Electron Injection Capability Research Articles

Enhanced Efficiency of Dye-Sensitized Solar Cells by Controlled Co-Adsorption Self-Assembly of Dyes.

Single dyes typically exhibit limited light absorption in dye-sensitized solar cells (DSSCs). Thus, cosensitization using two or more dyes to enhance light-harvesting efficiency has been explored; however, the aggregation of dyes can adversely affect electron injection capabilities. This study focused on the design and synthesis of three dyes with a common carbazole donor for DSSCs: DZ102, TZ101, and JM102. JM102 broadens the absorption spectrum by replacing the benzoic acid electron acceptor of TZ101 with acetylenic benzoic acid. A cosensitized DSSC device based on CO-1 [DZ102:TZ101 = 1:1 (50 μM:50 μM)] achieved a short-circuit current density of 19.4 mA/cm2 and a power conversion efficiency of 10.9%. For the first time, the molecular interactions between the dyes in the photoanode were demonstrated using cyclic voltammetry, which revealed the presence of intermolecular forces. Adsorption kinetics further indicated that these forces promoted the self-assembly of dyes during adsorption, which resulted in a cosensitization adsorption amount greater than the sum of the individual dye adsorptions. This study provides novel insights into the selection of cosensitizing dyes for DSSCs.

DFT simulations of photovoltaic parameters of dye‐sensitized solar cells with new efficient sensitizer of indolo[3, 2‐b]carbazole complexes

AbstractDeveloping economical and high‐performing sensitizers is crucial in advancing dye‐sensitized solar cells (DSSCs) and optoelectronics. This research paper explores the potential of novel red light‐absorbing organic dyes based on Indolo[3,2‐b]carbazole (ICZ) as the donor applied in co‐sensitizer‐free DSSCs for breakthroughs in photovoltaic (PV) applications. DFT and TD‐DFT based computational methods were employed to calculate the conduction band levels, electron injection capabilities, and power conversion efficiency (PCE) of metal‐free organic dyes (ICZ1–ICZ9) having D‐A‐π‐A architecture. Comprehensive analyses included NBO, DOS, FMO, ICT, MEP, binding energy, and TDM analysis. Quantum chemical calculations of the structural, photochemical, and electrochemical properties, as well as the key parameters, reveals that all the designed dyes could be an excellent candidate for high‐efficiency DSSCs due the small energy gap (2.130–1.947 eV), longer wavelength absorption (759.47–520.63 nm), longer lifetimes (15.65–6.67 ns), a lower ΔGreg (0.29–0.14 eV), a significant dipole moment changes (31.489–16.195D), LHE (0.95‐0.46), the large qCT (0.962–0.689), small DCT (7.657, 4.897 Å), and VOC (1.13–0.86 eV). This quantum simulation showed that, when compared to reference D8, the photovoltaic dyes ICZ8, ICZ2, and ICZ7 are recognized as being eye‐catching. Furthermore, dye@(TiO2)9 cluster model results demonstrate promising prospects for enhancing the photovoltaic (PV) performance of ICZ1–ICZ9 dyes by electron injection and conduction band (CB) engineering. This study will help the experimentalists for developing ICZ‐based PVs as more efficient and sustainable energy solutions.

Porous PbBr2 films modulation by indium tribromide additive for the fabrication of SnO2-based CsPbBr3 perovskite solar cells

The achievement of complete conversion of PbBr2 films presents a significant challenge in the development of CsPbBr3 films with consistent growth, comprehensive coverage, and controllable components. To address this challenge, introducing a porous structure in the planar PbBr2 film is advantageous for facilitating the immersion of CsBr precursor, thereby reducing impurity phase formation and mitigating strain caused by the film volume expansion. In order to accomplish this, indium tribromide (InBr3) was employed as an additive and the InBr3(DMF)3 adduct was utilized to expedite the release of organic molecules in PbBr2(DMF), resulting in the transformation of planar PbBr2 film into porous structures. The growth orientation of PbBr2 crystals was altered by this transformation, effectively suppressing the generation of metallic Pb impurities in the film. Additionally, it not only optimizes the morphology of CsPbBr3 film but also reduces impurity phase. As a result, the InBr3:CsPbBr3 perovskite solar cell achieved an efficiency of 7.28 %. The majority of In3+ ions were concentrated near the buried interface between SnO2 and InBr3:CsPbBr3, leading to significant improvements in both non-radiative recombination defect states within the perovskite film and electron injection and collection capabilities within the device.

