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Designing organic semiconductors for practical applications in organic solar cells, organic field-effect transistors, and organic light-emitting diodes requires understanding charge transfer mechanisms across different length and time scales. The underlying electron transfer mechanisms can be efficiently explored using semiempirical quantum mechanical (SQM) methods. The dimer projection (DIPRO) method combined with the recently introduced non-self-consistent density matrix tight-binding potential (PTB) [Grimme et al., J. Chem. Phys. 158, 124111 (2023)] is used in this study to evaluate charge transfer integrals important for understanding charge transport mechanisms. PTB, parameterized for the entire Periodic Table up to Z = 86, incorporates approximate non-local exchange, allowing for efficient and accurate calculations for large hetero-organic compounds. Benchmarking against established databases, such as Blumberger's HAB sets, or our newly introduced JAB69 set and comparing with high-level reference data from ωB97X-D4 calculations confirm that DIPRO@PTB consistently performs well among the tested SQM approaches for calculating coupling integrals. DIPRO@PTB yields reasonably accurate results at low computational cost, making it suitable for screening purposes and applications to large systems, such as metal-organic frameworks and cyanine-based molecular aggregates further discussed in this work. [ABSTRACT FROM AUTHOR]

Despite major advances in efficiency, the operational stability of organic photovoltaic (OPV) devices remains poor. Therefore, understanding the degradation mechanisms and identifying potential solutions to improve device stability is critical to enabling the widespread commercialization of OPVs. Herein, simple filtration of the PBDB‐T:ITIC photoactive layer (PAL) solution prior to film deposition is demonstrated to enhance OPV device operational stability without compromising initial device performance. The effect of filtration, a commonly used but poorly understood OPV fabrication step, is investigated using a range of chemical, structural, and optoelectronic methods, on solutions and films. Filtration is found to remove large aggregates from solution without disrupting nanoscale preaggregation, resulting in enhanced acceptor ordering in PBDB‐T:ITIC thin films, significantly improving morphological stability and photostability. This simple and facile method is confirmed to be a general strategy that also works for other PBDB‐T‐containing OPV blends, including Y6‐based systems, and highlights how subtle changes in morphology can result in dramatic differences in operational stability. [ABSTRACT FROM AUTHOR]

Exciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free‐charge carriers, and is known to be an important parameter in determining the performance of organic opto‐electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star‐shaped π‐conjugated compounds DBC‐RD and TPE‐RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC‐RD and TPE‐RD, indicating that these molecules possess similar properties on a single‐molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC‐RD had a smaller Eb value of 0.24 eV compared with that of TPE‐RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC‐RD in pristine film is induced by molecular aggregation. By comparison with TPE‐RD, DBC‐RD showed superior performances in single‐component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films. [ABSTRACT FROM AUTHOR]

Organic semiconductors are used in organic opto‐electronic devices because of their various advantages. However, they are vulnerable to moisture and oxygen. Thus, flexible and transparent encapsulations with barrier properties against moisture and oxygen need to be developed to fabricate bendable and foldable organic semiconductor devices. In this study, a simple and highly productive self‐assembly process is developed from montmorillonites by using maximized Marangoni forces and a co‐solvent in an aqueous water and a non‐aqueous N‐methyl‐2‐pyrrolidone medium for the fabrication of a flexible and transparent encapsulation film. Water vapor transmission rate (WVTR) and optical transmittance of montmorillonite‐based flexible and transparent encapsulation films are modulated using different precursor solution concentrations and numbers of stacked montmorillonite layers. Long‐term stability of transparent polymer solar cells with self‐assembled flexible and transparent encapsulation films (WVTR of 6.66 × 10−3 g m−2 day−1 and optical transmittance of 90.5% at 550 nm) is enhanced, and performance of flexible polymer light‐emitting diodes with flexible encapsulation films is maintained after 1000 bending cycles, even at a bending radius of 2 mm. Mechanical properties of prepared encapsulation films are analyzed by conducting tensile tests and finite element analysis simulations, demonstrating that an integrated analysis includes both devices and encapsulation films. [ABSTRACT FROM AUTHOR]

Developing novel n‐type organic semiconductors is an on‐going research endeavour, given their pivotal roles in organic electronics and their relative scarcity compared to p‐type counterparts. In this study, a new strategy was employed to synthesize n‐type organic semiconductors featuring a fully fused conjugated backbone. By attaching two sets of adjacent amino and formyl groups to the indacenodithiophene‐based central cores and triggering a tandem reaction sequence of a Knoevenagel condensation‐intramolecular cyclization, DFA1 and DFA2 were realized. The solution‐processed organic field effect transistors based on DFA1 exhibited unipolar n‐type transport character with a decent electron mobility of ca. 0.10 cm2 V−1 s−1 (ca. 0.038 cm2 V−1 s−1 for DFA2 based devices). When employing DFA1 as a third component in organic solar cells, a high power conversion efficiency of 19.2 % can be achieved in ternary devices fabricated with PM6 : L8‐BO : DFA1. This work provides a new pathway in the molecular engineering of n‐type organic semiconductors, propelling relevant research forward. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) are gaining attention in building‐integrated and agricultural photovoltaics due to their light weight, mechanical flexibility, and low‐cost solution processability. To achieve commercial viability, understanding the relationships between active layer material structure, film morphology, and photovoltaic performance is crucial. Nanoscale infrared spectroscopy coupled with atomic force microscopy (nanoIR‐AFM) offers an advanced characterization of active layer morphology at high resolution to help understand OSC performance. This review outlines recent developments and applications of nanoIR‐AFM in OSC research, detailing its principles, instruments, and functions. Strategies to enhance OSC performance and their morphological characterization by nanoIR‐AFM are discussed, offering insights into active layer evolution and device performance. The review highlights challenges faced by nanoIR‐AFM in OSC applications and highlights its potential role in advancing OSC technology. As nanoIR‐AFM continues to evolve, it will play a critical role in OSC development, providing essential technical means for further progress. [ABSTRACT FROM AUTHOR]

A crucial challenge in the development of semi‐transparent solar cells is to maintain a reasonable power conversion efficiency (PCE) while reaching a high average visible transparency (AVT). Typically, organic semiconductors are favorable for this application since they can selectively absorb infrared light while transmitting visible light. This ability stems from limited electronic states at high(er) energies in contrast to inorganic semiconductors with their typical rise of the absorption coefficient toward higher photon energies. To increase PCE at high AVTs, a series of infrared dielectric Bragg reflectors is developed for semi‐transparent organic solar cells. Using the multi‐layered back electrode (TiO2|SiN|TiO2|AZO|Ag|AZO) with PV‐X Plus as photoactive layer and a metal‐free PEDOT:PSS top electrode, a light utilization efficiency (LUE = AVT × PCE) of up to 4.32% is achieved, together with an AVT of 47.9%. Although the short circuit current and AVT agree well with optical simulations, a low fill factor (FF) and partial shunting limit the overall device performance. Using ZnO and PFN‐Br as additional electron transport layers and modifying the back electrode stack (TiO2|SiO2|TiO2|AZO|Ag|AZO) accordingly leads to an LUE of up to 4.6% with a remarkable AVT of 51.9% and a maximum PCE of 8.79%. [ABSTRACT FROM AUTHOR]

