluminescence (PL) of a polymer donor, which makes the design of efficiently exciton harvesting bilay...

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new mater...

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new mater...

Great attention has been paid on developing low bandgap non-fullerene acceptors (NFAs) for matching wide bandgap donor polymers to increase the photocurrent and therefore the power conversion efficiencies (PCEs) of NFA organic solar cells. While most of the pyrene-core based acceptor-donor-acceptor (A-D-A) NFAs have been structurally limited to its...

As the power conversion efficiency (PCE) of organic solar cells (OSCs) has surpassed the 17% baseline, the long-term stability of highly efficient OSCs is essential for the practical application of this photovoltaic technology. Here, the photostability and possible degradation mechanisms of three state-of-the-art polymer donors with a commonly used...

The performance of tandem organic solar cells (OSCs) is directly related to the functionality and reliability of the interconnecting layer (ICL). However, it is a challenge to develop a fully functional ICL for reliable and reproducible fabrication of solution‐processed tandem OSCs with minimized optical and electrical losses, in particular for bei...

Potentiostatic impedance spectroscopy (IS) is a well stablished characterization technique for elucidating the electric resistivity and capacitive features of materials and devices. In the case of solar cells, by applying a small voltage perturbation the current signal is recorded and the recombination processes and defect distributions are among t...

With state‐of‐the‐art organic solar cells (OSCs) surpassing 16% efficiency, stability becomes critical for commercialization. In this work, the power of using photoluminescence (PL) measurements on plain films is demonstrated, as well as high‐performance liquid chromatography analysis to reveal the origin of UV instabilities in OSCs based on the mo...

Worldwide research efforts have been devoted to organic photovoltaics in hope of large-scale commercial application in the near future. To meet the industrial production requirements, organic photovoltaics that can reach power conversion efficiency (PCE) over 10% along with promising operational device stability are of utmost interest. In the study...

Solution‐processed organic solar cells (OSCs) are promising low‐cost, flexible, portable renewable sources for future energy supply. The state‐of‐the‐art OSCs are typically fabricated from a bulk‐heterojunction (BHJ) active layer containing well‐mixed donor and acceptor molecules in the nanometer regime. However, BHJ solar cells suffer from stabili...

The performance of organic photovoltaics is largely dependent on the balance of short-circuit current density (JSC) and open-circuit voltage (VOC). For instance, the reduction of the active materials’ optical bandgap, which increases the JSC, would inevitably lead to a concomitant reduction in VOC. Here, we demonstrate that careful tuning of the ch...

Organic solar cells (OSCs) based on non-fullerene acceptors (NFAs) have developed very fast in recent years. A proper balance among power conversion efficiency (PCE), stability, and production cost needs further elaboration. Here we investigate the industrial viability of highly efficient OSCs based on several representative NFAs. The most stable O...

In-operando soft X-ray microspectroscopy of organic electronics devices - Volume 24 Supplement - Rainer H. Fink, Benedikt Rosner, Xiaoyan Du, Andreas Spam, Manuel Johnson, Tim Hawly, Benjamin Watts, Jorg Raabe, Luca Gregoratti, Matteo Amati

One of the most important factors that limits the efficiencies of bulk‐heterojunction organic solar cells (OSCs) is the modest open‐circuit voltage (Voc) due to their large voltage loss (Vloss) caused by significant nonradiative recombination loss. To boost the performance of OSCs toward their theoretical limit, developing high‐performance donor: a...

We report two novel small-molecule non-fullerene acceptors, IF-TN and IDT-TN, with indenofluorene (IF) and indacenodithiophene (IDT) as their respective central electron-rich cores and naphthyl-fused indanone (N) as the electron-withdrawing end-groups. By pairing these non-fullerene acceptors with a widely used polymer PBDB-T, the fabricated polyme...

A major bottleneck delaying the further commercialization of thin-film solar cells based on hybrid organohalide lead perovskites is interface loss in state-of-the-art devices. We present a generic interface architecture that combines solution-processed, reliable, and cost-efficient hole-transporting materials without compromising efficiency, stabil...

The booming of hybrid organohalide lead perovskites in the past few years attracted the broad interest in photovoltaics (PVs) and other optoelectronics research community. [1–7] This is not only because of its unprecedented rate of development compared Thin-film solar cell based on hybrid perovskites shows excellent light-to-power conversion effici...

Organic solar cells based on multinary components are promising to further boost the device performance. The complex interplay of the morphology and functionality needs further investigations. Here, we report on a systematic study on the morphology evolution of prototype ternary systems upon adding sensitizers featuring similar chemical structures...