Substituent effect on the electronic and optical properties of newly designed pyrrole derivatives using density functional theory

Abstract This work explores six newly designed compounds obtained by several substitutions in 2,5-di(2-thienyl) pyrrole molecule. For this series of compounds, the electronic and optical properties were investigated using density functional theory and time-dependent density functional theory (TD-DFT). The new compounds were characterized by calculating the chemical parameters that correlated with their optical and electrical properties. The lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) energies are calculated using the B3LYP functional with the 6-311G (d, p) basis set. The most low-lying energy level of the LUMO was found for Perr-NO2, indicating its effective electron injection capabilities and oxidation resistance. The HOMO and LUMO distributions of Perr-Cl and Perr-NO2 displayed a remarkable complementarity throughout each component of the two compounds, indicating an effective intermolecular charge transfer. The molecular electrostatic potential analysis demonstrated that the proposed compounds have a broad distribution of electrophilic and nucleophilic sites, which predict a high degree of chemical reactivity. The electron density analysis at the bonding and anti-bonding sites of the title compounds was performed using the electron localization function and local orbital locator techniques. Non-covalent interaction analysis using the reduced density gradient approach classified all types of interaction: repulsive, weak, and attractive interactions within compound fragments. All compounds exhibited a robust repulsive interaction, as proved by the red spikes at 0.038 a.u. The ultraviolet/visible (UV/vis) spectrum was obtained by TD-DFT using CAM-B3LYP models in conjunction with 6-311G (d, p) basis set and methanol as a solvent, the absorption bands were found within the UV range, and the maximum wavelength showed red-shifted increases. These compounds could serve as a base material for developing selective gas sensors with considerable UV/vis absorption (180–400 nm). According to the research results, the designed compounds are good candidates for use as precursors in polymer designs for optoelectronic and sensor applications due to their high electrical conductivity and photochemical properties.

Solution processed PANI-rGO-SiO2 nanocomposite with inflated electron injection and transport capabilities as ETL for OLED applications

PANI-rGO-SiO2 nanocomposite as an ETL with varying concentrations of SiO2 was synthesized via oxidative in-situ polymerization process. Their structural and optical properties were investigated by XRD, FESEM, FTIR, Photoluminescence and UV–Vis. Spectroscopy. The PANI depicted a nanofiber-like structure with uniform distribution. The optical band gap of the optimized PGS1 nanocomposite was estimated ∼ 3.01 eV in the visible region of electromagnetic spectrum. TGA results revealed lesser weight loss ∼ 12 % in case of PGS1 nanocomposite than PANI. The light absorption was found at 481 nm in blue region due to charge transfer of SiO2 and PANI-rGO matrix. The current density of PGS1 nanocomposite was observed 76 % greater than pristine PANI using J-V characteristics which showed greater capacities to transfer electron from cathode into emissive layer. These results elucidate that the optimized PGS1 nanocomposite is a compatible candidate for an electron transport layer (ETL) in OLED applications.

Anomalous efficiency elevation of quantum-dot light-emitting diodes induced by operational degradation

Quantum-dot light-emitting diodes promise a new generation of high-performance and solution-processed electroluminescent light sources. Understanding the operational degradation mechanisms of quantum-dot light-emitting diodes is crucial for their practical applications. Here, we show that quantum-dot light-emitting diodes may exhibit an anomalous degradation pattern characterized by a continuous increase in electroluminescent efficiency upon electrical stressing, which deviates from the typical decrease in electroluminescent efficiency observed in other light-emitting diodes. Various in-situ/operando characterizations were performed to investigate the evolutions of charge dynamics during the efficiency elevation, and the alterations in electric potential landscapes in the active devices. Furthermore, we carried out selective peel-off-and-rebuild experiments and depth-profiling analyses to pinpoint the critical degradation site and reveal the underlying microscopic mechanism. The results indicate that the operation-induced efficiency increase results from the degradation of electron-injection capability at the electron-transport layer/cathode interface, which in turn leads to gradually improved charge balance. Our work provides new insights into the degradation of red quantum-dot light-emitting diodes and has far-reaching implications for the design of charge-injection interfaces in solution-processed light-emitting diodes.