Cyanation is a common chemical modification strategy to fine‐tune the energy levels and molecular packing of organic semiconductors, especially materials used in organic solar cells (OSCs). Generally, cyanation is used to modify the end groups of high‐performance small‐molecule acceptors (SMAs). However, the cyanation strategy has not been investigated on the central backbone of SMAs, which could introduce stronger intermolecular interaction and enhance the π–π stacking for rapid charge transport. This paper, for the first time, reports a new cyanation strategy on the central benzo‐quinoxaline core and synthesizes two novel A‐DA'D‐A type SMAs, named BQx‐CN and BQx‐2CN, with mono‐ and di‐cyanide groups, respectively. Through tailoring the number of CN groups, the BQx‐CN‐based OSC exhibits the best device performance of 18.8%, which is significantly higher than the non‐cyano BQx‐based one. The reason for the superior performance of BQx‐CN‐based devices can be attributed to the fine‐tuned energy level, stronger packing, and ideal phase segregation, which lead to superior exciton dissociation, faster charge transport, and suppressed recombination, therefore the highest fill factor (FF) and power conversion efficiencies (PCE). The research demonstrates the effectiveness of the cyanation strategy on the central core of SMAs for enhanced molecular packing and better performance of OSCs. [ABSTRACT FROM AUTHOR]

The design principles of acceptor1–acceptor2 copolymers featuring alternating diketopyrrolopyrrole (DPP) and thienopyrrolodione (TPD) moieties are investigated. The investigated series of polymers is obtained by varying the aromatic linker between the two acceptor motifs between thiophene, thiazole, pyridine, and benzene. High electron affinities between 3.96 and 4.42 eV, facilitated by the synergy of the acceptor motifs are determined with optical gaps between 1.37 and 2.02 eV. Grazing incidence wide‐angle X‐ray scattering studies reveal a range of film morphologies after thermal annealing, including face‐on, end‐on and superstructure edge‐on‐like crystallites. Conversely, all materials form thin edge‐on layers on the polymer–air interface, as demonstrated by multi‐elemental near‐edge X‐ray absorption fine‐structure spectroscopy. The benefit of the electron‐deficient linkers thiazole and pyridine is evident: In organic field effect transistors, electron mobilities of up to 4.6 × 10−2 cm2 V−1 s−1 are obtained with outstanding on/off current ratios of 5 × 105, facilitated by the absence of detectable hole transport in these materials. Viability for all‐polymer solar cells is assessed in active layer blends with the donor polymer PM6, yielding a maximum average power conversion efficiency of 4.8% and an open circuit voltage above 1 V. [ABSTRACT FROM AUTHOR]

Organic small molecules have been proven to be the most efficient and predominantly employed hole transport layers (HTLs) in perovskite solar cells (PSCs), the reliance of HTLs on additives like Li‐TFSI has been unavoidable, particularly in terms of the well‐known Spiro‐OMeTAD. However, Li‐TFSI aggregation in HTL results in the decreased performance and stability of PSCs with serious hysteresis. It is an urgent need to explore a universal strategy to solve Li‐TFSI‐induced issues. Herein, a pyrene‐based organic semiconductor (PC) as an effective and universal additive for HTL application is developed. It is found that the introduction of PC can efficiently improve the hot carriers extraction/transfer and reduce the charge recombination in the device. Consequently, PSCs based on Spiro‐OMeTAD+PC as a HTL exhibit an excellent PCE of 24.80% with a negligible hysteresis, much higher than the control device (22.14%). Additionally, the efficiency of the PC incorporated into another well‐known X60 HTL‐treated device is enhanced to 24.12% from the control device (22.04%), confirming its universal application in PSCs. Moreover, PC can effectively suppress the Li+ aggregation in HTL, and the unencapsulated PSCs exhibit high stability. The findings in this work provide an effective and universal avenue to construct highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

The fabrication of the flexible devices with excellent photovoltaic performance and stability is critical for the commercialization of organic solar cells (OSCs). Herein, the conjugated dimer acceptor DY‐TVCl and the non‐conjugated dimer acceptor DY‐3T based on the monomer MY‐BO are synthesized to regulate the molecular glass transition temperatures (Tg) for improving the morphology stability of active layer films. And the crack onset strain values for the blend films based on dimer acceptors are superior than that of small molecule, which are beneficial for the preparation of flexible devices. Accordingly, the binary device based on PM6:DY‐TVCl achieves a maximum power conversion efficiency (PCE) of 18.01%. Meanwhile, the extrapolated T80 (time to reach 80% of initial PCE) lifetimes of the PM6:DY‐TVCl‐based device and PM6:DY‐3T‐based device are 3091 and 2227 h under 1‐sun illumination, respectively, which are better than that of the PM6:MY‐BO‐based device (809 h). Furthermore, the flexible devices based on DY‐TVCl and DY‐3T exhibit the efficiencies of 15.23% and 14.34%, respectively. This work affords a valid approach to improve the stability and mechanical robustness of OSCs, as well as ensuring the reproducibility of organic semiconductors during mass production. [ABSTRACT FROM AUTHOR]

The achievement of high performance in organic solar cells (OSCs) is highly dependent on efficient exciton dissociation. However, a comprehensive understanding of the exciton dissociation process under photoexcitation in OSCs remains elusive. Herein, a prototypical system of PM6:Y6 is adopted to explore the exciton dissociation process. An organic semiconductor PCz with distinctive photoexcitation signals from PM6 and Y6 is incorporated as the third component. Femtosecond transient absorption spectroscopy demonstrates clear cascade charge transfer processes in ternary PM6:PCz:Y6 system. These cascade channels contribute to enhancing the efficiency of exciton dissociation. Consequently, the nonradiative recombination energy loss is reduced, resulting in an improved power conversion efficiency (PCE) of OSCs. Furthermore, the reduction of energy loss is verified in different OSCs. When PCz is introduced into the D18:L8‐BO system, a low nonradiative recombination energy loss of 0.175 eV is demonstrated, contributing a PCE of over 19%. This work highlights that the insight of efficient exciton dissociation enables low nonradiative recombination losses for efficient OSCs. [ABSTRACT FROM AUTHOR]

