Efficient Hole Transport Research Articles

The Effect of Different Precursor Solutions on the Structural, Morphological, and Optical Properties of Nickel Oxide as an Efficient Hole Transport Layer for Perovskite Solar Cells

Perovskite solar cell (PSC) technologies have recently become a popular research topic. The hole transport layers (HTL) are important in establishing stable and efficient PSC by regulating charge absorption, interlayer recombination losses, and band alignment. Spiro-OMeTAD was extensively used as the HTL to fabricate highly efficient PSCs. Despite Spiro-OMeTAD having the benefit of providing high PCEs, it is costly, hazardous to the ecology, and cannot provide high efficiencies in the lack of additional additives that can reduce their stabilities. Inorganic HTL, specifically nickel oxide (NiO), has garnered much interest due to its low-cost, enhanced mobility, and strong stability to attain high efficiency. This study investigated different precursor solutions of NiO synthesis (Method I, II, and III) and deposited using the spin coating approach. The films were annealed at different annealing temperatures (400°C, 550°C, and 700°C) and evaluated by X-ray powder diffraction (XRD), UV-Vis spectroscopy, and Scanning electron microscopy (SEM) to test their structural, morphological, and optical characteristics, respectively. The findings of XRD revealed that a higher annealing temperature increases the crystallite size and decreases the microstrain through the study from Scherrer’s and Williamson-Hall’s (WH) equations. From the SEM analysis, the films show uniformity, large crystals, and agglomeration of particles. The annealing temperature from 400°C to 700°C reduced bandgap energy from 3.6 eV to 2.1 eV. According to the result, NiO produced at an annealing temperature of 700°C (Method I) exhibited the best characteristics and might be a viable option for HTL in PSCs.

Versatile Self‐Assembled Hole Transport Monolayer Enables Facile Processing Organic Solar Cells over 18% Efficiency with Good Generality

AbstractSimplifying solution‐processing of bulk‐heterojunction (BHJ) organic solar cells (OSCs) via efficient interfacial layers with good generality is in great demand for pushing their large‐scale applications. In this study, such a novel and cost‐effective self‐assembled monolayer (SAM) is reported herein as efficient hole transport layer (HTL) for high efficiency OSCs. The SAM‐structured 4‐(5,9‐dibromo‐7H‐dibenzo[c,g]carbazol‐7‐yl)butyl)phosphonic acid (DCB‐BPA) enables not only enhanced photon harvesting in the active layer but also minimized nonradiative recombination losses to improve interface charge extraction/transport. As a consequence, high short‐circuit current (≈28.07 mA cm−2) is achieved for PM6:BTP‐eC9 based OSCs to deliver a champion power conversion efficiency of 18.16%, among the highest values for OSCs using small organic HTLs to date. Importantly, good generality of this SAMs is demonstrated for representative high‐efficiency BHJ OSCs systems like PM6:Y6 and PM6:PC61BM, outperforming conventional poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate)‐based counterparts. Excitingly, the SAM is applicable for large‐area HTL processing via immersion method, affording 16.59% efficiency for PM6:BTP‐BO‐4Cl based OSCs. This study highlights the great potential of engineered SAMs for facile large‐scale fabrication of high performance OSCs.

Copper‐Doped InxGa2−xO3 Nanocrystals as Efficient Hole Transport Materials of Perovskite Solar Cells by Regulating Energy Levels

The hole transport layers are critical for collecting holes and suppressing recombination in perovskite solar cells, and metal oxides are superior due to their green synthesis and good ambient stability. Although gallium oxide is rarely applied as the hole transport layers of devices for the mismatch of valence bands with perovskite materials, copper dopants can provide an additional transport channel via their impurity levels. Herein, InxGa2−xO3 nanocrystals with copper dopants are synthesized as the hole transport material of perovskite solar cells by the hydrothermal method, and uniform hole transport layers can be deposited by spin‐coating at a low temperature of 100 °C. The energy position of impurity levels and the hole transport ability of hole transport layers can be regulated by incorporating indium ions. In the optimized condition, the efficiencies of devices increase from 19.6% to 21.4%, which is related to the improvement of the charge extraction process and carrier recombination process. And the photostability of devices can be improved simultaneously. This work provides an efficient hole transport material for inverted perovskite solar cells and demonstrates the regulation of transport channels via impurity levels.

