High‐Efficiency All‐Small‐Molecule Organic Solar Cells Based on an Organic Molecule Donor with Alkylsilyl‐Thienyl Conjugated Side Chains

Two medium‐bandgap p‐type organic small molecules H21 and H22 with an alkylsily‐thienyl conjugated side chain on benzo[1,2‐b:4,5‐b′]dithiophene central units are synthesized and used as donors in all‐small‐molecule organic solar cells (SM‐OSCs) with a narrow‐bandgap n‐type small molecule 2,2′‐((2Z,2′Z)‐((4,4,9,9‐tetrahexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (IDIC) as the acceptor. In comparison to H21 with 3‐ethyl rhodanine as the terminal group, H22 with cyanoacetic acid esters as the terminal group shows blueshifted absorption, higher charge‐carrier mobility and better 3D charge pathway in blend films. The power conversion efficiency (PCE) of the SM‐OSCs based on H22:IDIC reaches 10.29% with a higher open‐circuit voltage of 0.942 V and a higher fill factor of 71.15%. The PCE of 10.29% is among the top efficiencies of nonfullerene SM‐OSCs reported in the literature to date.     

End-Group Engineering of Chlorine-Trialkylsiylthienyl Chain-Substituted Small-Molecule Donors for High-Efficiency Ternary Solar Cells

Ternary architecture has been widely demonstrated as a facile and efficient strategy to boost the performance of organic solar cells (OSCs). However, the rational design of the third component with suitable core and end-group modification is still a challenge. Herein, two new small-molecule (SM) donors BT-CN and BT-ER, featuring the identical conjugated backbone with distinct end group, have been designed, synthesized, and introduced into the PM6:Y6 binary system as the second donor. Both molecules exhibit complementary absorption and good miscibility with PM6, contributing to the nanofibrous phases and strong face-on molecular packing. Importantly, the incorporation of BT-CN/BT-ER has significantly facilitated charge collection and transportation with remarkable suppression of carrier recombination. As a result, ternary OSCs with 20 wt% BT-CN/BT-ER achieved a PCE of 16.8%/17.22% with synchronously increased open-circuit voltage (V_OC), short-circuit current density (J_SC) and fill factor (FF). Moreover, replacing Y6 with L8-BO further improves the PCE to 18.05%/18.11%, indicating the universality of both molecules as the third component. This work demonstrates not only two efficient SM donors with 4,8-bis(4-chloro-5-(tripropylsilyl)thiophen-2-yl) benzo[1,2-b:4,5-b′]dithiophene (BDTT-SiCl) as the core but also end group modification strategy to fine-tune the absorption spectrum, molecular packing, and energy levels of SM donors to construct high-performance ternary OSCs.     

Highly Efficient Ternary‐Blend Polymer Solar Cells Enabled by a Nonfullerene Acceptor and Two Polymer Donors with a Broad Composition Tolerance

In this work, highly efficient ternary‐blend organic solar cells (TB‐OSCs) are reported based on a low‐bandgap copolymer of PTB7‐Th, a medium‐bandgap copolymer of PBDB‐T, and a wide‐bandgap small molecule of SFBRCN. The ternary‐blend layer exhibits a good complementary absorption in the range of 300–800 nm, in which PTB7‐Th and PBDB‐T have excellent miscibility with each other and a desirable phase separation with SFBRCN. In such devices, there exist multiple energy transfer pathways from PBDB‐T to PTB7‐Th, and from SFBRCN to the above two polymer donors. The hole‐back transfer from PTB7‐Th to PBDB‐T and multiple electron transfers between the acceptor and the donor materials are also observed for elevating the whole device performance. After systematically optimizing the weight ratio of PBDB‐T:PTB7‐Th:SFBRCN, a champion power conversion efficiency (PCE) of 12.27% is finally achieved with an open‐circuit voltage (V _oc) of 0.93 V, a short‐circuit current density (J _sc) of 17.86 mA cm^?2, and a fill factor of 73.9%, which is the highest value for the ternary OSCs reported so far. Importantly, the TB‐OSCs exhibit a broad composition tolerance with a high PCE over 10% throughout the whole blend ratios.     