The interfacial layers of organic optoelectronic devices generally suffer from the problems of difficulty in regulating the work function (WF) and low mobility, which are prone to mismatch of interfacial energy levels and loss of carrier transport energy. Herein, O‐terminated and NH2‐terminated Ti3C2Tx MXenes quantum dots (MQDs) are synthesized to develop efficient O‐MQD hole transfer layer (HTL) and E‐MQD electron transfer layer (ETL) for organic optoelectronic devices of organic solar cells (OSCs) and organic photodetectors (OPDs). It is found that the strong electronic coupling interaction between the surface terminations and matrices enables O‐MQD and E‐MQD with tunable WF and satisfactory conductivity. Consequently, in a binary D18:L8‐BO system, the power conversion efficiencies of the OSC device based on O‐MQD HTL and E‐MQD ETL are 18.62% and 18.15%, respectively. Moreover, the OPDs with O‐MQD HTL and E‐MQD ETL exhibit higher shot‐noise‐limited detectivity (Dshot*) of 1.24 × 1013 and 1.10 × 1013 Jones, respectively, compared to the devices using classic interlayers. These findings provide some insights into the design of advanced dual‐function interlayers for organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

Charge transport in the active layer, which can be effectively modulated by molecular doping of organic semiconductors, significantly affects the photovoltaic performance of organic solar cells (OSCs). However, it is difficult to control the dopant distribution in the bulk heterojunction (BHJ) films, which hinders efficient doping in OSCs. Herein, an effective n‐doping strategy is developed via sequential deposition (SD) of D18 donor and doped acceptor. The favorable vertical component distribution in SD films helps to optimize carrier transport pathways. The SD method confines the n‐dopant N‐DMBI to the acceptor layer, allowing positive effects of molecular doping. Consequently, the doped SD device exhibits superior charge transport with suppressed charge recombination, lower trap density, and enhanced charge extraction compared to the undoped one, resulting in a high power conversion efficiency of 19.55% for D18/L8‐BO binary OSCs. In addition, the doping does not affect the thermal stability of the devices, with the doped SD device retaining over 90% of its initial efficiency after 1200 h of heating at 80 °C. The universality of the SD doping method is also verified in other non‐fullerene acceptor systems. These results demonstrate the great potential of SD doping strategy for building high‐performance OSCs with enhanced charge transport. [ABSTRACT FROM AUTHOR]

In the field of organic solar cells, organic semiconductors with Y6‐based chemical structure and their corresponding quinoxaline‐based assemblies are settled down as promising materials in the field of OSCs. However, the chemical structure of Y6 derivatives does not allow an expansion in the electron‐withdrawing central core, in contrast to their quinoxaline‐based analogues. For this reason, herein, two different quinoxaline‐based A–D–A′–D–A derivatives with 2D π‐extended cores endowed with electroactive rylenimide moieties, named as Y6‐1Napht and Y6‐1Pery, are designed and synthesized. These enlarged fused‐ring electron acceptors (FREAs) allow to study the influence of the length of the ryleneimide moiety on its structural, optical, electrochemical, and thermal properties as well as the tailoring of the frontier molecular orbitals. These results are also supported by quantum chemical calculations and photoluminescence measurements that provide additional information about their thermal stability and the microstructure of the films. Finally, as a proof of concept and to study the influence of these chemical modifications on the central core, solar cells based on these π‐conjugated nonfullerene acceptors are fabricated. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskite semiconductors have revolutionized next‐generation photovoltaics (PV) due to several characteristics such as solution‐processability, gap tunability, and excellent charge generation and transport properties. This has made them very adaptable for various applications in light harvesting and photodetection. One such rapidly growing application is indoor photovoltaics (IPV) which have the potential to power standalone Internet of Things devices. IPV requires wider optimal bandgaps than solar cells (1.8 vs 1.3 eV) due to the differences between the spectra of artificial lights versus solar radiation. For IPV applications, the active layer wide‐gap perovskite must be developed systemically considering all other components of the device, such as interlayers, electrodes, and scaling. This perspective provides an overview of the potential and challenges facing perovskite‐based IPV from a theoretical, material, and experimental perspective. Furthermore, accurate characterization of perovskite IPVs under simulated indoor conditions is discussed and candidate perovskite PV (PPV) systems are presented to provide insight into IPV development. These include IPV‐optimized formamidinium cesium‐based perovskite, wide‐gap p‐i‐n devices, and 2D perovskite devices, tested under spectrophotometrically calibrated LED illumination at various indoor‐relevant illuminances and benchmarked against thermodynamic predictions. Finally, strategies required to create stable, optimized PPV devices for indoor applications are discussed. [ABSTRACT FROM AUTHOR]

Organic photovoltaics (OPV) present a promising thin-film solar cell technology with particular benefits in terms of weight, aesthetics, transparency, and cost. However, despite being studied intensively since the mid 90's, OPV has not entered the mass consumer market yet. Although the efficiency gap with other thin-film photovoltaics has largely been overcome, active layer stability and performance reproducibility issues have not been fully resolved. State-of-the-art OPV devices employ a physical mixture of electron donor and acceptor molecules in a bulk heterojunction active layer. These blends are prone to morphological changes, leading to performance losses over time. On the other hand, in "single-component" organic solar cells, the donor and acceptor constituents are chemically connected within a single material, preventing demixing and thereby enhancing device stability. Novel single-component materials affording reasonably high solar cell efficiencies and improved lifetimes have recently emerged. In particular, the combination of donor and acceptor structures in conjugated block copolymers (CBCs) presents an exciting approach. Nevertheless, the current CBCs are poorly defined from a structural point of view, while synthetic protocols remain unoptimized. More controlled synthesis followed by proper structural analysis of CBCs is, however, essential to develop rational structure-property-device relations and to drive the field forward. In this perspective, we provide a short overview of the state-of-the-art in single- component organic solar cells prepared from CBCs, reflect on their troublesome characterization and the importance of chemical precision in these structures, give some recommendations, and discuss the potential impact of these aspects on the field. [ABSTRACT FROM AUTHOR]

Hygroscopic and acidic nature of organic hole transport layers (HTLs) insisted to replace it with metal oxide semiconductors due to their favorable charge carrier transport with long chemical stability. Apart from large direct bandgap and high optical transmittance, ionization energy in the range of −5.0 to −5.4 eV leads to use NiO as HTL due to good energetic matching with lead halide perovskites. Analyzing X-ray photoelectron spectroscopic (XPS) data of NiO, it is speculated that p-type conductivity is related to the NiOOH or Ni2O3 states in the structure and the electrical conductivity can be modified by altering the concentration of nickel or oxygen vacancies. However, it is difficult to separate the contribution from nonlocal screening, surface effect and the presence of vacancy induced Ni3+ ion due to very strong satellite structure in the Ni 2p XPS spectrum of NiO. Thus, an effective approach to analyze the NiO XPS spectrum is presented and the way to correlate the presence of Ni3+ with the conductivity results which will help to avoid overestimation in finding the oxygen-rich/deficient conditions in NiO. [ABSTRACT FROM AUTHOR]

