Chen Weijie

The sp²‐nitrogen positions in the n‐type (D–A₁–D–A₂) conjugated polymers have a significant impact on the photovoltaic properties of p–i–n perovskite solar cells when they are used as an electron transporting layer. pBTTz with the HOMO and LUMO levels well‐matched with the valence and conduction bands of the perovskite layer, respectively, shows excellent power conversion efficiency and high stability.

Abstract

It is highly desirable to employ n‐type polymers as electron transporting layers (ETLs) in inverted perovskite solar cells (PSCs) due to their good electron mobility, high hydrophobicity, and simplicity of film forming. In this research, the capability of three n‐type donor–acceptor₁–donor–acceptor₂ (D–A₁–D–A₂) conjugated polymers (pBTT, pBTTz, and pSNT) is first explored as ETLs because these polymers possess electron mobilities as high as 0.92, 0.46, and 4.87 cm² (Vs)⁻¹ in n‐channel organic transistors, respectively. The main structural difference among pBTT, pBTTz, and pSNT is the position of sp²‐nitrogen atoms (sp²‐N) in the polymer main chains. Therefore, the effect of different substitution positions on the PSC performances is comprehensively studied. The as‐fabricated p–i–n PSCs with pBTT, pBTTz, and pSNT as ETLs show the maximum photoconversion efficiencies of 12.8%, 14.4%, and 12.0%, respectively. To be highlighted, pBTTz‐based device can maintain 80% of its stability after ten days due to its good hydrophobicity, which is further confirmed by a contact angle technique. More importantly, the pBTTz‐based device shows a neglected hysteresis. This study reveals that the n‐type polymers can be promising candidates as ETLs to approach solution‐processed highly‐efficient inverted PSCs.

Novel CsPbI₃ perovskite quantum dots (QDs) are prepared by ligand exchange with 2‐aminoethanethiol (AET), which shows excellent carrier mobility and stability against moisture and ultraviolet light. Photodetectors based on the AET‐CsPbI₃ QD films exhibit remarkable performance and excellent storage as well as thermal and photo stability without any encapsulation.

Abstract

A surface engineering strategy aimed at improving the stability of CsPbI₃ perovskite quantum dots (QDs) both in solution and as films is demonstrated, by performing partial ligand exchange with a short chain ligand, 2‐aminoethanethiol (AET), in place of the original long chain ligands, oleic acid (OA) and oleylamine (OAm), used in synthesis. This results in the formation of a compact ligand barrier around the particles, which prevents penetration of water molecules and thus degradation of the films and, in addition, at the same time improves carrier mobility. Moreover, the AET ligand can passivate surface traps of the QDs, leading to an enhanced photoluminescence (PL) efficiency. As a result, AET‐CsPbI₃ QDs maintain their optical performance both in solution and as films, retaining more than 95% of the initial PL intensity in water after 1 h, and under ultraviolet irradiation for 2 h. Photodetectors based on the AET‐CsPbI₃ QD films exhibit remarkable performance, such as high photoresponsivity (105 mA W⁻¹) and detectivity (5 × 10¹³ Jones at 450 nm and 3 × 10¹³ Jones at 700 nm) without an external bias. The photodetectors also show excellent stability, retaining more than 95% of the initial responsivity in ambient air for 40 h without any encapsulation.

A meta‐alkoxylphenylated dithieno[3,2‐b:2′,3′‐d]pyrrol‐fused nonfullerene acceptor, featuring predominant face‐on orientation in films, enables high‐efficiency as‐cast thick organic solar cells (OSCs). Binary blends with PBDB‐T contributes to a 12.1% power conversion efficiency. Addition of 15 wt% PC₇₁BM renders an efficiency of 14%, among the records for as‐cast single‐junction OSCs. All devices exhibit thickness insensitivity in an active layer thickness window of 82–202 nm.

