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Among the emerging photovoltaic technologies, rigid perovskite solar cells (PSCs) have made tremendous development owing to their exceptional power conversion efficiency (PCE) of up to 25.7%. However, the record PCE of flexible PSCs (∼22.4%) still lags far behind their rigid counterparts and their mechanical stabilities are also not satisfactory. Herein, we report a highly efficient and stable flexible inverted PSC through modifying the interface between perovskite and hole transport layer (HTL) via Pentylammonium Acetate (PenAAc) molecule. Through synthetic manipulation of anion and cation, we show that the PenA

A major challenge hindering the further development of all-polymer solar cells (all-PSCs) employing polymerized small-molecule acceptors is the relatively low fill factor (FF) due to the difficulty in controlling the active-layer morphology. The issues typically arise from oversized phase separation resulting from the thermodynamically unfavorable mixing between two macromolecular species, and disordered molecular orientation/packing of highly anisotropic polymer chains. Herein, a facile top-down controlling strategy to engineer the morphology of all-polymer blends is developed by leveraging the layer-by-layer (LBL) deposition. Optimal intermixing of polymer components can be achieved in the two-step process by tuning the bottom-layer polymer swelling during top-layer deposition. Consequently, both the molecular orientation/packing of the bottom layer and the molecular ordering of the top layer can be optimized with a suitable top-layer processing solvent. A favorable morphology with gradient vertical composition distribution for efficient charge transport and extraction is therefore realized, affording a high all-PSC efficiency of 17.0% with a FF of 76.1%. The derived devices also possess excellent long-term thermal stability and can retain90% of their initial efficiencies after being annealed at 65 °C for 1300 h. These results validate the distinct advantages of employing an LBL processing protocol to fabricate high-performance all-PSCs.

A record power conversion efficiency (PCE) of over 19% is realized in planar-mixed heterojunction (PMHJ) organic solar cells (OSCs) by adopting the asymmetric selenium substitution strategy in making a pseudosymmetric electron acceptor, BS3TSe-4F. The combined molecular asymmetry with more polarizable selenium substitution increases the dielectric constant of the D18/BS3TSe-4F blend, helping lower the exciton binding energy. On the other hand, dimer packing in BS3TSe-4F is facilitated to enable free charge generation, helping more efficient exciton dissociation and lowering the radiative recombination loss (ΔE

Lead halide perovskite and organic solar cells (PSCs and OSCs) are considered as the prime candidates currently for clean energy applications due to their solution and low-temperature processibility. Nevertheless, the substantial photon loss in near-infrared (NIR) region and relatively large photovoltage deficit need to be improved to enable their uses in high-performance solar cells. To mitigate these disadvantages, low-bandgap organic bulk-heterojunction (BHJ) layer into inverted PSCs to construct facile hybrid solar cells (HSCs) is integrated. By optimizing the BHJ components, an excellent power conversion efficiency (PCE) of 23.80%, with a decent open-circuit voltage (Voc ) of 1.146 V and extended photoresponse over 950 nm for rigid HSCs is achieved. The resultant devices also exhibit superior long-term (over 1000 h) ambient- and photostability compared to those from single-component PSCs and OSCs. More importantly, a champion PCE of 21.73% and excellent mechanical durability can also be achieved in flexible HSCs, which is the highest efficiency reported for flexible solar cells to date. Taking advantage of these impressive device performances, flexible HSCs into a power source for wearable sensors to demonstrate real-time temperature monitoring are successfully integrated.

A low-bandgap (1.33 eV) Sn-based MA0.5 FA0.5 Pb0.75 Sn0.25 I3 perovskite is developed via combined compositional, process, and interfacial engineering. It can deliver a high power conversion efficiency (PCE) of 14.19%. Finally, a four-terminal all-perovskite tandem solar cell is demonstrated by combining this low-bandgap cell with a semitransparent MAPbI3 cell to achieve a high efficiency of 19.08%.

By creating an effective π-orbital hybridization between the fullerene cage and the aromatic anchor (addend), the azafulleroid interfacial modifiers exhibit enhanced electronic coupling to the underneath metal oxides. High power conversion efficiency of 10.3% can be achieved in organic solar cells using open-cage phenyl C61 butyric acid methyl ester (PCBM)-modified zinc oxide layer.