In the development of high‐performance organic solar cells (OSCs), the self‐organization of organic semiconductors plays a crucial role. This study focuses on the precisely manipulation of molecular assemble via tuning alkyl side‐chain topology in a series of low‐cost nonfused‐ring electron acceptors (NFREAs). Among the three NFREAs investigated, DPA‐4, which possesses an asymmetric alkyl side‐chain length, exhibits a tight packing in the crystal and high crystallinity in the film, contributing to improved electron mobility and favorable film morphology for DPA‐4. As a result, the OSC device based on DPA‐4 achieves an excellent power conversion efficiency of 16.67 %, ranking among the highest efficiencies for NFREA‐based OSCs. [ABSTRACT FROM AUTHOR]

The uncoordinated lead cations are ubiquitous in perovskite films and severely affect the efficiency and stability of perovskite solar cells (PSCs). In this work, 15‐crown‐5 with various heteroatoms are connected to the organic semiconductor carbazole diphenylamine, and two new compounds, CDT‐S and CDT‐N, are developed to modify the Pb2+ defects in perovskite films through the anti‐solvent method. Apart from the oxygen atoms, there are also N atoms on crown ether ring in CDT‐N, and both S and N heteroatoms in CDT‐S. The heteroatoms enhance the interaction between the crown ether‐based semiconductors and the undercoordinated Pb2+ defect in perovskite. Particularly, the stronger interaction between S atoms and Pb2+ further enhances the defect passivation effect of CDT‐S than CDT‐N, thereby more effectively suppressing the non‐radiative recombination of charge carriers. Finally, the efficiency of the device treated with CDT‐S is up to 23.05 %. Moreover, the unencapsulated device based on CDT‐S maintained 90.5 % of the initial efficiency after being stored under dark conditions for 1000 hours, demonstrating good long‐term stability. Our work demonstrates that crown ethers are promising in perovskite solar cells, and the crown ether containing multiple heteroatoms could effectively improve both efficiency and stability of devices. [ABSTRACT FROM AUTHOR]

The limited exciton lifetime (τ, generally <1 ns) leads to short exciton diffusion length (LD) of organic semiconductors, which is the bottleneck issue impeding the further improvement of power conversion efficiencies (PCEs) for organic solar cells (OSCs). However, efficient strategies to prolong intrinsic τ are rare and vague. Herein, we propose a facile method to efficiently reduce vibrational frequency of molecular skeleton and suppress exciton‐vibration coupling to decrease non‐radiative decay rate and thus prolong τ via deuterating nonfullerene acceptors. The τ remarkably increases from 0.90 ns (non‐deuterated L8‐BO) to 1.35 ns (deuterated L8‐BO‐D), which is the record for organic photovoltaic materials. Besides, the inhibited molecular vibration improves molecular planarity of L8‐BO‐D for enhanced exciton diffusion coefficient. Consequently, the LD increases from 7.9 nm (L8‐BO) to 10.7 nm (L8‐BO‐D). The prolonged LD of L8‐BO‐D enables PM6 : L8‐BO‐D‐based bulk heterojunction OSCs to acquire higher PCEs of 18.5 % with more efficient exciton dissociation and weaker charge carrier recombination than PM6 : L8‐BO‐based counterparts. Moreover, benefiting from the prolonged LD, D18/L8‐BO‐D‐based pseudo‐planar heterojunction OSCs achieve an impressive PCE of 19.3 %, which is among the highest values. This work provides an efficient strategy to increase the τ and thus LD of organic semiconductors, boosting PCEs of OSCs. [ABSTRACT FROM AUTHOR]

The fine structural–functional construction of organic semiconductor materials provides an abundant candidate store for the hole‐transport materials (HTMs) in perovskite solar cells (PSCs). Whereas, challenges remain in unveiling the clews behind the molecular conformation engineering and desired properties realizing for efficient HTMs. In this work, a couple of simple organic diphenylfluorene‐cored isomers (FH27 and FH99) with different spatial integration strategies of molecular conformation are judiciously devised as HTMs in the PSCs. The theoretical simulation and experimental analyses decipher that the excellent electronic/energetic distribution, intermolecular stacking geometry, intrinsic solid‐crystal film morphology, and charge‐extraction‐transport ability are demonstrated for FH27, ascribing to its harmonious intersectional couplings for the planar/orthogonal molecular conformation. The FH27‐based device achieves a high efficiency of 23.61% with benign life span, both superior to the FH99‐based device. [ABSTRACT FROM AUTHOR]

Anode interlayers play critical roles in organic solar cells, impacting the electrode's work function, energy level alignment, hole extraction, and electrode surfaces. However, the development of the commonly used anode interlayer PEDOT:PSS lags behind the rapid development of organic solar cells due to its low conductivity, acidity, and poor electron‐blocking capabilities. Herein, an innovative strategy is proposed to regulate the intrinsic properties of PEDOT:PSS by incorporating molybdenum‐containing semiconductors (MoO3, MoS2), which is validated using the state‐of‐the‐art active layer consisting of PM6:Y6 in conventional devices. The addition of molybdenum‐containing semiconductors alters the aggregation morphology of the PEDOT:PSS layer, increasing its conductivity and reducing its acidity. Furthermore, the hole extraction and electron‐blocking ability are improved by changing the work function of the anode with the influence of the deep energy level and by forming a trap energy level to capture electrons. Consequently, when the interlayer is employed, a champion power conversion efficiency of 17.1% in the PM6:Y6 devices and 18.9% in organic solar cells composed of PM6:L8‐BO is achieved. The results, which enhance the intrinsic properties of PEDOT:PSS with molybdenum‐containing semiconductors, offer valuable guidelines for engineering anode interlayers to fabricate highly efficient non‐fullerene organic solar cells. [ABSTRACT FROM AUTHOR]

