Yuanping Yi

Chinese Academy of Sciences | CAS · Institute of Chemistry

Exciton binding energy (Eb) is a key parameter to determine the mechanism and performance of organic optoelectronic devices. Small Eb benefits to reduce the interfacial energy offset and the energy loss of organic solar cells. However, quantum‐chemical calculations of the Eb in solid state with considering electronic polarization effects are extrem...

State-of-the-art organic photovoltaic (OPV) devices are based on Y6-acceptors, with power conversion efficiencies now exceeding 20%. However, the basic structure-photophysics-performance relationship of these materials remains unclear, hindering rational material development...

Exciton binding energy (Eb) is a key parameter to determine the mechanism and performance of organic optoelectronic devices. Small Eb benefits to reduce the interfacial energy offset and the energy loss of organic solar cells. However, quantum‐chemical calculations of the Eb in solid state with considering electronic polarization effects are extrem...

Molecular doping is essential to improve the electrical conductivity of organic semiconductors for high-performance organic electronic devices. However, the doping efficiency is influenced by several factors, such as the energy levels, energetic fluctuations, dielectric properties, and molecular packing structures of the doped films, and the underl...

Organic donor‐acceptor (D‐A) conjugated macrocycles, which are regarded as terminal‐less counterparts of linear π‐systems, have emerged as a promising class material for organic optoelectronics. Nevertheless, circular symmetry generally makes the lowest electronic transition symmetry forbidden, which is a huge obstacle to developing bright near‐inf...

For organic solar cells (OSCs), bridging the gap with Shockley–Queisser limit necessitates simultaneously reducing the energy loss for a high open-circuit voltage, improving light utilization for enhanced short-circuit current density and maintaining ideal nanomorphology with a high fill factor through molecular design and device engineering. Here...

Outstanding charge transport in molecular crystals is of great importance in modern electronics and optoelectronics. The widely adopted strategies to enhance charge transport, such as restraining intermolecular vibration, are mostly limited to organic molecules, which are nearly inoperative in 2D inorganic molecular crystals currently. In this cont...

The energetic landscape of charge carriers, namely the ionization potential (IP) and electron affinity (EA), can play a crucial role in the charge separation and migration processes for organic solar...

Giant molecular acceptors (GMAs) are typically designed through the conjugated linking of individual small molecule acceptors (SMAs). This design imparts an extended molecular size, elevating the glass transition temperature (Tg) relative to their SMA counterparts. Consequently, it effectively suppresses the thermodynamic relaxation of the acceptor...

Controlling triplet states is crucial to improve the efficiency and lifetime of organic room temperature phosphorescence (ORTP). Although the intrinsic factors from intramolecular radiative and non-radiative decay have been intensively investigated, the extrinsic factors that affect triplet exciton quenching are rarely reported. Diffusion to the de...

Polymer solar cells (PSCs) rely on a blend of small molecular acceptors (SMAs) with polymer donors, where thermodynamic relaxation of SMAs poses critical concerns on operational stability. To tackle this issue, tethered SMAs, wherein multiple SMA‐subunits are connected to the aromatic‐core via flexible chains, are proposed. This design aims to an e...

Giant molecular acceptors (GMAs) are typically designed through the conjugated linking of individual small molecule acceptors (SMAs). This design imparts an extended molecular size, elevating the glass transition temperature (Tg) relative to their SMA counterparts. Consequently, it effectively suppresses the thermodynamic relaxation of the acceptor...

Polymer solar cells (PSCs) rely on a blend of small molecular acceptors (SMAs) with polymer donors, where thermodynamic relaxation of SMAs poses critical concerns on operational stability. To tackle this issue, tethered SMAs, wherein multiple SMA‐subunits are connected to the aromatic‐core via flexible chains, are proposed. This design aims to an e...

Polymerization of Y6-type acceptor molecules leads to bulk-heterojunction organic solar cells with both high power-conversion efficiency and device stability, but the underlying mechanism remains unclear. Here we show that the exciton recombination dynamics of polymerized Y6-type acceptors (Y6-PAs) strongly depends on the degree of aggregation. Whi...