Acid groups decorated bimetal-organic catalyst for advanced oxidation technology at full pH range

As a wastewater treatment technology, the activity of advanced oxidation process (AOPs) is strongly dependent on pH value. Herein, considering the low activity of AOPs under alkaline conditions, the acid organic ligand (nitrilotriacetic acid, NTA) was chosen to design Co-NTA metal-organic catalyst for efficient photo-Fenton reaction at full pH range. The experimental results indicate the acid ligands in Co-NTA offers more·OH that can achieve high activity under alkaline conditions. To further enhance the electron injection ability and redox cycles of Co(II)/Co(III), Ferrocene (Fc) nanoparticles was introduced to form bimetallic organic catalyst Fc-Co-NTA. The mechanism study indicates that the synergistic effect between Co-NTA and Fc promotes the activation of potassium persulfate and improves the stability of the catalyst under extreme pH conditions, while the π-π interaction between TC and Fc-Co-NTA can improve the electron injection capability and accelerate the production of·OH/SO4•-, so as to accelerate the redox cycles of Fe(II)/Fe(III) and Co(II)/Co(III), bringing about prolonged carrier lifetime and better photocatalytic activity. The possible degradation pathway of TC was investigated by Fukui function and LC-MS. A machine learning model is used to optimize the synthesis and photocatalytic parameters of Fc-Co-NTA. This study provides a new design idea to prepare highly efficient and stable photo-Fenton advanced oxidation technology at full pH range.

Effect of the spatial configuration of donors on the photovoltaic performance of co-adsorbent organic dyes formed by Z/E configuration

Molecular modification is an important pathway to explore the highly efficient dyes for dye sensitized solar cells (DSSCs). In this work, three co-adsorbent D-π-A dye sensitizers (L1, L2 and L3) formed by Z/E configuration were prepared by the introduction of 4-methoxyphenyl group into the olefin containing triphenylamine dyes, and their photo-physical absorption, electrochemical properties and photovoltaic performance were systematically investigated. Density functional theory (DFT) calculations have been employed to gain insight into the optimized molecular configuration and electron distribution of dyes L1, L2 and L3, which are further correlated with the experimental results. The results indicated that the 4-methoxyphenyl auxiliary donor brought a molecular Z/E configuration and more electron injection capability, which is beneficial to the prevention of π-π aggregation and good light-capturing capability. The photo-physical absorptions are obviously red-shifted from 441 nm to 451 nm for dye L1 and 462 nm–492 nm for dye L2 compared with their predecessors. Co-adsorbent dye L3 with a cyclic thiourea functionalized triphenylamine donor afforded significantly improved current density (15.83 mA cm−2) and PCE (7.96%).

Molecularly understanding and regulating carrier injection behavior of ETL/perovskite towards high performance PeLEDs

Effectively balancing carrier injection of perovskite LEDs (PeLEDs) for next-generation display and illumination urgently needs for molecularly understanding carrier injection behavior of electron transport layer (ETL)/perovskite toward further developing high performance PeLEDs. Here, we molecularly reveal the electron injection behaviors of PeLEDs by theoretically-experimentally decoupling the electron transport of ETLs and electron injection of TmPyPB/perovskite and TPBi/perovskite. Resulted, the better molecular planarity bridging effect (MPBE) of TmPyPB than TPBi can effectively increase electronic-coupling for the improved electron transport ability and significantly decrease injection barrier for the enhanced electron injection capability, intrinsically leading to a more balanced carrier injection and a less electron accumulation of PeLEDs. Compared to TPBi-based PeLEDs, the TmPyPB-based PeLEDs present the obviously-increased average EQE, current efficiency, power efficiency and luminance by 44 %, 63 %, 43 % and 100 %, respectively. Meanwhile, this PeLED shows a higher voltage tolerance characteristic of 7.5 V than that of TPBi-based PeLEDs (6.25 V). Therefore, this work may provide a fundamental insight into carrier injection behavior of PeLEDs for effectively-regulating its carrier injection balance and further for its greatly-facilitated commercialization.

Graphene‐Based Intrinsically Stretchable 2D‐Contact Electrodes for Highly Efficient Organic Light‐Emitting Diodes (Adv. Mater. 31/2022)

Organic Light-Emitting Diodes Intrinsically stretchable light-emitting diodes (ISOLEDs) are becoming increasingly important for wearable electronics. In article number 2203040, Han-Young Woo, Tae-Woo Lee, and co-workers report the design of highly efficient ISOLEDs that use a graphene-based 2D-contact stretchable electrode. As a benefit of a newly designed conjugated polyelectrolyte with efficient electron injection capability, the ISOLED yields an unprecedently high current efficiency of 20.3 cd A−1.