Abstract

Molecular orientation and π–π stacking of nonfullerene acceptors (NFAs) determine its domain size and purity in bulk‐heterojunction blends with a polymer donor. Two novel NFAs featuring an indacenobis(dithieno[3,2‐b:2ʹ,3ʹ‐d]pyrrol) core with meta‐ or para‐alkoxyphenyl sidechains are designed and denoted as m‐INPOIC or p‐INPOIC, respectively. The impact of the alkoxyl group positioning on molecular orientation and photovoltaic performance of NFAs is revealed through a comparison study with the counterpart (INPIC‐4F) bearing para‐alkylphenyl sidechains. With inward constriction toward the conjugated backbone, m‐INPOIC presents predominant face‐on orientation to promote charge transport. The as‐cast organic solar cells (OSCs) by blending m‐INPOIC and PBDB‐T as active layers exhibit a power conversion efficiency (PCE) of 12.1%. By introducing PC₇₁BM as the solid processing‐aid, the ternary OSCs are further optimized to deliver an impressive PCE of 14.0%, which is among the highest PCEs for as‐cast single‐junction OSCs reported in literature to date. More attractively, PBDB‐T: m‐INPOIC:PC₇₁BM based OSCs exhibit over 11% PCEs even with an active layer thickness over 300 nm. And the devices can retain over 95% of PCE after storage for 20 days. The outstanding tolerance to film thickness and outstanding stability of the as‐cast devices make m‐INPOIC a promising candidate NFA for large‐scale solution‐processable OSCs.

Here, how attractive optical and electrical properties of perovskite materials are translated into the high performance of perovskite‐based light‐emitting diodes (PeLEDs) is discussed, and working mechanisms and optimization approaches of both perovskite materials and the respective devices are analyzed. Several challenges such as performance of blue PeLEDs, the environmental and operational stability of PeLEDs, and the toxicity issues of lead halide perovskites are considered.

Abstract

As the requirements and expectation for displays in society are growing, higher standards of the display technology are proposed, including wider color gamut, higher color purity, and higher resolution. The recent emergence of light‐emitting halide perovskites has come with numerous advantages, such as high charge‐carrier mobility, tunable emission wavelength, narrow emission linewidth, and intrinsically high photoluminescence quantum yield. Recent advancement of perovskite‐based light‐emitting diodes (PeLEDs) as a promising technology for next‐generation displays is reviewed. Here, how the attractive optical and electrical properties of perovskite materials can be translated into high PeLED performance are discussed, and working mechanisms and optimization approaches of both perovskite materials and the respective devices are analyzed. On the material side this includes the control of size and composition of perovskites grains and nanocrystals, surface and interface passivation, doping and alloying, while on the device side this includes the interfacial engineering and energy level adjustments, and photon emission enhancement. Several challenges such as performance of blue PeLEDs, the environmental and operational stability of PeLEDs, and the toxicity issues of lead halide perovskites are discussed, and perspectives on future developments of perovskite materials and PeLEDs for the display technology are offered.

Imaging and mapping characterization techniques are used to understand the fundamental properties that allow lead halide perovskites to have excellent performance metrics. In this work, commonly‐used and specialized tools that are used characterize halide perovskite materials and solar cells, including electron microscopy, atomic force microscopy, synchrotron‐based X‐ray mapping, and ultrafast and photoluminescence mapping are reviewed.

Abstract

Perovskite solar cells (PSCs) have attracted much attention as efficiencies have gone beyond 24%. To achieve these impressive numbers, the PSC scientific community is working to improve the perovskite optoelectronic properties. Imaging and mapping characterization techniques have been widely used to understand the fundamental properties that allow lead halide perovskites to achieve high performance. In this review, these techniques are evaluated, from simple tools, such as electron microscopy, to more complex systems that include atomic force microscopy, synchrotron‐based X‐ray mapping, and ultrafast and photoluminescence mapping. These tools have helped understand lead halide perovskites and their impressive optoelectronic properties, which make them outstanding materials for solar cell applications.

Hysteresis in the dark, attributable to bias induced degradation of the p‐type interface, is investigated and eliminated in NiO‐based inverted perovskite solar cells. Enhanced stability to forward bias is obtained with the introduction of a low‐temperature hybrid magnesium‐based interlayer.

Abstract

In perovskite solar cells (PSCs), the interfaces are a weak link with respect to degradation. Electrochemical reactivity of the perovskite's halides has been reported for both molecular and polymeric hole selective layers (HSLs), and here it is shown that also NiO brings about this decomposition mechanism. Employing NiO as an HSL in p–i–n PSCs with power conversion efficiency (PCE) of 16.8%, noncapacitive hysteresis is found in the dark, which is attributable to the bias‐induced degradation of perovskite/NiO interface. The possibility of electrochemically decoupling NiO from the perovskite via the introduction of a buffer layer is explored. Employing a hybrid magnesium‐organic interlayer, the noncapacitive hysteresis is entirely suppressed and the device's electrical stability is improved. At the same time, the PCE is improved up to 18% thanks to reduced interfacial charge recombination, which enables more efficient hole collection resulting in higher V _oc and FF.