A supramolecular binary doping metal-free graphdiyne is achieved via controllable N–H⋯F hydrogen bonds between trifluoro-graphdiyne skeleton and guest molecules. The as-prepared zinc-air battery exhibits high cycling stability and specific capacity.

Organic cocrystals attract wide research interest due to their unique properties. However, the development of crystal engineering is relatively slow because of the difficulty in the design of molecular structures...

Compared to inorganic and perovskite counterparts, organic solar cells (OSCs) suffer from much severer nonradiative energy loss due to the nongeminate recombination via triplet states at the donor:acceptor interfaces. To...

A new n-type dopant featuring a pyrene unit was developed, which shows better charge-generation efficiency for a naphthalene diimide (NDI)-based conjugated polymer than N-DMBI due to the distinctive interaction between the pyrene and the NDI units.

The blend nanomorphology of electron‐donor (D) and ‐acceptor (A) materials is of vital importance to achieving highly efficient organic solar cells. Exogenous additives especially aromatic additives are always needed to further optimize the nanomorphology of blend films, which is hardly compatible with industrial manufacture. Herein, we proposed a...

The blend nanomorphology of electron‐donor (D) and ‐acceptor (A) materials is of vital importance to achieving highly efficient organic solar cells (OSCs). Exogenous additives especially aromatic additives are always needed to further optimize the nanomorphology of blend films, which is hardly compatible with industrial manufacture. Herein, we prop...

The synthesis of anisotropic colloidal building blocks is essential for their self‐assembly into hierarchical materials. Here, a highly efficient stabilizer‐assisted liquid‐crystallization‐driven self‐assembly (SA‐LCDSA) strategy was developed to achieve monodisperse colloidal polymer rods. This strategy does not require the use of block copolymers...

The synthesis of anisotropic colloidal building blocks is essential for their self‐assembly into hierarchical materials. Here, a highly efficient stabilizer‐assisted liquid‐crystallization‐driven self‐assembly (SA‐LCDSA) strategy was developed to achieve monodisperse colloidal polymer rods. This strategy does not require the use of block copolymers...

The nonradiative energy loss (∆Enr) is a critical factor to limit the efficiency of organic solar cells. Generally, strong electron-phonon coupling induced by molecular motion generates fast nonradiative decay and causes high ∆Enr. How to restrict molecular motion and achieve a low ∆Enr is a sticking point. Herein, the free volume ratio (FVR) is pr...

A simple strategy to simultaneously achieve fast reverse intersystem crossing (RISC) and low non‐radiative decay rates in thermally activated delayed fluorescence (TADF) emitters is still lacking. Here, the green TADF emitters containing aromatic ketones and prepared D‐Ph and D‐PhCz containing different amounts of deuterium are deuterated to study...

Non‐benzenoid polycyclic aromatic hydrocarbons (PAHs) have received a lot of attention because of their unique optical, electronic, and magnetic properties, but their synthesis remains challenging. Herein, we report a non‐benzenoid isomer of peri‐tetracene, diazulenorubicene (DAR), with two sets of 5/7/5 membered rings synthesized by a (3+2) annula...

Non‐benzenoid polycyclic aromatic hydrocarbons (PAHs) have received a lot of attention because of their unique optical, electronic, and magnetic properties, but their synthesis remains challenging. Herein, we report a non‐benzenoid isomer of peri ‐tetracene, diazulenorubicene (DAR), with two sets of 5/7/5 membered rings synthesized by a (3+2) annul...

Hybrid metal halides (HMHs) are a class of materials that combine extraordinary photophysical properties and excellent processability. Their chemical variability allows for the solid-liquid transition toward melt-processable HMHs. Herein, we report the design and synthesis of zero-dimensional HMHs [M(DMSO)6][SbCl6], where the isolated octahedra of...

Precise control of molecular assembly is of great significance in the application of functional molecules. This work has systematically investigated the humidity effect in bubble‐assisted molecular assembly. This work finds humidity is critical in the evolution of the soft confined space, leading to the formation of microscale liquid confined space...

High carrier mobility is beneficial to increase the active-layer thickness while maintaining a high fill factor, which is crucial to further improve the light harvesting and organic photovoltaic efficiency. The aim of this Perspective is to elucidate the electron transport mechanisms in prototypical non-fullerene (NF) acceptors through our recent t...