A new class of rationally designed mechanophores is developed for highly sensitive built-in strain sensors in polymer composites. These mechanophores are designed to regenerate the π-conjugation pathway between the electron donor and electron acceptor by force-induced cleavage of the covalent bond to form a fluorescent dipolar dye.

Low-temperature, solution-processable Cu-doped NiOX (Cu:NiOx ), prepared via combustion chemistry, is demonstrated as an excellent hole-transporting layer (HTL) for thin-film perovskite solar cells (PVSCs). Its good crystallinity, conductivity, and hole-extraction properties enable the derived PVSC to have a high power conversion efficiency (PCE) of 17.74%. Its general applicability for various elecrode materials is also revealed.

With developments in materials, thin-film processing, fine-tuning of morphology, and optimization of device fabrication, the performance of organic solar cells (OSCs) has improved markedly in recent years. Designing low-bandgap materials has been a focus in order to maximize solar energy conversion. However, there are only a few successful low-bandgap donor materials developed with near-infrared (NIR) absorption that are well matched to the existing efficient acceptors. Porphyrin has shown great potential as a useful building block for constructing low-bandgap donor materials due to its large conjugated plane and strong absorption. Porphyrin-based donor materials have been shown to contribute to many record-high device efficiencies in small molecule, tandem, ternary, flexible, and OSC/perovskite hybrid solar cells. Specifically, non-fullerene small-molecule solar cells have recently shown a high power conversion efficiency of 12% using low-bandgap porphyrin. All these have validated the great potential of porphyrin derivatives as effective donor materials and made DPPEZnP-TRs a family of best low-bandgap donor materials in the OSC field so far. Here, recent progress in the rational design, morphology, dynamics, and multi-functional applications starting from 2015 will be highlighted to deepen understanding of the structure-property relationship. Finally, some future directions of porphyrin-based OSCs are presented.

Generally, high light-harvesting efficiency, electron-injection efficiency, and charge-collection efficiency are the prerequisites for high-efficiency quantum-dot-sensitized solar cells (QDSCs). However, it is fairly difficult for a single QD sensitizer to meet these three requirements simultaneously. It is demonstrated that these parameters can be felicitously balanced by a cosensitization strategy through the adoption of environmental-friendly Zn-Cu-In-Se and Zn-Cu-In-S dual QD sensitizers with cascade energy structure. Experimental results indicate that: i) the combination of the dual QDs can improve the light-harvesting capability of the cells, especially in the visible light window; ii) the cosensitization approach can facilitate electron injection, benefitting from the cascade energy structure of the two QD sensitizers employed; iii) the charge-collection efficiency can be remarkably enhanced by the suppressed charge-recombination process due to the improved QD coverage on TiO2 . Consequently, this cosensitization strategy delivers a new certified efficiency record of 12.98% for liquid-junction QDSCs under AM 1.5G 1 sun irradiation. Moreover, the constructed cells exhibit good stability in a high-humidity environment.

In this work, a highly efficient parallel connected tandem solar cell utilizing a nonfullerene acceptor is demonstrated. Guided by optical simulation, each of the active layer thicknesses of subcells are tuned to maximize its light trapping without spending intense effort to match photocurrent. Interestingly, a strong optical microcavity with dual oscillation centers is formed in a back subcell, which further enhances light absorption. The parallel tandem device shows an improved photon-to-electron response over the range between 450 and 800 nm, and a high short-circuit current density (J SC ) of 17.92 mA cm-2 . In addition, the subcells show high fill factors due to reduced recombination loss under diluted light intensity. These merits enable an overall power conversion efficiency (PCE) of >10% for this tandem cell, which represents a ≈15% enhancement compared to the optimal single-junction device. Further application of the designed parallel tandem configuration to more efficient single-junction cells enable a PCE of >11%, which is the highest efficiency among all parallel connected organic solar cells (OSCs). This work stresses the importance of employing a parallel tandem configuration for achieving efficient light harvesting in nonfullerene-based OSCs. It provides a useful strategy for exploring the ultimate performance of organic solar cells.

A high-performance parallel tandem solar cell employing ultra-thin Ag as the intermediate anode is demonstrated, which comprises a semitransparent front sub-cell and a microcavity assisted back sub-cell. In addition to the extended optical field as a result of the tandem architecture, the prominent microcavity resonance formed in the back sub-cell enables such a parallel tandem configuration to possess high light utilization efficiency (the peak EQE value is over 80%) and a high photovoltaic performance of 9.2%. This study establishes an effective architecture that can be generally applicable to all organic materials for improving their performance.