In recent years, organic semiconductors have been widely developed to improve the power conversion efficiencies (PCEs) of organic solar cells (OSCs) and organic photoelectrochemical (PEC) devices. Although the PCEs of organic devices is relatively high, the stability and changes of electronic properties of organic semiconductors in long time working are still lack of intensive study. PEC devices are soaked in electrolyte which can diffuse into the devices via the hydrophilia buffer layer (PEDOT: PSS for example) or through the fractures in protection layer caused by the mechanical stresses. The synergistic effects of electrolyte with illumination and aggregation of photo-generated electrons on organic semiconductors are special and still not well established. Herein, the stability and electronic properties changes of organic light absorption layer was directly evaluated after long-term operation in electrolyte under different illumination and bias (controlling the photo-induced electrons aggregation). The photocharging effect of organic bulk heterojunction (BHJ) was observed and the influence factors were studied through electrochemical measurements. The variations of electrical characters of organic light absorption layer such as RS, CSC, RT, CSS, RCT after long-term operations were investigated and the corresponding influence factors were speculated from electrochemical impedance spectroscopy (EIS). That will give us a deeper understand of the degradation mechanisms of organic semiconductors in electrolyte and an inspiration for the future stability research of fullerene or popular non-fullerene semiconductors. [ABSTRACT FROM AUTHOR]

The rapid development of photovoltaic technology has driven the search for novel materials that can improve the cost-effectiveness and efficiency of solar cells. Organic semiconductors offer unique optical tunability and transparency, allowing customization for the absorption of specific optical spectra like near-infrared radiation. Through the molecular engineering of electron donors and acceptors, these materials can be optimized for targeted optical selectivity. This adaptability enables the development of efficient energy-harvesting devices tailored for specific spectral regions. Consequently, organic semiconductors present a promising avenue for specialized applications such as semi-transparent organic solar cells. This review offers a detailed summary of the latest developments in novel organic semiconductor materials, focusing on design principles and synthesis of materials in the context of semi-transparent organic solar cells. Optimization of molecular architecture, photovoltaic performance, and the optoelectronic properties of these materials has been explored, highlighting their potential for next-generation solar energy conversion. [ABSTRACT FROM AUTHOR]

The high trap density (generally 1016–1018 cm−3) in organic solar cells (OSCs) brings about the localization of charge carriers and reduced charge carrier lifetime, mainly due to the weak intermolecular interactions of organic semiconductors resulting in their relatively poor crystallinity, which leads to low charge carrier mobilities and intense non-radiative recombination, thus impeding the further improvement of power conversion efficiencies (PCEs). Therefore, trap suppression is crucial to boost the performance of OSCs, and improving the crystallinity of donor/acceptor materials and enhancing the molecular order in devices can contribute to the trap suppression in OSCs. In this feature article, we summarize the recent advances of trap suppression in OSCs by material design and device engineering, and further outline possible development directions for trap suppression to enhance PCEs of OSCs. [ABSTRACT FROM AUTHOR]

Replacing the traditional CdS buffer layer with more environmentally friendly materials is an urgent issue for environment‐friendly CZTSSe solar cells. Herein, a nontoxic, flexible, and conductive organic molecular semiconductor PCBM to replace CdS is used and a Cd‐free CZTSSe solar cell is obtained. By introducing mild spin‐coated ZnO window layers, the damage of PCBM in conventional sputtering ZnO process is effectively avoided, and a higher efficiency than previously reported organic semiconductor buffer layer systems and comparable to CdS buffer layer devices are achieved. The flexible PCBM covers the surface of the CZTSSe absorber layer densely and forms a flatter film surface, which is beneficial for the following ZnO deposition. The CZTSSe/PCBM interface exhibits a typical "spike‐like" energy band alignment with a conduction band offset value of only 0.1 eV. Compared with CZTSSe/CdS interface, the CZTSSe/PCBM heterojunction possesses larger interfacial recombination resistance and a longer carrier lifetime. The ideal coating ability, suitable energy band alignment, as well as the better interface carriers transfer behavior suggest that the organic molecular semiconductors can be used instead of the CdS buffer layer to pave the way for truly environment‐friendly kesterite photovoltaic devices. [ABSTRACT FROM AUTHOR]

Organic semiconductors with noncovalently conformational locks (OSNCs) are promising building blocks for hole‐transporting materials (HTMs). However, lack of satisfied neighboring building blocks negatively impacts the optoelectronic properties of OSNCs‐based HTMs and imperils the stability of perovskite solar cells (PSCs). To address this limitation, we introduce the benzothieno[3,2‐b]thiophene (BTT) to construct a new OSNC, and the resulting HTM ZS13 shows improved intermolecular charge extraction/transport properties, proper energy level, efficient surface passivation effect. Consequently, the champion devices based on doped ZS13 yield an efficiency of 24.39 % and 20.95 % for aperture areas of 0.1 and 1.01 cm2, respectively. Furthermore, ZS13 shows good thermal stability and the capability of inhibiting I− ion migration, thus, leading to enhanced device stability. The success in neighboring‐group engineering can triggered a strong interest in developing thienoacene‐based OSNCs toward efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Critical point parabolic band (CPPB) oscillators are often useful to model the optical response of semiconductor materials, such as hybrid organic–inorganic lead halide-based perovskites, to incident photons in the form of the complex dielectric function (ε = ε 1 + i ε 2) spectra. Some models of ε using CPPB oscillators are not guaranteed Kramers–Kronig (KK) consistent (and therefore not physically realistic), may have excess or arbitrary parameter values, or may require prohibitively long computational time when used to fit ellipsometric spectra. For excitonic CPPBs, commonly used to describe the optical response of hybrid organic–inorganic lead halide-based perovskite materials, a physically realistic, parametric model of ε is developed from the KK relationship between ε 1 and ε 2 for a number of CPPB oscillators with an Urbach tail below the lowest direct transition. This parametric model is shown to produce the same line shape reported from previous works accurately and more quickly than other available KK-consistent CPPB models. [ABSTRACT FROM AUTHOR]

The article offers information on the advancements in perovskite solar cells (PSCs), emphasizing their efficiency improvements over the past decade. Topics include the exploration of various strategies to enhance the quality of the perovskite layer, such as using excess precursors, additives, or passivating agents.