16.67% Rigid and 14.06% Flexible Organic Solar Cells Enabled by Ternary Heterojunction Strategy

Ternary heterojunction strategies appear to be an efficient approach to improve the efficiency of organic solar cells (OSCs) through harvesting more sunlight. Ternary OSCs are fabricated by employing wide bandgap polymer donor (PM6), narrow bandgap nonfullerene acceptor (Y6), and PC₇₁BM as the third component to tune the light absorption and morphologies of the blend films. A record power conversion efficiency (PCE) of 16.67% (certified as 16.0%) on rigid substrate is achieved in an optimized PM6:Y6:PC₇₁BM blend ratio of 1:1:0.2. The introduction of PC₇₁BM endows the blend with enhanced absorption in the range of 300–500 nm and optimises interpenetrating morphologies to promote photogenerated charge dissociation and extraction. More importantly, a PCE of 14.06% for flexible ITO‐free ternary OSCs is obtained based on this ternary heterojunction system, which is the highest PCE reported for flexible state‐of‐the‐art OSCs. A very promising ternary heterojunction strategy to develop highly efficient rigid and flexible OSCs is presented.     

Ternary Organic Solar Cells with Efficiency >16.5% Based on Two Compatible Nonfullerene Acceptors

A ternary structure has been demonstrated as being an effective strategy to realize high power conversion efficiency (PCE) in organic solar cells (OSCs); however, general materials selection rules still remain incompletely understood. In this work, two nonfullerene small‐molecule acceptors 3TP3T‐4F and 3TP3T‐IC are synthesized and incorporated as a third component in PM6:Y6 binary blends. The photovoltaic behaviors in the resultant ternary OSCs differ significantly, despite the comparable energy levels. It is found that incorporation of 15% 3TP3T‐4F into the PM6:Y6 blend results in facilitating exciton dissociation, increasing charge transport, and reducing trap‐assisted recombination. All these features are responsible for the enlarged PCE of 16.7% (certified as 16.2%) in the PM6:Y6:3TP3T‐4F ternary OSCs, higher than that (15.6%) in the 3TP3T‐IC containing ternary devices. The performance differences are mainly ascribed to the compatibility between the third component and the host materials. The 3TP3T‐4F guest acceptor exhibits an excellent compatibility with Y6, tending to form well‐mixed phases in the ternary blend without disrupting the favored bicontinuous transport networks, whereas 3TP3T‐IC displays a morphological incompatibility with Y6. This work highlights the importance of considering the compatibility for materials selection toward high‐efficiency ternary organic OSCs.     

Over 14% Efficiency in Organic Solar Cells Enabled by Chlorinated Nonfullerene Small‐Molecule Acceptors

To make organic solar cells (OSCs) more competitive in the diverse photovoltaic cell technologies, it is very important to demonstrate that OSCs can achieve very good efficiencies and that their cost can be reduced. Here, a pair of nonfullerene small‐molecule acceptors, IT‐2Cl and IT‐4Cl, is designed and synthesized by introducing easy‐synthesis chlorine substituents onto the indacenodithieno[3,2‐b]thiophene units. The unique feature of the large dipole moment of the C? Cl bond enhances the intermolecular charge‐transfer effect between the donor–acceptor structures, and thus expands the absorption and down shifts the molecular energy levels. Meanwhile, the introduction of C? Cl also causes more pronounced molecular stacking, which also helps to expand the absorption spectrum. Both of the designed OSCs devices based on two acceptors can deliver a power conversion efficiency (PCE) greater than 13% when blended with a polymer donor with a low‐lying highest occupied molecular orbital level. In addition, since IT‐2Cl and IT‐4Cl have very good compatibility, a ternary OSC device integrating these two acceptors is also fabricated and obtains a PCE greater than 14%. Chlorination demonstrates effective ability in enhancing the device performance and facile synthesis route, which both deserve further exploitation in the modification of photovoltaic materials.     

Dithieno[3,2‐b:2′,3′‐d]pyrrol Fused Nonfullerene Acceptors Enabling Over 13% Efficiency for Organic Solar Cells

A new electron‐rich central building block, 5,5,12,12‐tetrakis(4‐hexylphenyl)‐indacenobis‐(dithieno[3,2‐b:2′,3′‐d]pyrrol) (INP), and two derivative nonfullerene acceptors (INPIC and INPIC‐4F) are designed and synthesized. The two molecules reveal broad (600–900 nm) and strong absorption due to the satisfactory electron‐donating ability of INP. Compared with its counterpart INPIC, fluorinated nonfullerene acceptor INPIC‐4F exhibits a stronger near‐infrared absorption with a narrower optical bandgap of 1.39 eV, an improved crystallinity with higher electron mobility, and down‐shifted highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Organic solar cells (OSCs) based on INPIC‐4F exhibit a high power conversion efficiency (PCE) of 13.13% and a relatively low energy loss of 0.54 eV, which is among the highest efficiencies reported for binary OSCs in the literature. The results demonstrate the great potential of the new INP as an electron‐donating building block for constructing high‐performance nonfullerene acceptors for OSCs.     