Theoretical approach for Fe(II/III) and its chlorophyll-related complexes as sensitizers in dye-sensitized solar cells

Dye is the key to the efficiency of harvesting solar energy in dye-sensitized solar cells (DSSCs). The dye performances such as light absorption, electron injection, and electron regeneration depend on the dye molecule structure. To predict it, one needs to compute the optimized molecule geometry, HOMO level, LUMO level, electron density distribution, energy gaps, and dipole moment in the ground and excited state. Chlorophyll-related chlorin and porphyrin, as well as their κ2O,O’ complexes with Fe(II/III), were investigated with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) computations using the B3LYP method and def2-TZVP basis set. NPA charges also were calculated to know the valence of the metal cations exactly. In general, the calculations show that the metal cations introduced occupied d orbitals with lower oxidation potentials than the chlorophyll ligand orbitals, which are responsible for the emergence of additional absorption bands. The states result in effective band broadening and the redshift of spectrum absorbance that is expected to improve DSSC performance.
 Another requirement that has to be possessed is the ability of electron regeneration, electron injection, and dipole moment. The Fe(II) complex has fulfilled these requirements, but not the Fe(III) complex due to having a low electron injection capability. However, this work has shown that Fe(III) complex exhibits a non-innocence ligand. It results in trivalent to divalent state change, in the appearance of a ligand radical cation, an extra hole, and a broader absorption spectrum. It also can affect its other electronic properties, such as electron injection capability. Thus, it can be considered an attractive candidate for the sensitizer in DSSCs

Efficient NIR Perovskite Light-Emitting Diodes Enabled by Incorporating an Anthracene Derivative as a Bifunctional Electron Transport Layer

Exploring multifunctional charge transport materials with well-matched energy-levels alignment and compatible interfaces is deemed a potential approach toward high-performance perovskite light-emitting diodes (PeLEDs). Herein, an anthracene derivative, 1-[4-(10-[1,1′-biphenyl]-4-yl-9-anthracenyl)phenyl]-2-ethyl-1H-benzimidazole (BAEBi), is demonstrated as an efficient electron tranport layer (ETL) as well as an effective surface passivation agent for near-infrared (NIR) quasi two-dimensional (Q-2D) PeLEDs. Owing to the promising electron injection and transport capability of BAEBi, an improved charge-carrier balance is attained in rather hole-dominant PeLEDs. Meanwhile, BAEBi assisted to significantly mitigate the perovskite/ETL interfacial defects, rendering a pinhole-free smooth film with quite low roughness and ameliorated exciton lifetime. Consequently, BAEBi-containing NIR Q-2D PeLEDs manifested a low turn-on voltage of 2.5 V with a decent external quantum efficiency (EQE) of 9.2% and a peak radiance of 127 W sr–1 m–2; these values are, respectively, ∼1.5- and 15-fold higher compared to that of a commonly used ETL, 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi). Importantly, the BAEBi-incorporating champion PeLED exhibited significantly curtailed efficiency roll-off and prolonged operational stability. These findings reveal an ingenious solution to address the charge imbalance issue and suppress the interfacial defects in PeLEDs that would spur further development of this emerging technology toward efficient solid-state lighting and high-resolution displays.

On the impact of a metal-insulator-semiconductor structured n-electrode for AlGaN-based DUV LEDs.

In this work, a 280 nm AlGaN-based deep ultraviolet light-emitting diode (DUV LED) with a metal-insulator-semiconductor (MIS) structured n-electrode is fabricated and studied. The SiO2 insulator layer is adopted to form the MIS structure by using an atomic layer deposition system. After adopting the MIS-structured n-electrode, the SiO2 intermediate layer enables electron affinity for the contact metal to be higher than the conduction band of the n-AlGaN layer, which favors the electrons to be injected into the n-AlGaN layer by intraband tunneling rather than thermionic emission. Moreover, the thin SiO2 insulator can share the applied bias, which makes the n-AlGaN layer surface less depleted and thus further facilitates the electron injection. The improved electron injection capability at the metal-semiconductor interface helps reduce the contact resistance and increase electron concentration in the active region, which then improves external quantum efficiency and wall-plug efficiency for the proposed DUV LED.

Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2: Experimental and Computational Studies.