Carrier-selective contacts based on inorganic materials (e.g., silicon layers and metal oxides) have been intensively investigated for efficient crystalline silicon (c-Si) photovoltaics. Compared to the vacuum deposition process for inorganic films, organic semiconductors offer a simplified and low-cost processing. Herein, solution-processed poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) is developed as hole-selective contact for c-Si solar cells. PTAA exhibits a suitable band alignment with p-type c-Si, featuring a small valence band offset (~0.1 eV) and a large conduction band offset (~2.2 eV) for effective electron blocking. PTAA combined with Al2O3 passivation interlayer is demonstrated to simultaneously offer a low contact resistivity (36.5mΩ cm¹) and a moderate surface passivation (implied open-circuit voltage 635.6 mV) on p-type c-Si surface. By the implementation of a full-area hole-selective Al2O3/PTAA rear contact, a champion efficiency of 20.2% is achieved on the hybrid c-Si solar cells. Herein, a guiding principle for future research on polymeric carrier-selective contact for c-Si solar cells is provided. [ABSTRACT FROM AUTHOR]

The conjugated organic semiconductor spacers have drawn wide attention in two‐dimensional (2D) perovskites and formamidinium (FA) has been widely used as A‐site cation in high‐performance 3D perovskite solar cells (PSCs). However, the FA‐based semiconductor spacers have rarely been investigated in 2D Ruddlesden‐Popper (RP) perovskites. Here, we developed two FA‐based spacers containing thieno[3,2‐b]thiophene (TT) and 2,2′‐bithiophene (BT) units, namely TTFA and BTFA, respectively, for 2D RP PSCs. The nucleation and crystallization kinetics of TTFA‐Pb and BTFA‐Pb from sol‐gel to film were investigated using in situ optical microscopy and in situ grazing incidence wide‐angle X‐ray scattering (GIWAXS) measurements. It is found that the TTFA spacer could reduce the energy barrier of nucleation and induces crystal vertical orientation of 2D perovskite by forming larger clusters in precursor solution, resulting in much improved film quality. Benefiting from the enlarged crystal grains, reduced exciton binding energy, and decreased electron‐phonon coupling coefficient, the photovoltaic device based on (TTFA)2MAn−1PbnI3n+1 (n=5) achieved a champion efficiency of 19.41 %, which is a record for 2D RP PSCs with FA‐based spacers. Our work provides deep understanding of the nucleation and crystallization process of 2D RP perovskite films and highlights the great potential of FA‐based semiconductor spacers in highly efficient 2D PSCs. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) are a promising photovoltaic technology that employs organic semiconductor material as the photoactive layer, which has the unique advantages of light weight, large‐area flexible fabrication, low‐cost, and semitransparent. In recent years, the performance of OSCs has been significantly improved, and the highest power conversion efficiency has exceeded 19%. Despite the tremendous progress in OSCs, the major bottleneck in realizing the commercialization of OSCs is the device stability. Therefore, reviewing the recent research progress on the stability of high‐performance OSCs is urgent and necessary. This review discusses the factors limiting device lifetime, such as metastable morphology, air, irradiation, heat, and mechanical stresses. Additionally, this review presents the research progress over the last 5 years, focusing on enhancing device stability from the perspective of photoactive layers and other functional layers, which includes material design and device engineering, such as solid additives, device fabrication, optimizing buffer layers, using stable electrodes, and encapsulation. Lastly, this review explores current commercialization challenges and prospects, including using advanced machine learning techniques to assist experimental research. [ABSTRACT FROM AUTHOR]

Two exotic 6‐cantilever small molecular platforms, characteristic of quite different molecular configurations of propeller and quasi‐plane, are established by extremely two‐dimensional conjugated extension. When applied in small molecular acceptors, the only two cases of CH25 and CH26 that could contain six terminals and such broad conjugated backbones have been afforded thus far, rendering featured absorptions, small reorganization and exciton binding energies. Moreover, their distinctive but completely different molecular geometries result in sharply contrasting nanoscale film morphologies. Finally, CH26 contributes to the best device efficiency of 15.41 % among acceptors with six terminals, demonstrating two pioneered yet highly promising 6‐cantilever molecular innovation platforms. [ABSTRACT FROM AUTHOR]

Organic photovoltaic semiconductors have made significant progress and have promising application prospects after decades of development. When compared with traditional semiconductors, the solution method for preparing photovoltaic semiconductors shows the advantages of low cost and convenient preparation. However, because of the extremely poor solubility of the polymers used to prepare semiconductors, toxic solvents must be used when using the solution method, which has significant negative effects on the environment and operators and severely limits its development prospects. Organic nanoparticles (NPs), on the other hand, can avoid these issues. Because NPs are typically water or alcohol-based, no toxic solvents are used. Furthermore, NPs have been used in organic solar cells, hydrogen catalysis, organic light-emitting diodes, and other fields after nearly two decades of development, and their preparation methods have been developed. We describe the preparation, optimization, and application of NPs in photovoltaic semiconductors in this review. [ABSTRACT FROM AUTHOR]

Fiber‐shaped organic solar cells (FOSCs) with intrinsic stretchability show great potential in stretchable and wearable electronics applications. However, limited by the poor stretchability of small molecule semiconductors, the stretchability of FOSCs is still not satisfied. Polymerized nonfullerene acceptors with excellent photovoltaic performance are a promising strategy for preparing stretchable semiconductors and photovoltaics. Herein, an efficient polymer‐based bulk‐heterojunction blend is adopted as the photoactive material of the stretchable all‐polymer FOSCs. The fabricated all‐polymer FOSCs show superior intrinsic stretchability that remains more than 90% of the initial efficiency under the stretch strain of 50% and maintains stable performance even when undergoing hundreds of stretching–releasing cycles. By adding the third component of polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene (SEBS) elastomer, the stretchable all‐polymer FOSCs can endure the ultrahigh stretch strains over 80%. This study demonstrates the superior mechanical properties of the all‐polymer FOSCs and the simple yet effective strategy of SEBS additive to enhance stretchability. [ABSTRACT FROM AUTHOR]

Doped hole (respectively electron) transport layers [HTLs (respectively ETLs)] are commonly used in evaporated organic devices to achieve high work function hole contact (respectively low work function electron contact) in organic LEDs to inject large current, in solar cells to increase the open circuit voltage, and in photodetectors to minimize the dark current. However, optimization of the HTL thickness results from a delicate trade-off. Indeed, on the one hand, to minimize the impact of HTLs on light propagation and series resistance effects, it is commonly admitted that HTLs must be kept as thin as possible. In this work, a model, validated by drift and diffusion simulations, has shown that, depending of the doping level, a minimum thickness between 10 and 20 nm was needed to prevent the transport layer work function from degradation due to field effects. Experiments have been performed on template p-only devices featuring a single HTL of various thicknesses and doping, confirming the validity of the model. Finally, simulations have been performed on a p-i-n device featuring both HTL and ETL. These results constitute precious indications for the design of efficient evaporated organic LEDs, solar cells, or photodetectors. [ABSTRACT FROM AUTHOR]

Perylene-3,4-(dicarboxylic monoimide)-9,10-(dicarboxylic monoanhydrate) (PIA) is one key intermediate to construct functionalized perylene diimides (PDIs) for various applications. However, the difficulty in synthesizing chlorinated PIA hinders the study of chlorinated PDI-based materials. Although chlorination has been widely used to modify the properties of organic semiconductors. We successfully synthesize chlorinated PIA via a simple hydrolysis reaction using LiOH as the base, then a PDI dimer connected at the imide position, N-di-PDI-4Cl, is synthesized as an application example of chlorinated PIA. The heavily chlorinated PDI dimer exhibits deeper energy levels, slightly blue-shifted UV-Vis absorption compared to the non-chlorinated analogue. In addition, the photovoltaic performance of N-di-PDI-4Cl is characterized. This study paves one easy way to synthesize chlorinated PIA and its more delicate derivatives. [ABSTRACT FROM AUTHOR]