Halogen-Free Donor Polymers Based on Dicyanobenzotriazole with Low Energy Loss and High Efficiency in Organic Solar Cells

Halogenation of organic semiconductors is an efficient strategy for improving the performance of organic solar cells (OSCs), while the introduction of halogens usually involves complex synthetic process and serious environment pollution problems. Herein, three halogen-free ternary copolymer donors (PCNx, x = 3, 4, 5) based on electron-withdrawing dicyanobenzotriazole are reported. When blended with the Y6, PCN3 with strong interchain interactions results in appropriate crystallinity and thermodynamic miscibility of the blend film. Grazing-incidence wide-angle X-ray scattering measurements indicate that PCN3 has more ordered arrangement and stronger π–π stacking than previous PCN2. Fourier-transform photocurrent spectroscopy and external quantum efficiency of electroluminescence measurements show that PCN3-based OSCs have lower energy loss than PCN2, which leads to their higher open-circuit voltage (0.873 V). The device based on PCN3 reaches power conversion efficiency (PCE) of 15.33% in binary OSCs, one of the highest values for OSCs with halogen-free donor polymers. The PCE of 17.80% and 18.10% are obtained in PM6:PCN3:Y6 and PM6:PCN3:BTP-eC9 ternary devices, much higher than those of PM6:Y6 (16.31%) and PM6:BTP-eC9 (17.33%) devices. Additionally, this ternary OSCs exhibit superior stability compared to binary host system. This work gives a promising path for halogen-free donor polymers to achieve low energy loss and high PCE.     

Single‐Junction Binary‐Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency

A new fluorinated nonfullerene acceptor, ITIC‐Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end‐capping group 1,1‐dicyanomethylene‐3‐indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push–pull effect between the donor unit indacenodithieno[3,2‐b]thiophene and the acceptor unit IC due to electron‐withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short‐circuit current density (J _SC). On the other hand, incorporation of F would improve intermolecular interactions through C? F···S, C? F···H, and C? F···π noncovalent interactions and enhance electron mobility, which is beneficial to enhancing J _SC and fill factor. Indeed, the results show that fluorinated ITIC‐Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC‐Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC‐Th1 electron acceptor and a wide‐bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC‐Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene‐based single‐junction binary‐blend OSCs. Moreover, the OSCs based on FTAZ:ITIC‐Th1 show much better efficiency and better stability than the control devices based on FTAZ:PC₇₁BM (PCE = 5.22%).     

Naphthodithiophene‐Based Nonfullerene Acceptor for High‐Performance Organic Photovoltaics: Effect of Extended Conjugation

Naphtho[1,2‐b:5,6‐b′]dithiophene is extended to a fused octacyclic building block, which is end capped by strong electron‐withdrawing 2‐(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)malononitrile to yield a fused‐ring electron acceptor (IOIC2) for organic solar cells (OSCs). Relative to naphthalene‐based IHIC2, naphthodithiophene‐based IOIC2 with a larger π‐conjugation and a stronger electron‐donating core shows a higher lowest unoccupied molecular orbital energy level (IOIC2: ?3.78 eV vs IHIC2: ?3.86 eV), broader absorption with a smaller optical bandgap (IOIC2: 1.55 eV vs IHIC2: 1.66 eV), and a higher electron mobility (IOIC2: 1.0 × 10^?3 cm² V^?1 s^?1 vs IHIC2: 5.0 × 10^?4 cm² V^?1 s^?1). Thus, IOIC2‐based OSCs show higher values in open‐circuit voltage, short‐circuit current density, fill factor, and thereby much higher power conversion efficiency (PCE) values than those of the IHIC2‐based counterpart. In particular, as‐cast OSCs based on FTAZ: IOIC2 yield PCEs of up to 11.2%, higher than that of the control devices based on FTAZ: IHIC2 (7.45%). Furthermore, by using 0.2% 1,8‐diiodooctane as the processing additive, a PCE of 12.3% is achieved from the FTAZ:IOIC2 ‐ based devices, higher than that of the FTAZ:IHIC2 ‐ based devices (7.31%). These results indicate that incorporating extended conjugation into the electron‐donating fused‐ring units in nonfullerene acceptors is a promising strategy for designing high‐performance electron acceptors.     