GeAs as an emerging p-type van der Waals semiconductor and its application in p–n photodiodes

van der Waals (vdW) layered materials have shown great potential for future optoelectronic applications owing to their unique and variable properties. In particular, two-dimensional layered materials enable the creation of various circuital building blocks via vertical stacking, e.g. the vertical p–n junction as a key one. While numerous stable n-type layered materials have been discovered, p-type materials remain relatively scarce. Here, we report on the study of multilayer germanium arsenide (GeAs), another emerging p-type vdW layered material. We first verify the efficient hole transport in a multilayer GeAs field-effect transistor with Pt electrodes, which establish low contact potential barriers. Subsequently, we demonstrate a p–n photodiode featuring a vertical heterojunction of a multilayer GeAs and n-type MoS2 monolayer, exhibiting a photovoltaic response. This study promotes that 2D GeAs is a promising candidate for p-type material in vdW optoelectronic devices.

Properties of Electro-Deposited CuSCN Thin Films with Different Electrodeposition Charge Density

The development of efficient CuSCN hole transport layers is crucially important for achieving high photovoltaic performance in inorganic perovskite devices. In this study, the effects of electrodeposition charge density on the morphological/microstructural and electrical properties and the formation mechanism of electro-deposited CuSCN films are investigated and discussed. The results indicate that the charge density is the key factor that governs not only the thickness, but also morphological, electrical, and surface properties of the electro-deposited CuSCN films. For the energy band diagram property, we found that when the charge density is 120 mC cm−2 (named as CD120), the valance band of CuSCN near ITO work function. This excellent property can efficiently improve the photovoltaic performance of inorganic perovskite devices, where ITO and CuSCN are employed, owing to the reduction of energy barrier. Among the films electro-deposited at different charge densities, the CD120 exhibits the highest mobility, possibly due to the excess amount of SCN in the thin film.

Blade‐Coated Carbon Electrode Perovskite Solar Cells to Exceed 20% Efficiency Through Protective Buffer Layers

AbstractPerovskite solar cells with carbon electrode have a commercial impact because of their facile scalability, low‐cost, and stability. In these devices, it remains a challenge to design an efficient hole transport layer (HTL) for robust interfacing with perovskite on one side and carbon on another. Herein, an organic/inorganic double planar HTL is constructed based on polythiophene (P3HT) and nickel oxide (NiOx) nanoparticles to address the named challenge. Through adding an alkyl ammonium bromide (CTAB) modified NiOx nanoparticle layer on P3HT, the planar HTL achieves a cascade type‐II energy level alignment at the perovskite/HTL interfaces and a preferential ohmic contact at NiOx/carbon electrode, which greatly benefits in charge collection while suppressing charge transfer recombination. Besides, compared with the single P3HT layer, the planar composite enables a robust interfacial contact by protecting perovskite from being corroded by carbon paste during fabrication. As a result, the blade‐coated FA0.6MA0.4PbI3 perovskite solar cells (fabricated in ambient air in fume hood) with carbon electrode deliver an efficiency of 20.14%, the highest value for bladed coated carbon and perovskite solar cells, and withstand 275 h maximum power point tracking in air without encapsulation (95% efficiency retained).