Though urgently needed, high‐efficiency near‐infrared (NIR) organic light‐emitting diode (OLED) is still rare due to the energy‐gap law. Formation of intermolecular charge‐transfer aggregates (CTA) with nonadiabatic coupling suppression can decelerate non‐radiative decay rates for high‐efficiency NIR‐OLEDs. However, the aggregation effect of CTA is...

Emissive organic semiconductors are highly demanding for organic light-emitting transistors (OLETs) and electrically pumped organic lasers (EPOLs). However, it remains a great challenge to obtain organic semiconductors with high carrier mobility and high photoluminescence quantum yield simultaneously. Here, a new design strategy is reported for hig...

A NIR strong absorbing molecule was constructed by taking the structural advantages of a quinoid and diketopyrrolopyrrole, with an absorption maximum of up to 1039 nm and hole and electron mobilities up to 0.19 and 0.2 cm ² V ⁻¹ s ⁻¹ , respectively.

A series of novel asymmetric anthracene derivatives, namely 5-BTA, 5-BTVA, and 5-BTEA, consisting of a single bond, vinyl, and ethynyl bridged benzothiophene and anthracene core were synthesized. Single crystal structure...

The impact of the connection modes between donor (D) and acceptor (A) on the luminescence properties is revealed for organic D‐A‐D emitters based on triphenylamine (TPA) and 9,10‐phenanthroquinone (PAQ). When TPA and PAQ are linked via a single bond, the emitters exhibit small energy difference between the lowest singlet and triplet excited states...

Low energy loss is a prerequisite for organic solar cells to achieve high photovoltaic efficiency. Electron-vibration coupling (i.e., intramolecular reorganization energy) plays a crucial role in the photoelectrical conversion and energy loss processes. In this concept article, we summarize our recent theoretical advances on revealing the energy lo...

Reducing the exciton binding energy Eb of organic photoactive materials is critical to minimize the energy loss and improve the photovoltaic efficiency of organic solar cells. However, the relation between the Eb and molecular packing is not well understood. Herein, the Eb in the crystals of a series of A-D-A type nonfullerene acceptors with differ...

Double‐cable polymers (DCPs) with donor and acceptor in the same molecular matrix exhibit excellent stability and have great potential in the practical application of organic solar cells (OSCs). However, such chemical structures of DCPs make the morphology and charge transport very complicated. Here, the packing structures and charge transport chan...

In contrast to the inorganic and perovskite solar cells, organic photovoltaics (OPV) depend on a series of charge generation and recombination processes, which complicates molecular design to improve the power conversion efficiencies (PCEs). Herein, we first propose the singlet‐triplet energy gap (ΔEST) as a critical molecular descriptor for predic...

Utilization of chlorinated end groups is an efficient strategy for developing small molecule nonfullerene acceptors (NFAs) with narrow bandgaps. Previous studies on nonfullerene acceptors with chlorinated end groups mainly focus on the modulation of either heterohalogenated or monochlorinated end groups, and the structure-property relationships in...

In contrast to the inorganic and perovskite solar cells, organic photovoltaics (OPV) depend on a series of charge generation and recombination processes, which complicates molecular design to improve the power conversion efficiencies (PCEs). Herein, we first propose the singlet–triplet energy gap (ΔEST) as a critical molecular descriptor for predic...

Energy loss caused by exciton binding energy (Eb) has become a key factor that restricts further advancement of organic solar cells (OSCs). Herein, we used transient mid-IR spectroscopy to study direct photogeneration of free charge carriers in small-molecule acceptors (SMAs) Y6 and IDIC as well as polymerized SMAs (PSMAs) PYFT and PZ1. We found th...

Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to some OSCs conditionally, seriously limiting their general applications. Herein, a novel p‐doping mechanism is revealed by investigating the inter...

Operation of temperature sensors over extended temperature ranges, and particularly in extreme conditions, poses challenges with both the mechanical integrity of the sensing material and the operational range of the sensor. With an emissive bendable organic crystalline material, here we propose that organic crystals can be used as mechanically robu...