Vacuum codeposition can be used to fabricate mixed tin–lead formamidinium iodide perovskite. The three precursor thermal sources are combined with an additional source to incorporate tin fluoride as an additive, which improves film formation and reduces tin oxidation. The vacuum‐deposited perovskite films are integrated in devices with >14% photovoltaic efficiency as a proof of concept.

The tunability of the optoelectrical properties upon compositional modification is a key characteristic of metal halide perovskites. In particular, bandgaps narrower than those in conventional lead‐based perovskites are essential to achieve the theoretical efficiency limit of single‐absorber solar cells, as well as develop multijunction tandem devices. Herein, the solvent‐free vacuum deposition of a narrow bandgap perovskite based on tin–lead metal and formamidinium cation is reported. Pinhole‐free films with 1.28 eV bandgap are obtained by thermal codeposition of precursors. The optoelectrical quality of these films is demonstrated by their use in solar cells with a power conversion efficiency of 13.98%.

Energy and charge transfer in ternary organic solar cells (OSC) are investigated by transient spectroscopy. Depending on the excitation wavelength, either exclusive charge transfer or a competition between energy and charge transfer is observed. The presence of PC₇₁BM in the ternary OSC increases the absorption in the UV spectral region and indirectly enhances the electron mobility of ICC6 in the blend.

Abstract

Ternary organic solar cells (OSCs) are among the best‐performing organic photovoltaic devices to date, largely due to the recent development of nonfullerene acceptors. However, fullerene molecules still play an important role in ternary OSC systems, since, for reasons not well understood, they often improve the device performance, despite their lack of absorption. Here, the photophysics of a prototypical ternary small‐molecule OSC blend composed of the donor DR3, the nonfullerene acceptor ICC6, and the fullerene derivative PC₇₁BM is studied by ultrafast spectroscopy. Surprisingly, it is found that after excitation of PC₇₁BM, ultrafast singlet energy transfer to ICC6 competes efficiently with charge transfer. Subsequently, singlets on ICC6 undergo hole transfer to DR3, resulting in free charge generation. Interestingly, PC₇₁BM improves indirectly the electron mobility of the ternary blend, while electrons reside predominantly in ICC6 domains as indicated by fast spectroscopy. The improved mobility facilitates charge carrier extraction, in turn leading to higher device efficiencies of the ternary compared to binary solar cells. Using the (photo)physical parameters obtained from (transient) spectroscopy and charge transport measurements, the device's current–voltage characteristics are simulated and it is demonstrated that the parameters accurately reproduce the experimentally measured device performance.

A ternary material system–enabled 16.5% efficiency fullerene‐free organic photovoltaic cell is designed with a structurally similar higher‐LUMO‐level guest nonfullerene acceptor. The homogeneous fine morphology and the π–π stacking pattern enable the two acceptors to synergize, obtaining increased open‐circuit voltage, short‐circuit current, and fill factor.

Abstract

Ternary approaches to solar cell design utilizing a small bandgap nonfullerene acceptor as the near infrared absorber to increase the short‐circuit current density always decreases the open‐circuit voltage. Herein, a highly efficient polymer solar cell with an impressive efficiency of 16.28 ± 0.20% enabled by an effective voltage‐increased ternary blended fullerene‐free material approach is reported. In this approach, the structural similarity between the host and the higher‐LUMO‐level guest enables the two acceptors to be synergized, obtaining increased open‐circuit voltage and fill factor and a small increase of short‐circuit current density. The same beneficial effects are demonstrated by using two host binary systems. The homogeneous fine film morphologies and the π–π stacking patterns of the host blend are well maintained, while larger donor and acceptor phases and increased lamellar crystallinity, increased charge mobilities, and reduced monomolecular recombination can be achieved upon addition of the guest nonfullerene acceptor. The increased charge mobilities and reduced monomolecular recombination not only contribute to the improved fill factor but also enable the best devices to be fabricated with a relatively thicker ternary blended active layer (110 vs 100 nm). This, combined with the absorption from the added guest acceptor, contribute to the increased short‐circuit current.

Quantum dot solace: A hybrid ternary organic solar cell incorporating lead halide perovskite quantum dots boosts conversion efficiency. It exhibits improved exciton dissociation and suppressed recombination.