Modulating buried interface with multi-fluorine containing organic molecule toward efficient NiOx-based inverted perovskite solar cell

Inverted perovskite solar cells (p-i-n PSCs) with nickel oxide (NiOx) as hole transport layer (HTL) have attracted tremendous attention due to the stable performance and ease of preparation. However, the NiOx/perovskite interface in the inverted perovskite solar cells (p-i-n PSCs) usually suffers from energy level mismatch, low conductivity, lattice mismatch, existence of surface defects etc., limiting the improvement of power conversion efficiency (PCE) and durability. Fluorine-containing materials have desired interface modification effect and are popular in the bulk and upper interface of perovskite, but rarely appear at NiOx/perovskite interface to address above issues. Herein, an interfacial modification strategy with a multi-fluorine organic molecule 6FPPY, is proposed to manage the buried interface of NiOx-based p-i-n PSC. Theoretical calculation and experimental results show that 6FPPY bridges the NiOx/perovskite interface through moieties with F atoms, producing a NiOx film with higher hole transport efficiency, releasing the residual strain of perovskite film, passivating the NiOx/perovskite interface defects, and suppressing the detrimental reaction between NiOx and perovskite. Consequently, p-i-n PSCs with 6FPPY-modified NiOx achieve a champion PCE of 24.0%, which is superior to the reference device. After 6FPPY modification, PSC can retain above 90% of the initial PCE after 200 h illumination at maximum power point in N2 atmosphere and exhibit better stability than the reference device during 1080 h storage under 60% humidity and 30–35 ℃.

Pure‐Iodide Wide‐Bandgap Perovskites for High‐Efficiency Solar Cells by Crystallization Control

AbstractWide‐bandgap perovskite is a vital part of perovskite‐based tandem solar cells. Currently, wide‐bandgap perovskites are typically based on mixed‐halide (I/Br) materials, but suffer from photoinduced phase separation. The pure‐iodide formamidine/cesium (FA/Cs) based FAxCs1−xPbI3 perovskites with high Cs content are good candidates, whereas the control of crystallization is challenging due to the complex crystallization kinetics. Here, pure‐iodide FA0.5Cs0.5PbI3 wide‐bandgap perovskite solar cells is reported. As an acidic diammonium salt, methylenediaminium dichloride (MDACl2) is applied as an additive to control the whole crystallization process of perovskite films, including both nucleation and crystal growth. Starting from the solution chemistry, the MDACl2 additive with acidity and strong solvation properties can effectively regulate the chemical composition of perovskite precursor, thus inhibiting the growth of undesired 1D intermediates during the nucleation process. Besides, the incorporation of larger‐sized MDA2+ into the lattice compensates for the tolerance factor and accelerates the ion exchange reaction between FA+ and Cs+ in the crystal growth process. As a result, the crystallinity of the perovskite films is significantly improved, benefitting from the dual function of MDACl2. Finally, the efficiency of hole transport layer‐free carbon electrode‐based wide‐bandgap perovskite solar cells reaches 18.52%, which is the highest reported so far.

First-principles prediction of two-dimensional Janus XMInZ[formula omitted](X [formula omitted] Cl, Br, I; M [formula omitted] Mg, Ca; and Z [formula omitted] S, Se, and Te) with promising spintronic and photocatalytic properties

Janus two-dimensional (2D) materials with asymmetric structures and intrinsic dipole moments have recently drawn enormous attention due to their appealing performance in diverse fields of nanoelectronics, optoelectronics, spintronics, and photocatalytic water splitting. In this paper, we propose a novel 2D Janus family named XMInZ2(X = Cl, Br, I; M = Mg, Ca; and Z = S, Se, and Te) and investigate their properties employing first-principles calculations. Using phonon dispersion, seventeen compounds of the predicted XMInZ2 monolayers are proved to be dynamically stable. The electronic band structures reveal that all stable XMInZ2 monolayers are direct bandgap semiconductors among which XMgInZ2 have larger bandgaps than XCaInZ2 monolayers. Lack of mirror symmetry gives rise to distinct Rashba spin-splitting (RSS) at Γ point of conduction bands in most XMInZ2 monolayers and the largest Rashba coefficient (αRΓC= 1.112 eVÅ) belongs to BrCaInTe2. Furthermore, comparing the projected band structures with and without the spin–orbit coupling (SOC) effect, it is found that the inclusion of SOC leads to band inversion between the lower conduction band (LCB) and upper valence band (UVB) of ICaInS2 monolayer. In terms of photocatalytic properties, some Janus XMInZ2 monolayers possess appropriate band edge positions for overall water splitting owing to their intrinsic dipole moments. Particularly, BrMgInTe2, BrCaInTe2, and ICaInTe2 due to their smaller bandgaps, larger solar light absorptions, and efficient separation and transport of electrons and holes are superior photocatalysts for water splitting. These explorations can pave the way for the design of highly efficient spintronic and photocatalytic devices.