High‐Performance Nonfullerene Polymer Solar Cells based on Imide‐Functionalized Wide‐Bandgap Polymers

High‐performance nonfullerene polymer solar cells (PSCs) are developed by integrating the nonfullerene electron‐accepting material 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophne) (ITIC) with a wide‐bandgap electron‐donating polymer PTzBI or PTzBI‐DT, which consists of an imide functionalized benzotriazole (TzBI) building block. Detailed investigations reveal that the extension of conjugation can affect the optical and electronic properties, molecular aggregation properties, charge separation in the bulk‐heterojunction films, and thus the overall photovoltaic performances. Single‐junction PSCs based on PTzBI:ITIC and PTzBI‐DT:ITIC exhibit remarkable power conversion efficiencies (PCEs) of 10.24% and 9.43%, respectively. To our knowledge, these PCEs are the highest efficiency values obtained based on electron‐donating conjugated polymers consisting of imide‐functionalized electron‐withdrawing building blocks. Of particular interest is that the resulting device based on PTzBI exhibits remarkable PCE of 7% with the thickness of active layer of 300 nm, which is among the highest values of nonfullerene PSCs utilizing thick photoactive layer. Additionally, the device based on PTzBI:ITIC exhibits prominent stability, for which the PCE remains as 9.34% after thermal annealing at 130 °C for 120 min. These findings demonstrate the great promise of using this series of wide‐bandgap conjugated polymers as electron‐donating materials for high‐performance nonfullerene solar cells toward high‐throughput roll‐to‐roll processing technology.     

Over 15.7% Efficiency of Ternary Organic Solar Cells by Employing Two Compatible Acceptors with Similar LUMO Levels

Efficient organic solar cells (OSCs) are fabricated using polymer PM6 as donor, and IPTBO‐4Cl and MF1 as acceptors. The power conversion efficiency (PCE) of IPTBO‐4Cl based and MF1 based binary OSCs individually arrive to 14.94% and 12.07%, exhibiting markedly different short circuit current density (J_SC) of 23.18 mA cm^?2 versus 17.01 mA cm^?2, fill factor (FF) of 72.17% versus 78.18% and similar open circuit voltage (V_OC) of 0.893 V versus 0.908 V. The two acceptors, IPTBO‐4Cl and MF1, have similar lowest unoccupied molecular orbital levels, which is beneficial for efficient electron transport in the ternary active layer. The PCE of optimized ternary OSCs arrives to 15.74% by incorporating 30 wt% MF1 in acceptors, resulting from the simultaneously increased J_SC of 23.20 mA cm^?2, V_OC of 0.897 V, and FF of 75.64% in comparison with IPTBO‐4Cl based binary OSCs. The gradually increased FFs of ternary OSCs indicate the well‐optimized phase separation and molecular arrangement with MF1 as morphology regulator. This work may provide a new viewpoint for selecting an appropriate third component to achieve efficient ternary OSCs from materials and photovoltaic parameters of two binary OSCs.     

A Highly Efficient Non‐Fullerene Organic Solar Cell with a Fill Factor over 0.80 Enabled by a Fine‐Tuned Hole‐Transporting Layer

With rapid development for tens of years, organic solar cells (OSCs) have attracted much attention for their potential in practical applications. As an important photovoltaic parameter, the fill factor (FF) of OSCs stands for the effectiveness of charge generation and collection, which significantly depends on the properties of the interlayer and active layer. Here, a facile and effective strategy to improve the FF through hole‐transporting layer (HTL) modification is demonstrated. By mixing WO_x nanoparticles with a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) emulsion, the surface free energy of the HTL is improved and the morphology of the active layer is optimized. Benefiting from increased carrier lifetime, a device based on WO_x:PEDOT:PSS HTL exhibits a boosted performance with an FF of 80.79% and power conversion efficiency of 14.57% PCE. The results are certified by the National Institute of Metrology (NIM), which, to date, are the highest values in this field with certification. This work offers a simple and viable option of HTL modification to realize highly efficient OSCs.     