A simple, low temperature solution process for Pb/Sn binary-metal perovskite planar-heterojunction solar cells is demonstrated. Sn inclusion substantially influences the band-gap, crystallization kinetics, and thin-film formation leading to a broadened light absorption and enhanced film coverage on ITO/PEDOT:PSS. As a result, the optimized device shows a PCE exceeding 10%, which is the best result for binary-metal perovskite solar cells so far.

and good fi lm quality in order to get optimal transparency and low sheet resistance. The continuity of ultrathin Ag fi lm is governed by its nuclea-tion and growth kinetics on substrate, which can be affected by the surface energy of the seed layer and the deposition condi-tions. The poor wettability of Ag on electrically insulating sub-strates (i.e., glass, polyethylene naphthalate (PEN)) often leads to poor fi lm continuity due to unfavorable disparity in surface energy and poor adhesion to the substrate.

Organic solar cells often show inefficient light harvesting due to a short absorption path length limited by the low charge mobility of organic semiconductors. We demonstrate a flexible organic solar cell in a microcavity configuration using a TeO2/Ag semitransparent electrode to confine the optical field within the device with significant performance improvements and reaching a power conversion efficiency of 8.56%.

Solar photon-to-electron conversion with polymer solar cells (PSCs) has experienced rapid development in the recent few years. Even so, the exploration of molecules and devices in efficiently converting near-infrared (NIR) photons into electrons remains critical, yet challenging. Herein presented is a family of near-infrared nonfullerene acceptors (NIR NFAs, T1-T4) with fluorinated regioisomeric A-Aπ-D-Aπ-A backbones for constructing efficient single-junction and tandem PSCs with photon response up to 1000 nm. It is found that the tuning of the regioisomeric bridge (Aπ) and fluoro (F)-substituents on a molecular skeleton strongly influences the backbone conformation and conjugation, leading to the optimized optoelectronic and stable stacking of resultant NFAs, which eventually impacts the performance of derived PSCs. In PSCs, the proximal NFAs with varied F-atoms (T1-T3) mostly outperform than that of distal NFA (T4). Notably, single-junction PSC with PTB7-Th:T2 blend can reach 10.87% power conversion efficiency (PCE), after implementing a solvent additive to improve blend morphology. Moreover, efficient tandem PSCs are fabricated through integrating such NIR cells with mediate bandgap nonfullerene-based subcells, to achieve a PCE of 14.64%. The results reveal the structural design of organic semiconductor and device with improved photovoltaic performance.

A novel ladder-type donor (IDTT) is developed by substituting the two outward thiophenes of the IDT donor with two thieno[3,2-b]thiophenes. The polymer derived from this donor possesses longer effective conjugation and better planarity, which improves electron delocalization along the polymer backbone and charge mobility. The polymer solar cell device using PIDTT-DFBT shows a high power conversion efficiency of 7.03% with a large open-circuit voltage of 0.95 V without using any additives or post-solvent/thermal annealing processes.

ITO-free polymer solar cells with efficiencies as high as 6.6% and 5.8% are fabricated on glass and polyethylene naphthalate (PEN) by using TeO(2) to enhance the in-coupling of light in an Ag-Ag microcavity. These cells exhibit higher performance, selective microcavity resonance as a function of the thickness of TeO(2) , and better bending stability than flexible devices made with ITO.

Conjugated polymers are a novel class of solution-processable semiconducting materials with intriguing optoelectronic properties. [ 1 ] They have received great attention as active components in organic electronic devices such as organic photovoltaic cells (OPVs), organic light-emitting diodes (OLEDs), and organic fi eld-effect transistors (OFETs) due to their light weight, facile tuning of electronic properties through molecular engineering, and ease of processing. The performance and lifetime of conjugated polymer-based electronic devices are critically dependent on the bulk properties of the active materials and the interfacial properties of electrode/polymer contacts. [ 2–4 ] In these devices, the electrode(s) either inject charge into or extract charges from the organic semiconductor layer(s). Mismatch of the work functions between metal or metal oxide electrodes and molecular orbital energy levels of organic semiconductors can lead to high contact resistance, which decreases the charge injection and extraction effi ciency. Therefore, it is essential to minimize contact resistance at the electrode/organic semiconductor interface. To improve charge injection/extraction across the electrode/ organic semiconductor interface, several strategies have been developed. One is to tune the interfacial dipole across the electrode/semiconductor interface to reduce the injection/collection energy barrier. This can be achieved by modifying the electrode surface with self-assembled dipolar molecules to tune the energy level alignment at the semiconductor/electrode interface. [ 5–7 ] Alternatively, the introduction of a thin layer of polymer surfactant that contains polar side chains between the conjugate polymer/electrode interface can also be used to improve the interfacial properties. The polar side chains can provide not