State-of-the-Art Techniques on Asymmetrical Perylene Diimide Derivatives: Efficient Electron-Transport Materials for Perovskite Solar Cells

Electron-transport materials (ETMs) play an important role in the injection and transfer of electrons at the interface of perovskite solar cells (PSCs). In this work, four PDI (perylene diimide) derivatives (PDI-3, PDI-4, PDI-5, and PDI-6) were designed on the basis of two asymmetrical PDIs (PDI-1 and PDI-2), which were found to have potential application in organic solar cells. State-of-the art techniques were used to investigate the molecular geometry, crystal packing, and electronic properties of these PDIs. The quantum chemical calculations reveal that designed PDIs have more matching energy level with MAPbI3, which will promote the efficient electron extraction and block undesirable hole transport from perovskite to the ETM layer. The crystal structures of asymmetrical PDIs exhibit a quasi-two-dimensional (2D) π–π stacking motif ascribed to the strong interaction of oxygen atoms in alkoxy benzamide/benzoate groups and hydrogen atoms in the molecule. A largely improved electron mobility of PDI-3 to PDI-6 (0.24, 0.41, 0.40, and 0.15 cm2 V–1 s–1, respectively) was obtained compared to the values for PDI-1 and PDI-2 (6.53 × 10–10 and 1.35 × 10–10 cm2 V–1 s–1, respectively). The calculated electron mobility of the designed PDI-4 and PDI-5 (0.41 and 0.40 cm2 V–1 s–1, respectively) is higher than that of a symmetrical PDI derivative (PDI-0, 0.30 cm2 V–1 s–1). The interface property of PDI-4/MAPbI3 and PDI-5/MAPbI3 is better than that of PDI-0/MAPbI3 due to the reinforced O···Pb interaction between the oxygen atom in the branched chain of PDI-4/PDI-5 and Pb of the perovskite surface. The enhanced defect (methylammonium vacancy, lead vacancy, and iodine substituted at the lead site) passivation ability for perovskite was also found in PDI-4 and PDI-5, which will lead to a high-performance perovskite layer. The current investigation not only offers a few promising ETMs but also provides a useful strategy for introducing asymmetrical functional groups into PDIs to obtain more efficient ETMs of PSCs.

Design of new bithieno thiophene (BTTI) central core-based small molecules as efficient hole transport materials for perovskite solar cells and donor materials for organic solar cells