Environmentally Friendly Solvent‐Processed Organic Solar Cells that are Highly Efficient and Adaptable for the Blade‐Coating Method

The power conversion efficiencies (PCEs) of state‐of‐the‐art organic solar cells (OSCs) have increased to over 13%. However, the most commonly used solvents for making the solutions of photoactive materials and the coating methods used in laboratories are not adaptable for future practical production. Therefore, taking a solution‐coating method with environmentally friendly processing solvents into consideration is critical for the practical utilization of OSC technology. In this study, a highly efficient PBTA‐TF:IT‐M‐based device processed with environmentally friendly solvents, tetrahydrofuran/isopropyl alcohol (THF/IPA) and o‐xylene/1‐phenylnaphthalene, is fabricated; a high PCE of 13.1% can be achieved by adopting the spin‐coating method, which is the top result for OSCs. More importantly, a blade‐coated non‐fullerene OSC processed with THF/IPA is demonstrated for the first time to obtain a promising PCE of 11.7%; even for the THF/IPA‐processed large‐area device (1.0 cm²) made by blade‐coating, a PCE of 10.6% can still be maintained. These results are critical for the large‐scale production of highly efficient OSCs in future studies.     

Efficient Semitransparent Organic Solar Cells with Tunable Color enabled by an Ultralow‐Bandgap Nonfullerene Acceptor

Semitransparent organic solar cells (OSCs) show attractive potential in power‐generating windows. However, the development of semitransparent OSCs is lagging behind opaque OSCs. Here, an ultralow‐bandgap nonfullerene acceptor, “IEICO‐4Cl”, is designed and synthesized, whose absorption spectrum is mainly located in the near‐infrared region. When IEICO‐4Cl is blended with different polymer donors (J52, PBDB‐T, and PTB7‐Th), the colors of the blend films can be tuned from purple to blue to cyan, respectively. Traditional OSCs with a nontransparent Al electrode fabricated by J52:IEICO‐4Cl, PBDB‐T:IEICO‐4Cl, and PTB7‐Th:IEICO‐4Cl yield power conversion efficiencies (PCE) of 9.65 ± 0.33%, 9.43 ± 0.13%, and 10.0 ± 0.2%, respectively. By using 15 nm Au as the electrode, semitransparent OSCs based on these three blends also show PCEs of 6.37%, 6.24%, and 6.97% with high average visible transmittance (AVT) of 35.1%, 35.7%, and 33.5%, respectively. Furthermore, via changing the thickness of Au in the OSCs, the relationship between the transmittance and efficiency is studied in detail, and an impressive PCE of 8.38% with an AVT of 25.7% is obtained, which is an outstanding value in the semitransparent OSCs.     

12.5% Flexible Nonfullerene Solar Cells by Passivating the Chemical Interaction Between the Active Layer and Polymer Interfacial Layer

Nonfullerene (NF) organic solar cells (OSCs) have been attracting significant attention in the past several years. It is still challenging to achieve high‐performance flexible NF OSCs. NF acceptors are chemically reactive and tend to react with the low‐temperature‐processed low‐work‐function (low‐WF) interfacial layers, such as polyethylenimine ethoxylated (PEIE), which leads to the “S” shape in the current‐density characteristics of the cells. In this work, the chemical interaction between the NF active layer and the polymer interfacial layer of PEIE is deactivated by increasing its protonation. The PEIE processed from aqueous solution shows more protonated N⁺ than that processed from isopropyl alcohol solution, observed from X‐ray photoelectron spectroscopy. NF solar cells (active layer: PCE‐10:IEICO‐4F) with the protonated PEIE interfacial layer show an efficiency of 13.2%, which is higher than the reference cells with a ZnO interlayer (12.6%). More importantly, the protonated PEIE interfacial layer processed from aqueous solution does not require a further thermal annealing treatment (only processing at room temperature). The room‐temperature processing and effective WF reduction enable the demonstration of high‐performance (12.5%) flexible NF OSCs.     