Abstract

The facile synthesis, solution‐processability, and outstanding optoelectronic properties of emerging colloidal lead halide perovskite quantum dots (LHP QDs) makes them ideal candidates for scalable and inexpensive optoelectronic applications, including photovoltaic (PV) devices. The first demonstration of integrating CsPbI₃ QDs into a conventional organic solar cell (OSC) involves embedding the LHP QDs in a donor–acceptor (PTB7‐Th:PC₇₁BM) bulk heterojunction. Optimizing the loading amount at 3 wt %, we demonstrate a power conversion efficiency of 10.8 %, which is a 35 % increase over control devices, and is a record amongst hybrid ternary OSCs. Detailed investigation into the mechanisms behind the performance enhancement shows that increased light absorption is not a factor, but that increased exciton separation in the acceptor phase and reduced recombination are responsible.

Publication date: October 2019

Source: Nano Energy, Volume 64

Author(s): Tao Wang, Gang Lian, Liping Huang, Fei Zhu, Deliang Cui, Qilong Wang, Qingbo Meng, Haihui Jiang, GuangJun Zhou, Ching-Ping Wong

Graphical abstract

Two-round pressure-assisted solvent-engineering strategy is designed to achieve remarkable enhancement in grain size (~400 μm²), crystallinity, orientation and, especially, boundary fusion. Crystal growth and boundary welding of MAPbI₃ grains, ascribed to pressure-enhanced ion diffusion and defect elimination, vastly reduce trap density, suppress charge recombination, and thus improve the charge transport. The corresponding photodetectors exhibit superior photoelectric performance at Vis-NIR regions, e.g. ultrahigh on/off ratio, fast response and high detectivity.

Publication date: October 2019

Source: Nano Energy, Volume 64

Author(s): Long Hu, Xun Geng, Simrjit Singh, Junjie Shi, Yicong Hu, Shaoyuan Li, Xinwei Guan, Tengyue He, Xiaoning Li, Zhenxiang Cheng, Robert Patterson, Shujuan Huang, Tom Wu

Graphical abstract

Schematic of (a) champion device with structure of ITO/SnO₂/PCBM/PbSe-PTLE/PbS-EDT/Au demonstrates that ultra-thin PCBM can alleviates charge recombination. (b) The PbSe quantum dot solar cell with device configuration of ITO/SnO₂/PbSe-PTLE/PbS-EDT/Au and ITO/SnO₂/PCBM/PbSe-PTLE/PbS-EDT/Au demonstrate 9.8% and 10.4% efficiency, respectively.

The sp²‐nitrogen positions in the n‐type (D–A₁–D–A₂) conjugated polymers have a significant impact on the photovoltaic properties of p–i–n perovskite solar cells when they are used as an electron transporting layer. pBTTz with the HOMO and LUMO levels well‐matched with the valence and conduction bands of the perovskite layer, respectively, shows excellent power conversion efficiency and high stability.

Abstract

It is highly desirable to employ n‐type polymers as electron transporting layers (ETLs) in inverted perovskite solar cells (PSCs) due to their good electron mobility, high hydrophobicity, and simplicity of film forming. In this research, the capability of three n‐type donor–acceptor₁–donor–acceptor₂ (D–A₁–D–A₂) conjugated polymers (pBTT, pBTTz, and pSNT) is first explored as ETLs because these polymers possess electron mobilities as high as 0.92, 0.46, and 4.87 cm² (Vs)⁻¹ in n‐channel organic transistors, respectively. The main structural difference among pBTT, pBTTz, and pSNT is the position of sp²‐nitrogen atoms (sp²‐N) in the polymer main chains. Therefore, the effect of different substitution positions on the PSC performances is comprehensively studied. The as‐fabricated p–i–n PSCs with pBTT, pBTTz, and pSNT as ETLs show the maximum photoconversion efficiencies of 12.8%, 14.4%, and 12.0%, respectively. To be highlighted, pBTTz‐based device can maintain 80% of its stability after ten days due to its good hydrophobicity, which is further confirmed by a contact angle technique. More importantly, the pBTTz‐based device shows a neglected hysteresis. This study reveals that the n‐type polymers can be promising candidates as ETLs to approach solution‐processed highly‐efficient inverted PSCs.