This present study focuses on designing five bithienothiophene (BTTI) central core-based small molecules (MPA-BTTI-A1-MPA-BTTI-A5) in exploring the optoelectronic properties to ensure their potentiality as donor candidates for organic solar cells (OSCs) and HTMs. MPA-BTTI-A1 and MPA-BTTI-A3 are tailored by the replacing thiophene-bridge end-capped acceptors on one side terminal of reference (MPA-BTTI-R). Similarly, MPA-BTTI-A2, MPA-BTTI-A4 and MPA-BTTI-A5 have been designed by employing the same strategy on both side terminals. To ascertain stable geometric structures, CAM-B3LYP/6-311G (d,p) is selected and used in all computational simulations. The MPA-BTTI-A1 exhibits the least energy gap of 1.69 eV with greatest λmax at 722 nm in dichloromethane (DCM) and highest dipole moment of 19.59 D in DCM solvent, indicating excellent miscibility as compared to the model/reference. All newly fabricated molecules (MPA-BTTI-A1- MPA-BTTI-A5) suggest excellent operational efficiency due to their higher Voc also relatively high-power conversion efficiency (PCE) in comparison to reference. Also, all fabricated molecules are attributed with a greater estimated PCE of range (20.74–40.3%), than reference (PCE = 16%). The highest electron mobility of 0.0871 eV is observed in MPA-BTTI-A3 andMPA-BTTI-A2 exhibits the highest hole mobility of 0.1334 eV. Hence, the modification scheme is a promising way in designing proficient photovoltaic materials, paving ways for new design and advancement of a small-molecule HTMs for donor contributors for organic solar cells (OSCs) and in PSCs.

A Multifluorination Strategy Toward Wide Bandgap Polymers for Highly Efficient Organic Solar Cells

AbstractCreating new electron‐deficient unit is highly demanded to develop high‐performance polymer donors for non‐fullerene organic solar cells (OSCs). Herein, we reported a multifluorinated unit 4,5,6,7‐tetrafluoronaphtho[2,1‐b : 3,4‐b′]dithio‐phene (FNT) and its polymers PFNT‐F and PFNT‐Cl. The advantages of multifluorination: (1) it enables the polymers to exhibit low‐lying HOMO (≈−5.5 eV) and wide band gap (≈2.0 eV); (2) the short interactions (F⋅⋅⋅H, F⋅⋅⋅F) endow the polymers with properties of high film crystallinity and efficient hole transport; (3) well miscibility with NFAs that leads to a more well‐defined nanofibrous morphology and face‐on orientation in the blend films. Therefore, the PFNT‐F/Cl : N3 based OSCs exhibit impressive FF values of 0.80, and remarkable PCEs of 17.53 % and 18.10 %, which make them ranked the best donor materials in OSCs. This work offers new insights into the rational design of high‐performance polymers by multifluorination strategy.

A Multifluorination Strategy Toward Wide Bandgap Polymers for Highly Efficient Organic Solar Cells.

Creating new electron-deficient unit is highly demanded to develop high-performance polymer donors for non-fullerene organic solar cells (OSCs). Herein, we reported a multifluorinated unit 4,5,6,7-tetrafluoronaphtho[2,1-b : 3,4-b']dithio-phene (FNT) and its polymers PFNT-F and PFNT-Cl. The advantages of multifluorination: (1) it enables the polymers to exhibit low-lying HOMO (≈-5.5 eV) and wide band gap (≈2.0 eV); (2) the short interactions (F⋅⋅⋅H, F⋅⋅⋅F) endow the polymers with properties of high film crystallinity and efficient hole transport; (3) well miscibility with NFAs that leads to a more well-defined nanofibrous morphology and face-on orientation in the blend films. Therefore, the PFNT-F/Cl : N3 based OSCs exhibit impressive FF values of 0.80, and remarkable PCEs of 17.53 % and 18.10 %, which make them ranked the best donor materials in OSCs. This work offers new insights into the rational design of high-performance polymers by multifluorination strategy.

Super aligned carbon nanotubes for interfacial modification of hole transport layer in polymer solar cells