A variety of dopant-free hole-transporting materials (HTMs) is effectively applied in perovskite solar cells (PSCs); however, HTMs with the additional function of HTM/perovskite interfacial optimization that is crucial to their photovoltaic performance are really limited. In this work, the design of an HTM bearing an intensive exposure of its functional aromatic rings to perovskite layer via side-chain engineering is attempted. With an edge-on orientation and a short distance to perovskite, this HTM was expected to display an excellent ability to extract holes from and passivate defects in the perovskite layer. To demonstrate this strategy, an alternating copolymer was constructed with a 2,5-di-2-ethylhexyloxy-1,4-phenylene unit and a bithiophene unit, and the PSC based on this polymer showed an ultrahigh short-circuit current density of 25.50 mA cm-2 , which was the highest so far presented by dopant-free organic HTMs. A comparable power conversion efficiency of 19.68% (certified: 19.5%) to that of a control 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) device (19.81%) was thus obtained, which is the highest value ever reported for mesoporous PSCs based on dopant-free polymeric HTMs.

Employing a layer of bulk-heterojunction (BHJ) organic semiconductors on top of perovskite to further extend its photoresponse is considered as a simple and promising way to enhance the efficiency of perovskite-based solar cells, instead of using tandem devices or near infrared (NIR)-absorbing Sn-containing perovskites. However, the progress made from this approach is quite limited because very few such hybrid solar cells can simultaneously show high short-circuit current (JSC) and fill factor (FF). To find an appropriate NIR-absorbing BHJ is essential for highly efficient, organic, photovoltaics (OPV)/perovskite hybrid solar cells. The materials involved in the BHJ layer not only need to have broad photoresponse to increase JSC, but also possess suitable energy levels and high mobility to afford high VOC and FF. In this work, a new porphyrin is synthesized and blended with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) to function as an efficient BHJ for OPV/perovskite hybrid solar cells. The extended photoresponse, well-matched energy levels, and high hole mobility from optimized BHJ morphology afford a very high power conversion efficiency (PCE) (19.02%) with high Voc, JSC, and FF achieved simultaneously. This is the highest value reported so far for such hybrid devices, which demonstrates the feasibility of further improving the efficiency of perovskite devices.

Organic white-light-emitting diodes (OWLEDs) have attracted considerable attention due to their potential applications in fullcolor flat panel displays, back-lighting sources for liquid-crystal displays, and solid-state lighting. [1‐3] To achieve high-efficiency OWLEDs, efficient and balanced electron and hole injection and transport from cathode and anode are essential. This results in commonly used multilayer device structures, including the transparent conducting indium tin oxide (ITO) anode, holetransport/injection layer (HTL), emissive layer (EML), electrontransport/injection layer (ETL), and metal cathode. For small molecule OWLEDs, this kind of multilayer structure can be easily produced by vacuum deposition with very thin emissive and transport layers to maximize light output and minimize power consumption of the devices. As a result, vacuum deposited OWLEDs have exhibited higher efficiencies than standard incandescent light sources (13‐20 lm W � 1 ). [2‐7] Polymer OWLEDs combining the advantages of simpler fabrication and lower production cost, especially for the large-area devices, are particularly attractive, because they can be fabricated by simple techniqueslikespin-coatingorink-jetprinting. [8‐20] However,itis very difficult to realize well-controlled multilayer device structures for polymer OWLEDs. Therefore, polymer OWLEDs often exhibit poorer performance than those obtained from small molecule OWLEDs. Only very few polymer OWLEDs reported so far have efficiencies comparable to that of the incandescent light bulbs. [14,19] Yang et al. have recently reported high-performance polymer OWLEDs with a power efficiency (PE) of 16 lm W � 1 using Cs2CO3 as the electron-injection/hole blocking layer in the devices. [14] By using an alcohol-soluble conjugated polymer as ETL,we havealso shown high-efficiency polymer phosphorescent OWLEDs with a PE of 14.5 lm W � 1 . [19]