A Self‐Organized Poly(vinylpyrrolidone)‐Based Cathode Interlayer in Inverted Fullerene‐Free Organic Solar Cells

Herein, poly(vinylpyrrolidone) (PVP) is used as the cathode interlayer (CIL) through the self‐organization method in inverted organic solar cells (OSCs). By coating a solution of PVP and active layer materials onto a glass/indium tin oxide (ITO) substrate, the PVP can segregate to the near ITO side due to its high surface energy and strong intermolecular interaction with the ITO electrode. The power conversion efficiency (PCE) of the obtained OSC device reaches 13.3%, much higher than that of the control device with a PCE of only 10.1%. The improvement results from the increased exciton dissociation efficiency and the depressed trap‐assisted recombination, which can be attributed to the reduced work function of the cathode by the self‐organized PVP. Additionally, the molecular weight of the PVP has almost no influence on the device performance, and the PVP‐modified device presents superior stability. This method can also be applied in other highly efficient fullerene‐free OSCs, and with a fine selection of the active layer, a high PCE of 14.0% is obtained. Overall, this work demonstrates the great potential of the PVP‐based CIL in inverted OSCs fabricated via the self‐organization method.     

Over 12% Efficiency Nonfullerene All‐Small‐Molecule Organic Solar Cells with Sequentially Evolved Multilength Scale Morphologies

In this paper, two near‐infrared absorbing molecules are successfully incorporated into nonfullerene‐based small‐molecule organic solar cells (NFSM‐OSCs) to achieve a very high power conversion efficiency (PCE) of 12.08%. This is achieved by tuning the sequentially evolved crystalline morphology through combined solvent additive and solvent vapor annealing, which mainly work on ZnP‐TBO and 6TIC, respectively. It not only helps improve the crystallinity of the ZnP‐TBO and 6TIC blend, but also forms multilength scale morphology to enhance charge mobility and charge extraction. Moreover, it simultaneously reduces the nongeminate recombination by effective charge delocalization. The resultant device performance shows remarkably enhanced fill factor and J_sc. These result in a very respectable PCE, which is the highest among all NFSM‐OSCs and all small‐molecule binary solar cells reported so far.     

A Porphyrin‐Based Conjugated Polymer for Highly Efficient In Vitro and In Vivo Photothermal Therapy

Conjugated polymers have been increasingly studied for photothermal therapy (PTT) because of their merits including large absorption coefficient, facile tuning of exciton energy dissipation through nonradiative decay, and good therapeutic efficacy. The high photothermal conversion efficiency (PCE) is the key to realize efficient PTT. Herein, a donor–acceptor (D–A) structured porphyrin‐containing conjugated polymer (PorCP) is reported for efficient PTT in vitro and in vivo. The D–A structure introduces intramolecular charge transfer along the backbone, resulting in redshifted Q band, broadened absorption, and increased extinction coefficient as compared to the state‐of‐art porphyrin‐based photothermal reagent. Through nanoencapsulation, the dense packing of a large number of PorCP molecules in a single nanoparticle (NP) leads to favorable nonradiative decay, good photostability, and high extinction coefficient of 4.23 × 10⁴m ^?1 cm^?1 at 800 nm based on porphyrin molar concentration and the highest PCE of 63.8% among conjugated polymer NPs. With the aid of coloaded fluorescent conjugated polymer, the cellular uptake and distribution of the PorCP in vitro can be clearly visualized, which also shows effective photothermal tumor ablation in vitro and in vivo. This research indicates a new design route of conjugated polymer‐based photothermal therapeutic materials for potential personalized theranostic nanomedicine.     

High‐Performance Long‐Term‐Stable Dopant‐Free Perovskite Solar Cells and Additive‐Free Organic Solar Cells by Employing Newly Designed Multirole π‐Conjugated Polymers

Perovskite solar cells (PSCs) and organic solar cells (OSCs) are promising renewable light‐harvesting technologies with high performance, but the utilization of hazardous dopants and high boiling additives is harmful to all forms of life and the environment. Herein, new multirole π‐conjugated polymers (P1–P3) are developed via a rational design approach through theoretical hindsight, further successfully subjecting them into dopant‐free PSCs as hole‐transporting materials and additive‐free OSCs as photoactive donors, respectively. Especially, P3‐based PSCs and OSCs not only show high power conversion efficiencies of 17.28% and 8.26%, but also display an excellent ambient stability up to 30 d (for PSCs only), owing to their inherent superior optoelectronic properties in their pristine form. Overall, the rational approach promises to support the development of environmentally and economically sustainable PSCs and OSCs.