Computer science implements algorithms and techniques to automate problem-solving solutions. Due to the chemical versatility of organic building blocks, many organic semiconductors have been utilized for organic solar cells (OSCs). The computational methods can potentially drive experimentalists to discover and design high-performance materials. OSCs' objective is the performance of their energy conversion efficiency and stability. One idea that has improved efficiency and stability is that of ternary systems, known as ternary organic solar cells (TOSCs). The photoactive layer in TOSCs is formed by mixing three distinct components together. This review is about the employment of computational approaches for investigating TOSCs. Here, we outlined the basics of computational methods and standard application procedures. This article offers a concise overview of various computational algorithms, relevant software, and tools. Additionally, it examines the present state of research regarding computations in TOSCs. The challenges associated with TOSCs, including intricacy metrics, diverse chemical structures, and programming skills, are discussed. Furthermore, we suggest some ways to improve the utility of computation in TOSCs research enterprises. [ABSTRACT FROM AUTHOR]

Semitransparent organic solar cells (STOSCs) exhibit promising application as power‐generating windows in buildings and agricultural greenhouses. Due to unique optical properties of organic semiconductors, they can efficiently absorb near‐infrared light while maintaining a high degree semitransparency in the visible range. Since power conversion efficiency (PCE) and average visible transmission (AVT) frequently stand in a trade‐off relationship, a major challenge in improving the overall performance of STOSCs is maximizing the product of both, called light utilization efficiency (AVT × PCE = LUE). Herein, using multiple layers of aluminium‐doped ZnO (AZO) and silver as an infrared reflecting back electrode, in order to increase current generation while maintaining high visible transparency, is proposed. Using optical modeling, the optimal layer thickness of the AZO layer sandwiched between two Ag layers is determined, leading to an increased photocurrent generation of up to 10%. Simultaneously, experimental findings show that the fill factor decreases with an increasing AZO layer thickness. By adjusting the thickness of the photoactive layer, the blend concentration, and improving the top electrode material the thus‐far highest reported LUE for indium tin oxide‐free STOSCs is attained, reaching 4.0% with a PCE of 8.7% and an AVT of 46.3%. [ABSTRACT FROM AUTHOR]

To understand the limitations placed on the open‐circuit voltage of bulk heterojunction (BHJ) organic solar cells, the energy levels of neat donor and acceptor samples are often characterized and applied to study BHJ blends. However, energy levels derived from neat samples may not necessarily reflect those at the donor:acceptor interface in blends. The properties of organic semiconductors are sensitive to microstructural changes, with non‐fullerene acceptors (NFAs) in particular known to exhibit different thin‐film polymorphs. To investigate the influence of differences in molecular packing in neat and blend films, temperature‐dependent current–voltage characteristics are measured for bilayer (BL) and BHJ devices. Herein, the fullerene acceptor PC71BM is compared—whose energy levels are expected to be less sensitive to molecular packing—with the NFA ITIC, paired with the same donor polymer PTB7‐Th. It is found that the interfacial energy levels differ for BL and BHJ devices for the PTB7‐Th:ITIC system but remain the same for the PTB7‐Th:PC71BM system. Furthermore, X‐ray scattering measurements identify that ITIC exhibits a different packing mode in neat films and in BHJ blends. Such microstructure‐dependent differences between neat and blend samples need to be considered when studying energy losses in NFA BHJ solar cells. [ABSTRACT FROM AUTHOR]

Due to the intrinsically flexible molecular skeletons and loose aggregations, organic semiconductors, like small molecular acceptors (SMAs) in organic solar cells (OSCs), greatly suffer from larger structural/packing disorders and weaker intermolecular interactions comparing to their inorganic counterparts, further leading to hindered exciton diffusion/dissociation and charge carrier migration in resulting OSCs. To overcome this challenge, complete peripheral fluorination was performed on basis of a two‐dimensional (2D) conjugation extended molecular platform of CH‐series SMAs, rendering an acceptor of CH8F with eight fluorine atoms surrounding the molecular backbone. Benefitting from the broad 2D backbone, more importantly, strengthened fluorine‐induced secondary interactions, CH8F and its D18 blends afford much enhanced and more ordered molecular packings accompanying with enlarged dielectric constants, reduced exciton binding energies and more obvious fibrillary networks comparing to CH6F controls. Consequently, D18:CH8F‐based OSCs reached an excellent efficiency of 18.80 %, much better than that of 17.91 % for CH6F‐based ones. More excitingly, by employing D18‐Cl that possesses a highly similar structure to D18 as a third component, the highest efficiency of 19.28 % for CH‐series SMAs‐based OSCs has been achieved so far. Our work demonstrates the dramatical structural multiformity of CH‐series SMAs, meanwhile, their high potential for constructing record‐breaking OSCs through peripheral fine‐tuning. [ABSTRACT FROM AUTHOR]

Organic photovoltaics have attracted worldwide interest due to their unique advantages in developing low-cost, lightweight, and flexible power sources. Functional molecular design and synthesis have been put forward to accelerate the discovery of ideal organic semiconductors. However, it is extremely expensive to conduct experimental screening of the wide organic compound space. Here we develop a framework by combining a deep learning model (graph neural network) and an ensemble learning model (Light Gradient Boosting Machine), which enables rapid and accurate screening of organic photovoltaic molecules. This framework establishes the relationship between molecular structure, molecular properties, and device efficiency. Our framework evaluates the chemical structure of the organic photovoltaic molecules directly and accurately. Since it does not involve density functional theory calculations, it makes fast predictions. The reliability of our framework is verified with data from previous reports and our newly synthesized organic molecules. Our work provides an efficient method for developing new organic optoelectronic materials. [ABSTRACT FROM AUTHOR]