valuesoriginatefromthelossofchargecarriersthroughleakagepathsincluding pinholes in the films and the recombination andtrapping of the carriers during their transit through the cell,leading to a decrease in device performance.Modification of electrodes has been commonly employed toimprove the contact between the active organic layer andelectrodes. At the indium tin oxide (ITO) anode side, a thinbuffer layer of a conductive polymer, poly(3,4-ethylene-dioxylene thiophene):poly(styrene sulfonic acid) (PED-OT:PSS), is often used to increase the work-function of ITOfor effective hole collection.

Organic and polymer light-emitting diodes (LEDs) have been the subject of intensive investigation in recent years because of their potential as emissive elements for flat-panel displays and white-light sources for general lighting. As dualinjection devices, multilayer structures with discrete hole-injection layers (HILs) and/or hole-transport layers (HTLs), light-emitting layers (EMLs), and electron-transport layers (ETLs) are necessary for high efficiency, where these layers can be optimized, respectively, according to their functions. [1–3] For LEDs based on small molecules, it is rather straightforward to adopt this multilayer strategy via layer-bylayer vacuum deposition. However, for polymer-based LEDs, where solution-based casting or spin-coating is the basic way to form films, it is very challenging to form multilayer structures, because of solvent erosion of previously deposited layers during spin-coating. [4] To overcome this problem, a

Poled electro-optic (EO) polymers have enabled many advances in the exploration of high-speed and broadband information technologies. Polymer based EO devices have been demonstrated to have large bandwidths (over 110 GHz), low driving voltages, and sustain their performance in a flexible form or under extreme environmental conditions. For optical circuits, EO polymers can be easily integrated with striplineor ring-structured waveguides made of sol–gels, low-loss fluorinated polymers, silicon slots, conducting oxides, and photonic crystals. Recently, EO polymers have also been utilized for the generation/detection of a gap-free pulsed THz system with a bandwidth up to ca. 12 THz. Large numbers of discrete photonic components need to be inserted into integrated systems of telecommunication and silicon microphotonics, especially where an extreme amount of data is required to travel in a very small space. Therein lies the great challenge for polymer-based EO technologies: to have thermally stable EO coefficients (r33) of around 500 pm V at wavelengths of 1.31 or 1.55 lm. Currently, the most commonly used materials for polymeric EO devices are based on poled polymers with r33 values around 50–80 pm V at wavelengths of 1.31 or 1.55 lm. In these materials, dipolar nonlinear optical (NLO) chromophores have been doped or incorporated at a level of ca. 20– 25 wt % to reach their maximum r33 values. [5–10] Beyond such a moderate loading of chromophores, strong intermolecular electrostatic interactions severely limit the poling-induced polar order and cause phase-separation problems between chromophores and polymers. To further improve EO activity, research efforts have focused on developing shape-engineered chromophores with high molecular optical nonlinearities (lb), where lb is a product of first hyperpolarizability and the dipole moment of the NLO chromophore, and increasing order within the matrices by controlling the nanoscale architecture of macromolecules. In our recent study we have demonstrated, using Diels–Alder (DA) “click chemistry” to post-functionalize NLO chromophores onto polymers, that high chromophore loading levels (up to 35 wt %) and large r33 values (up to 110 pm V) could be achieved in in situ generated side-chain dendronized NLO polymers with non-reacted chromophores as guest dopants. This opens a new avenue to explore optimal host–guest combinations and to develop an efficient way to control lattice hardening in these hybrid polymers. The ultimate goal is to simultaneously achieve very large EO activity, good thermal stability, high optical transparency, and excellent mechanical properties within the same material via molecular design and facile processing. In this paper, we report a novel method to disperse a highly efficient secondary chromophore into in situ crosslinked NLO polymer networks, leading to both enhanced EO activity (> 260 pm V at 1.31 lm) and alignment stability at 85 °C. In photorefractive (PR) polymers and liquid-crystal (LC) systems, binary chromophore mixtures have been shown to elevate the loading density of small dipolar dyes without causing phase separation. We have extended this further by incorporating highly polarizable NLO chromophores into these binary systems. In addition, DA click chemistry has also been employed to improve the physical properties of these materials. This combined effort demonstrates that binary mixtures of large-bl chromophores can be loaded into side-chain NLO matrices and efficiently poled to give EO activities higher than the summed value of two added chromophores. These systems can also be mildly cured to ensure a thermally stable EO response. The EO polymers studied in this work exist as a three-component host–guest system (Fig. 1). The host polymer is a copolymer, poly[(methyl methacrylate)-co-(9-anthracenyl methyl methacrylate)] (PMMA-AMA), with around 10 mol % of the anthracenyl moiety. To this host, AJC146 was added together with compound 1a, 1b, or 1c as binary guest chromoC O M M U N IC A TI O N S