This work presents a facile and innovative method for the insertion of super aligned carbon nanotubes (CNTs) as sheets over and within poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as an efficient hole transport layer (HTL) in the inverted type polymer solar cell. CNTs sheets drawn from the vertically grown CNTs arrays were extracted via a sharp-edge blade and were directly transferred to the surface of PEDOT:PSS followed by the deposition of thermally evaporated silver electrode. All the characteristic photovoltaic parameters of the device have been improved with the insertion of special patterened CNTs sheets as compared to the standards device (without CNTs sheets). Power conversion efficiency (PCE) improved from 2.14% to 3.69% with the increased short circuit current density from 9.12 mAcm−2 to 11.58 mAcm−2 and fill factor from 0.48 to 0.58, respectively. Scanning electron microscopy (SEM) images revealed the successful insertion of CNTs without any destructive impact on the integrity of CNTs structure. Moreover, the performance and stability of the device have also been optimized by increasing the thickness of CNTs sheets. Electrochemical impedance spectroscopy (EIS) showed the reduction in charge transfer resistance on replacement of CNTs sheets-modified PEDOT:PSS as HTL as compared to simple PEDOT:PSS, which may be attributed to the creation of ordered steps which provided cascade routes for the better charge (holes) collection. Facile modification of the anode materials with improved device performance for designing of new device architecture will help scale-up production of low-cost, stable, and efficient polymer solar cells.

Rationally heteroarylated pyridines as hole transport materials for OLEDs.

The advancement in developing highly efficient hole transport materials for OLED devices has been a challenge over the past several years. For an efficient OLED device, there should be an efficient promotion of charge carriers from each electrode and effective confinement of triplet excitons in the emissive layer of the phosphorescent OLED (PhOLED). Thus, the development of stable and high triplet energy hole transport materials is in urgent demand for high-performing PhOLED devices. The present work demonstrates the development of two hetero-arylated pyridines as high triplet energy (2.74-2.92 eV) multifunctional hole transport materials to reduce the exciton quenching and to enhance the extent of charge carrier recombination in the emissive layer. In this regard, we report the design, synthesis, and theoretical modeling with electro-optical properties of two molecules, namely PrPzPy and MePzCzPy, with suitable HOMO/LUMO energy levels and high triplet energy, by incorporating phenothiazine as well as other donating units into a pyridine scaffold, and finally developing a hybrid phenothiazine-carbazole-pyridine based molecular architecture. The natural transition orbital (NTO) calculations were done to analyze the excited state sensation in these molecules. The long-range charge transfer characteristics between the higher singlet and triplet states were also analyzed. The reorganization energy of each molecule was calculated to examine their hole transportability. The theoretical calculations for PrPzPy and MePzCzPy revealed that these two molecular systems could be promising materials for the hole transport layer of OLED devices. As a proof of concept, a solution-processed hole-only device (HOD) of PrPzPy was fabricated. The increase in current density with an increase in operating voltage in the range of ∼3-10 V supported that the suitable HOMO energy of PrPzPy can facilitate the hole transportation from the hole injection layer (HIL) to the emissive layer (EML). These results indicated the promising hole transportability of the present molecular materials.

Polymer synergy for efficient hole transport in solar cells and photodetectors

A new concept “polymer synergy” was introduced to develop versatile dopant-free polymer hole transport materials (HTMs) for optoelectronic devices, including solar cells and photodetectors.

In-situ monitored chemical bath deposition of planar NiO layer for inverted perovskite solar cell with enhanced efficiency

• A solution route of chemical bath deposition (CBD) planar NiO x film was first proposed as the efficient hole transport layer for the inverted PSCs • Through an in-situ monitoring of the CBD reaction process, the morphologies and semiconducting properties of the NiO x film can be adjusted by the concentration variation of [Ni(H 2 O) x (NH 3 ) 6-x ] 2+ cation. • The devices based on planar NiO x at 50°C and C0.5 concentration achieved an enhanced efficiency to from 16.14% to 18.17%. As a convenient, low-cost and up-scalable solution route, chemical bath deposition (CBD) has exhibited impressive advantages in fabricating electron transporting materials like SnO 2 , achieving record efficiencies for regular n-i-p perovskite solar cells (PSCs). However, for the hysteresis-free and potentially more stable inverted p-i-n PSCs, CBD processing is rarely studied to improve the device performance. In this work, we first present a CBD planar NiO x film as the efficient hole transport layer for the inverted perovskite solar cells (IPSCs). The morphologies and semiconducting properties of the NiO x film can be adjusted by varying the concentration of [Ni(H 2 O) x (NH 3 ) 6- x ] 2+ cation via in-situ monitoring of the CBD reaction process. The characterizations of ultraviolet photoelectron spectroscopy, transient absorption spectroscopy, time-resolved photoluminescence suggest that the CBD planar NiO x film possesses enhanced conductivity and aligned energy band levels with perovskite, which benefits for the charge transport in the IPSCs. The devices based on planar NiO x at 50°C and low nickel precursor concentration achieved an enhanced efficiency from 16.14% to 18.17%. This work established an efficient CBD route to fabricate planar NiO x film for PSCs and paved the way for high performance PSCs with CBD-prepared hole transporting materials.