Organic solar cells are promising in terms of full-solution-processing which enables low-cost and large-scale fabrication. While single-junction solar cells have seen a boost in power conversion efficiency (PCE), multi-junction solar cells are promising to further enhance the PCE. In all-solution-processed multi-junction solar cells, interfacial lo...

One of the most employed morphology optimization methods to design better performing organic photovoltaic devices is ink formulation engineering with additives. In this work, by employing a suboptimal host solvent mixture and 1,8-diiodooctane (DIO) as a very optimal solvent for both components in poly-thieno[3,2b]thiophene-diketopyrrolopyrrole-co-t...

A dumbbell-like A-D-A molecule, triad , containing a dithienosilole-dibenzothiadiazole donor unit and two fullerene acceptor units was designed and synthesized. Triad shows good solubility, thermostability, light absorbance, and film-forming capability. Solar cells using as the active layer gave a PCE of 0.4%.

Selective preparation of C60(CH2)n (n = 1, 2, 3) was realized via a "Bingel-decarboxylation" route. A 54π-electron derivative of C60(CH2)2, OQBMF, demonstrates an outstanding power conversion efficiency (PCE) of 6.43% (Voc = 0.95 V, Jsc = 9.67 mA cm(-2), FF = 70%) in fullerene:P3HT solar cells since the small CH2 addends lift up fullerene LUMO and...

A D-A conjugated polymer (PThTPTI) was developed by using a brand new pentacyclic aromatic lactam acceptor unit (TPTI). PThTPTI possesses good light absorption, thermal stability, and a deep HOMO level. PThTPTI/PC71BM cells afford an outstanding PCE up to 7.80%, with high Voc (0.87 V), Jsc (13.69 mA cm−2) and FF (65.6%), and over 70% EQE in the ran...

Two electron-deficient tetracyclic monomers, 6,9-dibromo-7,8-bis(octyloxy)-11H-indeno[2,1-b] quinoxalin-11-one (M1) and 1,3-bis(5-bromo-4-hexylthiophen-2-yl)-9H-indeno[1,2-b]thieno[3,4-e]pyrazin-9-one (M2), are synthesized through condensation of ninhydrin with aromatic diamines in good yields. Copolymerization of M1 with thiophene (Th) and dithien...

A new class of thermo-cleavable fullerenes, di-tert-butyl methano[60]fullerene-61,61-dicarboxylate (DBMD), bis(2-methylhexan-2-yl) methano[60]fullerene-61,61-dicarboxylate (BMHMD), and di-tert-butyl methano[60]fullerene-61,61-dicarboxylate bis-adducts (bis-DBMD), was facilely prepared through one-step Bingel reaction from C60. At high temperature,...

Stabilizing the optimal film morphology of bulk heterojunction polymer solar cells is key for realizing long-term stable devices. A crosslinker, octane-1,8-diyl bis(1,4-dihydrobenzo[d][1,2]oxathiine-6-carboxylate 3-oxide) (OBOCO), was designed to crosslink PC61BM through a heat-triggered Diels–Alder reaction to suppress the aggregation tendency of...

Inverted polymer solar cells with a configuration of ITO/ZnO/PBDTTT-C:PC71BM/MoO3/Ag were fabricated and a power conversion efficiency of 6.64% was achieved under AM 1.5G irradiation (89 mW/cm2). The function of UV light was systematically investigated by tracking the changes of the device performance for 212 min under continuous illumination with...

Three new low bandgap donor–acceptor–donor (D–A–D) type small molecules (M1–M3) containing naphthalene, thiophene, and diketopyrrolopyrrole were synthesized by Suzuki and Stille coupling reactions. The thermal, optical, electrochemical and photovoltaic properties of these molecules were investigated. These materials possess strong absorption at 475...

Seven new conjugated D-A copolymers (P1 - P7 ) containing a strong electron deficient pyromellitic diimide (PMDI) unit and a donor unit such as thiophene, bithiophene, benzo [ 1, 2-b; 3,4-b'] dithiophene,and dithieno[3, 2-b: 2', 3'-d] silole were synthesized by the Stille coupling reaction. P1 - P7 possess good solubility in common organic solvents...

N-alkylaziridino[60]fullerenes (NAAFs) were synthesized through the reaction of C60 and primary alkylamines with the aid of di(acetoxyiodo)benzene (DIB) and I2 under mild conditions. The NAAFs exhibit similar LUMO energy levels (−3.82 eV to −3.89 eV), which is comparable with PC61BM. The NAAFs are thermally stable with the decomposition temperature...