A meta‐alkoxylphenylated dithieno[3,2‐b:2′,3′‐d]pyrrol‐fused nonfullerene acceptor, featuring predominant face‐on orientation in films, enables high‐efficiency as‐cast thick organic solar cells (OSCs). Binary blends with PBDB‐T contributes to a 12.1% power conversion efficiency. Addition of 15 wt% PC₇₁BM renders an efficiency of 14%, among the records for as‐cast single‐junction OSCs. All devices exhibit thickness insensitivity in an active layer thickness window of 82–202 nm.

Abstract

Molecular orientation and π–π stacking of nonfullerene acceptors (NFAs) determine its domain size and purity in bulk‐heterojunction blends with a polymer donor. Two novel NFAs featuring an indacenobis(dithieno[3,2‐b:2ʹ,3ʹ‐d]pyrrol) core with meta‐ or para‐alkoxyphenyl sidechains are designed and denoted as m‐INPOIC or p‐INPOIC, respectively. The impact of the alkoxyl group positioning on molecular orientation and photovoltaic performance of NFAs is revealed through a comparison study with the counterpart (INPIC‐4F) bearing para‐alkylphenyl sidechains. With inward constriction toward the conjugated backbone, m‐INPOIC presents predominant face‐on orientation to promote charge transport. The as‐cast organic solar cells (OSCs) by blending m‐INPOIC and PBDB‐T as active layers exhibit a power conversion efficiency (PCE) of 12.1%. By introducing PC₇₁BM as the solid processing‐aid, the ternary OSCs are further optimized to deliver an impressive PCE of 14.0%, which is among the highest PCEs for as‐cast single‐junction OSCs reported in literature to date. More attractively, PBDB‐T: m‐INPOIC:PC₇₁BM based OSCs exhibit over 11% PCEs even with an active layer thickness over 300 nm. And the devices can retain over 95% of PCE after storage for 20 days. The outstanding tolerance to film thickness and outstanding stability of the as‐cast devices make m‐INPOIC a promising candidate NFA for large‐scale solution‐processable OSCs.

Lead halide perovskites are promising semiconductors for high-performance photonic devices. Because the refractive index determines the optimal design and performance limit of the semiconductor devices, the refractive index and its change upon external modulations are the most critical properties for advanced photonic applications. Here, we report that the refractive index of halide perovskite CH₃NH₃PbCl₃ shows a distinct decrease with increasing temperature, i.e., a large negative thermo-optic coefficient, which is opposite to those of conventional inorganic semiconductors. By using this negative coefficient, we demonstrate the compensation of thermally induced optical phase shifts occurring in conventional semiconductors. Furthermore, we observe a large and slow refractive index change in CH₃NH₃PbCl₃ during photoirradiation and clarify its origin to be a very low thermal conductivity supported by theoretical analysis. The giant thermo-optic response of CH₃NH₃PbCl₃ facilitates efficient phase modulation of visible light.

Smart photovoltaic windows with distinguished electrical power generation, energy saving, and privacy protection are enabled by coupling of multiresponsive liquid crystal/polymer composite (LCPC) films and semi‐transparent perovskite solar cells (ST‐PSC). In this design, fast and stable multiresponsive LCPC films are utilized as an inside layer to control the transparency, and high‐performance ST‐PSCs as an outside layer to offer energy generation functionality.

Abstract

Smart photovoltaic windows (SPWs) are functional devices possessing the capabilities of electrical power output, energy saving, and privacy protection by managing sunlight under external stimuli and potentially applicable in the fields of energy‐saving buildings, automobiles, and switchable optoelectronics. However, long response time, low power conversion efficiency (PCE), poor stability and cycling performance, and monostimuli responsive behavior restrict their practical applications. To address these issues, high‐efficiency and reliable SPWs are demonstrated by coupling multiresponsive liquid crystal/polymer composite (LCPC) films and semi‐transparent perovskite solar cells (ST‐PSCs). In this design, fast and multiple stimuli‐responsive LCPC films are utilized as an inside layer to control the transparency of SPWs. The ST‐PSCs with competitive PCE and qualified transparency acting as an outside layer offer energy generation functionality. Benefiting from repeatable transparency transition modulated by external stimuli, a series of working modes are achieved in the SPWs providing distinguished and stable energy generation, energy saving, and privacy protection performances.

Ternary polymer solar cells (PSCs) are fabricated with PBDB‐T:PC₇₁BM:INPIC‐Si as the active layers. The power conversion efficiency (PCE) reaches 13.26% for ternary PSCs with 20 wt% PC₇₁BM, which is larger than that for INPIC‐Si or PC₇₁BM‐based PSCs with PCEs of 11.79% or 6.26%. Light absorption, exciton distribution, and film morphology can be simultaneously optimized by incorporating appropriate PC₇₁BM.