The development of organic thermosensitive fluorophores for use in heat‐resistant organic light emitting diodes (OLEDs) and large‐area and flexible high‐temperature sensing remains challenging due to the susceptibility of such materials to thermally facilitated nonradiative decay. A series of “hot exciton” materials (“C1” and “C2”) based on pyrrole...

The current research investigates the structure features and intermolecular interactions of nonfullerene acceptors (NFAs) in single crystal and thin films, as well as their solar cell applications. Guiding parameters and key intermolecular forces that lead to 2D brickwork or 3D web packing are identified. The atomic modification is shown as the key...

The A‐DA′D‐A fused‐ring electron acceptors with an angular fusion mode and electron‐deficient core has significantly boosted organic photovoltaic efficiency. Here, the intrinsic role of the peculiar structure is revealed by comparing representative A‐DA′D‐A acceptor Y6 with its A‐D‐A counterparts having different fusion modes. Owing to the more del...

Designing ultra‐strong near‐infrared (NIR) absorbing organic semiconductors is the critical prerequisite for sensitive NIR thin film organic photodetectors (OPDs), especially in the region of beyond 900 nm, where the absorption coefficient of commercial single crystalline silicon (c‐Si) is below 103 cm–1. Herein, we developed a pyrrolo[3,2‐b]thieno...

The A‐DA’D‐A fused‐ring electron acceptors featuring an angular fusion mode and electron‐deficient core has significantly boosted the progress of organic solar cells. Herein, to reveal the intrinsic role of the peculiar A‐DA’D‐A structure, we have investigated the optoelectronic and excited state dynamics properties of a representative A‐DA’D‐A acc...

Rare studies of cocrystal engineering have focused on improving carrier mobility of organic semiconductors mainly because of the generation of ambipolarity, the alteration of the charge carrier polarity or the reduction of electronic couplings. Herein, we utilize indolo[2,3‐a]carbazole (IC) as the model compound and 2,6‐diphenylanthraquinone (DPAO)...

Rare studies of cocrystal engineering have focused on improving carrier mobility of organic semiconductors mainly because of the generation of ambipolarity, the alteration of the charge carrier polarity or the reduction of electronic couplings. Herein, we utilize indolo[2,3‐a]carbazole (IC) as the model compound and 2,6‐diphenylanthraquinone (DPAO)...

Typical organic photovoltaic semiconductors exhibit high exciton binding energy (Eb, typically >300 meV), hindering the development of organic solar cells based on a single photovoltaic material (SPM-OSCs). Herein, compared with the control molecule (Y6), Y6Se with selenium substitution exhibits reduced Eb and faster relaxation of the exciton state...

The device stability of the devices based on thermally active delayed fluorescence is still unsatisfactory, although their efficiencies of the reported devices have reached those of phosphorescent emitters for application. Reducing the triplet related nonradiative process is the most efficient method to enhance the device stability. In this work, w...

The development of high‐efficient red thermally activated delayed fluorescent (TADF) materials is crucial to expanding their applications. Here, the acceptor reconstruction strategies of acceptor bonding and acceptor fusing in donor–acceptor‐type materials to modulate their nonradiative deactivation process and emission color for expanding high‐eff...

High‐performance solar‐blind photodetectors are widely studied due to their unique significance in military and industrial applications. Yet the rational molecular design for materials to possess strong absorption in solar‐blind region is rarely addressed. Here, an organic solar‐blind photodetector is reported by designing a novel asymmetric molecu...

Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to a small number of OSCs, seriously limiting their general application. Herein, we reveal a novel p-doping mechanism by investigating the interacti...

Electrical conductivity is one of the key parameters for organic thermoelectrics and depends on both the concentration and mobility of charge carriers. To increase the carrier concentration, molecular dopants have to be added into organic semiconductor materials, whereas the introduction of dopants can influence the molecular packing structures and...

The efficiency and lifetime are critical to the development of high-quality organic light-emitting diodes (OLEDs). Herein, four dual-acceptor typed thermally activated delayed fluorescence (TADF) emitters (DTXO-PhCz2, DTXO-PhCz4, DTXO-TPA2 and DTXO-TPA4) with emission from yellow to red were designed by taking triphenylamine or N-phenylcarbazole as...