Polymer optical waveguide devices will play a key role in several rapidly developing areas of broadband communications, such as optical networking, metropolitan/access communications, and computing systems due to their easier processibility and integration over inorganic counterparts. The combined advantages also makes them an ideal integration platform where foreign material systems such as YIG (yttrium iron garnet) and lithium niobate, and semiconductor devices such as lasers, detectors, amplifiers, and logic circuits can be inserted into an etched groove in a planar lightwave circuit to enable full amplifier modules or optical add/drop multiplexers on a single substrate. Moreover, the combination of flexibility and toughness in optical polymers makes it suitable for vertical integration to realize 3D and even all-polymer integrated optics. In this review, a survey of suitable optical polymer systems, their processing techniques, and the integrated optical waveguide components and circuits derived from these materials is summarized. The first part is focused on discussing the characteristics of several important classes of optical polymers, such as their refractive index, optical loss, processibility/mechanical properties, and environmental performance. Then, the emphasis is placed on the discussion of several novel passive and active (electro-optic and thermo-optic) polymer systems and versatile processing techniques commonly used for fabricating component devices, such as photoresist-based patterning, direct lithographic patterning, and soft lithography. At the end, a series of compelling polymer optical waveguide devices including optical interconnects, directional couplers, array waveguide grating (AWG) multi/demultiplexers, switches, tunable filters, variable optical attenuators (VOAs), and amplifiers are reviewed. Several integrated planar lightwave circuits, such as tunable optical add/drop multiplexers (OADMs), photonic crystal superprism waveguides, digital optical switches (DOSs) integrated with VOAs, traveling-wave heterojunction phototransistors, and three-dimensionally (3D) integrated optical devices are also highlighted.

Despite the breakthrough of over 22% power conversion efficiency demonstrated in organic-inorganic hybrid perovskite solar cells (PVSCs), critical concerns pertaining to the instability and toxicity still remain that may potentially hinder their commercialization. In this study, a new chemical approach using environmentally friendly strontium chloride (SrCl2 ) as a precursor for perovskite preparation is demonstrated to result in enhanced device performance and stability of the derived hole-conductor-free printable mesoscopic PVSCs. The CH3 NH3 PbI3 perovskite is chemically modified by introducing SrCl2 in the precursor solution. The results from structural, elemental, and morphological analyses show that the incorporation of SrCl2 affords the formation of CH3 NH3 PbI3 (SrCl2 )x perovskites endowed with lower defect concentration and better pore filling in the derived mesoscopic PVSCs. The optimized compositional CH3 NH3 PbI3 (SrCl2 )0.1 perovskite can substantially enhance the photovoltaic performance of the derived hole-conductor-free device to 15.9%, outperforming the value (13.0%) of the pristine CH3 NH3 PbI3 device. More importantly, the stability of the device in ambient air under illumination is also improved.

Novel nonlinear optical (NLO) building blocks can be placed into the periphery, branch, or core of a dendrimer to construct precise molecular architecture with predetermined chemical composition. The site-isolation effect, through the encapsulation of active moieties by dendrons, or the cooperative effect, through the coherent interaction among the same or different kinds of active blocks in the dendrimer, can greatly enhance the performance of NLO materials. This paper provides a review of recent developments in dendrimers for NLO applications, such as electro-optics (E-O), photorefractive (PR) materials, second harmonic generation (SHG), and two-photon absorption (TPA).

The p-type inorganic semiconductor CuGaO2 as a hole-transporting layer (HTL) in perovskite solar cells (PSCs) provides higher carrier mobility, better-energy level matching, and superior stability, as well as low-temperature processing technique. Compared to organic HTL, a very competitive PCE of 18.51% with long-term stability is achieved. This indicates that CuGaO2 is a promising HTL for efficient and stable PSCs.