Ternary polymer solar cells (PSCs) are designed by incorporating varied PC₇₁BM into a PBDB‐T:INPIC‐Si‐based binary system. The PC₇₁BM incorporation can replenish weak absorption of PBDB‐T and INPIC‐Si in the short wavelength from 300 to 500 nm. Effective charge transport channels can be formed in ternary active layers due to good compatibility of the used materials. The optimized ternary PSCs exhibit a power conversion efficiency (PCE) of 13.26% with short‐circuit current density (J _SC) of 20.98 mA cm⁻², open‐circuit voltage of 0.892 V, and fill factor (FF) of 70.84%. The 13.26% PCE is among the top values for ternary PSCs with fullerene derivative and nonfullerene materials as acceptors. An approximately 12.5% PCE improvement is obtained compared with INPIC‐Si‐based binary PSCs, originating from simultaneously increased J _SC and FF of the optimized ternary PSCs. The balanced photon harvesting is obtained in the whole wavelength range by regulating PC₇₁BM content in acceptors, leading to increased J _SC of ternary PSCs. The molecular arrangement and phase separation are well optimized in ternary blend films, resulting in the enhanced FF of ternary PSCs. The photogenerated exciton distribution is optimized according to optical field distribution of ternary active layers, which further support the J _SC and FF improvement.

Steric hindrance of side chains is purposely introduced in the design of planar nonfullerene acceptors. Compared with IDTT2F bearing bare thiophene bridge unit, IDTCN‐C, IDTCN‐O, and IDTCN‐S with alkyl, alkoxyl, and alkylthio substituted thiophene bridge units, all display favorable face‐on orientation and strong crystallinity. An excellent power conversion efficiency of 13.28% based on PBDB‐T:IDTCN‐O is achieved without any additives or annealing treatments.

Abstract

A series of alkyl, alkoxyl, and alkylthio substituted A–π–D–π–A type nonfullerene acceptors (NFAs) IDTCN‐C, IDTCN‐O, and IDTCN‐S are designed and synthesized. The introduction of a lateral side chain at the outer position of the π bridge unit can endow the terminal moiety with a confined planar conformation due to the steric hindrance. Thus, compared with nonsubstituted NFA (IDTT2F), these acceptors tend to form favorable face‐on orientation and exhibit strong crystallinity as verified with grazing‐incidence wide‐angle X‐ray scattering measurement. Moreover, the variation of side chain can significantly change the lowest unoccupied molecular orbital (LUMO) energy level of acceptors. As state‐of‐the‐art NFAs, a power conversion efficiency of 13.28% (V _oc = 0.91 V, J _sc = 19.96 mA cm⁻², and FF = 73.2%) is obtained for the as‐cast devices based on IDTCN‐O, which is among the highest value reported in literature. The excellent photovoltaic performance for IDTCN‐O can be attributed to its slightly up‐shifted LUMO level and more balanced charge transport. This research demonstrates side chain engineering is an effective way to achieve high efficiency organic solar cells.

The bistricyclic aromatic enes molecules with multiple conformations are selected to further explore the effect of conformation on performance systematically. Then, a machine learning model is used to screen the more matched donor and predict the energy conversion efficiency of the device. A route from microscopic conformation to macroscopic performance design and characterization for organic photovoltaic device is established.

Theoretical predictions of macroscopic performance (power conversion efficiencies [PCEs]) and experimental analyses for microscopic material (conformation) have always urged for organic photovoltaics. A series of acceptors based on multi‐conformation bistricyclic aromatic enes core have been designed. The results suggested that A4‐2, A5‐2, and T4‐2 show the full folded conformation, fitting, and exhibiting advantageous properties of various parts for acceptors effectively, thus getting high V _OC and J _SC (k _CS/k _CR exceeds 10¹²) as well. Their PCEs of devices matching different donors were predicted through machine learning (ML). In traditional device structures and crude environments, a maximum PCE is about seven times higher than original. Herein, a comprehensive investigation, ranging for conformations → donor/acceptor interfaces → morphology → PCEs, is carried out by pure theoretical methods. Therefore, this quantitative micro‐analysis combined with the ML intelligent prediction leads to a new approach in the development of the next generation of nonfullerene acceptors.

Nature Communications, Published online: 17 July 2019; doi:10.1038/s41467-019-11087-y