Graphene oxide modified PEDOT:PSS as an efficient hole transport layer for enhanced performance of hybrid silicon solar cells

In recent years, PEDOT:PSS/n-Silicon (n-Si) based hybrid solar cells (HSCs) have drawn a significant attention as promising alternative to the conventional Si solar cell technology. However, poor electrical performance of the PEDOT:PSS limits the power conversion efficiency (PCE) of the device. Herein, tailoring the properties of the PEDOT:PSS via graphene oxide (GO) is investigated to use PEDOT:PSS-GO as an efficient hole transport layer (HTL) for the enhanced performance of the PEDOT:PSS/n-Si HSCs. A small amount of GO incorporation resulted in significantly improved structural, electrical, Si surface passivation properties of the PEDOT:PSS and hence the photovoltaic performance of the PEDOT:PSS-GO/n-Si HSCs. The study reveals that the oxygen functional groups on 2D-GO sheets interact with PEDOT:PSS and facilitates the improved electrical conductivity by >2 folds without affecting its optical properties. Further, the effective passivation of n-Si surface by the composite film has been found with enhanced minority carrier lifetime (∼1.7 folds). The PEDOT:PSS-GO/n-Si HSCs could achieve the highest PCE of 11.22% on device dimension of 1 cm2, which is absolute ∼4.14% higher with respect to that with the pristine PEDOT:PSS. The improved performance is attributed to the effective charge transport properties of the PEDOT:PSS-GO, interface passivation and thus efficient separation and collection of the photo-carriers for an optimum GO addition. The study establishes that PEDOT:PSS-GO composite could be used as an effective HTL for the efficient PEDOT:PSS/n-Si HSCs.

Back Cover Image

AbstractThis cover (DOI: 10.1002/inf2.12345) shows a multifunctional TPA‐azaBODIPY‐TPA small molecule with superior optoelectronic and photophysical properties. Material is shown to function as an efficient hole transport layer in perovskite solar cells reaching a power conversion efficiency of 17.4%, and as a robust electron donor in near‐infrared organic photodetectors absorbing light in the wavelength range of up to 800 nm. Offering two distinct optoelectronic functions, TPA‐azaBODIPY‐TPA is particularly attractive as it enables multi‐purpose applications while maintaining the ease of fabrication. image

Enabling Donor: Acceptor Bicontinuous Networks via Short Contacts in Double‐Cable Polymers with Pendant Rylene Diimides

Double‐cable polymers (DCPs) with donors and acceptors in the same molecular matrix exhibit excellent stability and have great potential in the practical application of organic solar cells (OSCs). However, such chemical structures of DCPs make the morphology and charge transport very complicated. Here, the packing structures and charge transport channels are revealed for the DCPs with pendant acceptors of rylene diimides. Because of strong π–π overlap, the number of neighboring acceptors is limited and the acceptors cannot form a percolation network for electron transport. Importantly, introducing twisted dimeric rylene diimides can significantly increase the number of neighbors and connectivity for the acceptors via short contacts. Moreover, donor:acceptor bicontinuous networks can be achieved by tuning the dimerization ratio. This opens an avenue toward independent, efficient hole, and electron transport for efficient DCP‐based OSCs.