Achieving the desired thermomechanical properties for highly solution‐processable organic semiconductors is challenging but crucial for heat tolerance of emerging optoelectronic devices. To this end, the successful synthesis of triphenylene–ethylenedioxythiophene‐dimethoxytriphenylamine (TP–ETPA), a star‐shaped organic semiconductor, is reported through a direct arylation reaction that involves ETPA, an electron donor, being grafted densely onto TP, which possesses six electron‐equivalent functionalization sites. Remarkably, TP–ETPA exhibits significantly improved hole mobility compared to 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) at a given hole density, owing to its lower energetic disorder, larger average centroid distance, and smaller reorganization energy. TP–ETPA, with a molecular weight of 2888 Da and lacking flexible chains, demonstrates extraordinary solubility in nonpolar solvents, enabling the formation of dense, pinhole‐free films through solution codeposition with an air‐doping promoter. By utilizing the p‐doped TP–ETPA composite as the hole transport layer, perovskite solar cells with an average power conversion efficiency of 23.4% are successfully fabricated. Notably, these devices display significantly enhanced operational stability and thermal stability at 85 °C. Molecular dynamics simulations reveal that the TP–ETPA‐based hole transport layer possesses a high cohesive energy density, resulting in a large elastic modulus and slow diffusion of external species. [ABSTRACT FROM AUTHOR]

Although the advances in organic solar cells (OSCs) have been considerable, their efficiency is still limited by recombination losses. Photogenerated electrons and holes are generally bound as localized excitons in organic semiconductors. The transition from excitons into free charges requires diffusion and dissociation processes, in which parasitic recombination losses exist. Reducing these losses is necessary for highly efficient OSCs. The crystallization behavior of the active layers can influence the efficiency of exciton diffusion and dissociation. In this work, different additives are delicately designed to control the crystallization behavior. It is found that the crystallization quality of active layers can be improved by controlling the aggregation of nonfullerene acceptors. The π–π stacking of blend films becomes compact, meanwhile, the crystallization in the vertical direction is more uniform. These are beneficial to the diffusion and dissociation of excitons. As a consequence, recombination losses are reduced and power convention efficiencies (PCEs) are improved significantly. Meanwhile, the general applicability of the additive is demonstrated in various organic photovoltaic systems, in which a PCE of 19.3% is achieved in D18:BTP‐eC9‐4F OSCs. This work provides a facile strategy to reduce the recombination losses of excitons for efficient devices. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive quantitative analysis of the photodiode (PD) is conducted and photovoltaic (PV) characteristics of organic non‐fullerene PCE10:ITIC‐4F devices before and after exposure to a 150 ns pulse of 170 keV proton irradiation with the fluence of 2·1012 p cm−2 that is equivalent to ≈6 years of operation at a low Earth orbit. While an expected initial performance reduction happened in the photodiode and photovoltaic operation modes, a hitherto unknown self‐healing effect in the organic devices is observed several days after the proton irradiation. The organic bulk‐heterojunction (BHJ) material properties and the multi‐mechanisms recombination processes before and after irradiation and during self‐healing are investigated. This analysis provides a quantitative understanding of the changes occurring in the device physics and points toward the relevant aspects of the self‐healing mechanism related to the dynamics of proton‐induced traps in the bulk of the organic active layer. Ultimately, the synergy of record lightweight features and newly discovered self‐healing of proton‐induced damage in organic PDs and solar cells highlights their great potential for applications in rapidly emerging space technology. [ABSTRACT FROM AUTHOR]

Many optoelectronic applications require organic semiconductor (OSC) materials with high electron affinity. In this work, a series of novel acceptor–donor–acceptor (A–D–A) materials with low-lying LUMO energy levels were designed and characterized. In this strategy, two acceptor dyes, bis-isatin and di-2-(2-oxindolin-3-ylidene) malononitrile, were connected by various π–bridges (benzene ring, benzo[c][1,2,5]thiadiazole, monothiophene, trithiophene). We varied the length of the π–conjugation of the central core and the linkage position of the acceptor core (4- vs. 6-position of the phenyl ring) to investigate the effect on the optical and electrochemical properties of the materials. We performed density functional theory (DFT) and time-dependent DFT (TD–DFT) studies to gain insight into the dyes' electronic properties by determining the energy levels. Our findings demonstrate that with increasing acceptor strength and π–conjugation length of the core, the wavelength of the longest absorption maximum as well as their respective extinction coefficients are enhanced, which results in band-gap reduction either by lowering the LUMO and/or raising the HOMO energy level of the molecules. The potential practical utility of these materials as electron-transport materials for perovskite solar cells (PSCs) has been demonstrated. [ABSTRACT FROM AUTHOR]

The combination of III–V compound semiconductor materials and organic semiconductor materials to construct hybrid solar cells is a potential pathway to resolve the problems of conventional doped p–n junction solar cells, such as complexities in fabrication process and high costs. This review presents the recent progress of organic–inorganic hybrid solar cells based on polymers and III–V semiconductors, from materials to devices. The available growth process for planar/nanostructured III–V semiconductor materials, along with patterning and etching processes for nanostructured materials, are reviewed. As an emphasis of this review, advanced device structure designs are reviewed for facilitation of carrier collection and high efficiency, at planar structure level and nanowire structure level, respectively. Optimization pathways for efficiency enhancement are discussed with respect to polymer layers and surface/interface passivation, respectively. Finally, perspectives on the future development of such hybrid cells are presented. [ABSTRACT FROM AUTHOR]

With power conversion efficiencies approaching 20%, organic solar cells can no longer be considered the ugly duckling of photovoltaics. Successes notwithstanding, there is still a need for further improvement of organic solar cells, both regarding energy and current management in these devices. At present, there are different and mutually exclusive interpretation schemes for the associated losses of energy and charge, hampering the rational design of next generations of organic solar cells. One critical factor that affects voltage, current, and fill factor losses is whether or not photogenerated charges are effectively near or far away from thermodynamic equilibrium. While it is commonly agreed that both the vibronic and (disordered) energetic structure of organic semiconductors affect the solar cell characteristics, the degree to which deviations from near‐equilibrium population of the associated energy level distributions matter for the photovoltaic performance is unclear: near‐equilibrium as well as kinetic descriptions have provided seemingly convincing descriptions of a wide range of experiments. Here, the most important concepts in relation to experimental results are reviewed, open questions are addressed and implications for device performance and improvement are highlighted. [ABSTRACT FROM AUTHOR]

Hybrid van der Waals heterostructures of organic semiconductors and transition metal dichalcogenides (TMDs) are promising candidates for various optoelectronic devices, such as solar cells and biosensors. Energy-transfer processes in these materials are crucial for the efficiency of such devices, yet they are poorly understood. In this work, we develop a fully microscopic theory describing the effect of the Förster interaction on exciton dynamics and optics in a WSe2/tetracene heterostack. We demonstrate that the differential absorption and time-resolved photoluminescence can be used to track the real-time evolution of excitons. We predict a strongly unidirectional energy transfer from the organic to the TMD layer. Furthermore, we explore the role temperature has in activating the Förster transfer and find a good agreement to previous experiments. Our results provide a blueprint to tune the light-harvesting efficiency through temperature, molecular orientation and interlayer separation in TMD/organic heterostructures. [ABSTRACT FROM AUTHOR]