The absence of a secure long-term sustainable energy supply is recognized as a major worldwide technological challenge. The generation of H2 through photocatalysis is an environmentally friendly alternative that can help solve the energy problem. Thus, the development of semiconductor materials that can absorb solar light is an attractive approach. TiO2 has a wide bandgap that suffers from no activity in the visible spectrum, limiting its use of solar radiation. In this research, the semiconductor absorption profile was extended into the visible region of the solar spectrum by preparing porphyrin-TiO2 (P-TiO2) composites of meso-tetra(4-bromophenyl)porphyrin (PP1) and meso-tetra(5-bromo-2-thienyl)porphyrin (PP2) and their In(III), Zn(II) and Ga(III) metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed on the porphyrins to gain insight into their electron injection capability. The results demonstrate that P-TiO2 systems merit further in-depth study for applications that require efficient photocatalytic H2 generation.

Efficient inverted organic light-emitting devices using a charge-generation unit as electron-injection layers

Efficient electron injection from cathode to electron transport layer is generally required to realize high-performance inverted organic light-emitting devices (IOLEDs). In this work, highly efficient IOLEDs are developed by employing a non-doped charge-generation unit of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN)/Al/LiF as electron-injection layers (EILs). The ultraviolet photoelectron spectroscopy (UPS) shows that the insertion of HAT-CN layer reduces the work function of EILs by 0.21 eV. Combined with the current-voltage characteristics of electron-only devices, the role of the HAT-CN layer in promoting electron injection is confirmed. What's more, the double EILs device with Rubrene as a probe verifies the strong hole blocking ability of HAT-CN/Al/LiF. Based on the EILs, the inverted blue phosphorescent OLEDs with a maximum current efficiency of 29.4 cd/A are realized. The excellent performance proves the superiority of HAT-CN/Al/LiF as EILs. Working diagrams of CGU as EILs.In this work, highly efficient IOLEDs are developed by employing a non-doped CGU of HAT-CN/Al/LiF as EILs. The EILs show strong electron injection and hole blocking capabilities. •The charge generation unit as the electron injection layers greatly improves the injection of electrons. •The non-doped electron injection layers improves the stability and repeatability of the devices. •Based on the EILs, the inverted blue OLEDs with the maximum current efficiency of 29.4 cd/A and a maximum EQE of 14.6% are realized.

Experimental and computational study on electronic and photovoltaic properties of chromen-2-one-based organic dyes used for dye-sensitized solar cells

In the present work, three dyes of 6,7-dihydroxy-8-[(E)-(4-methoxyphenyl)diazenyl]-4-methyl-2H-chromen-2-one, (D1) 6,7-dihydroxy-8-[(E)-(4-hydroxyphenyl) diazenyl]-4-methyl-2H-chromen-2-one (D2), and 6,7-dihydroxy-4-methyl-8-[(E)-(4-methylphenyl) diazenyl]-2H-chromen-2-one (D3) were experimentally tested as photosensitizer in solar cell. and a computation study was conducted to explain the efficiency of these compounds as photo-sensitizer in a solar cell. The polarizability (<α > ), the anisotropy of the polarizability (<Δα > ), ground-state dipole moment (µ) and the first-order hyperpolarizability (β) of the dyes were studied at Density Functional Theory (DFT) using Gaussian 09 and Gauss View v.6.0 based on keywords: “opt freq b3lyp/6-311G++(d,p) guess = mix pop=(nbo, savenbos) geom = connectivity polar = optrot. Also, EHOMO (the highest occupied molecular orbital energy), ELUMO (the lowest unoccupied molecular orbital energy), HOMO-LUMO energy gap (ΔE), electron affinity (A), and ionization potential are investigated. The calculation based on the structure modification of the dyes with electron-withdrawing groups (HO-C and CH3-O-C) and electron repelling group (H3C-C) based on a push-pull framework of Qumarin was studied. The simulations indicate that the improvement of Qumarin-based dyes can reduce the energy gap and produce a redshift. This structural modification also improves the light-capturing and the electron injection capability, making it excellent in photoelectric conversion efficiency (PCE). This structural modification also improves the light-capturing and the electron injection capability, making it excellent in photoelectric conversion efficiency (PCE).

Efficient halide perovskite light-emitting diodes with emissive layer consisted of multilayer coatings

Perovskite light-emitting diodes (PeLEDs) with multilayer coatings consisted of CsPbBr3 and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene as the emissive layer are demonstrated. The effects of the multilayer coatings upon both the electroluminescent performance and the device stability are investigated. The PeLEDs with a coating pair number of 4 (four-pair PeLEDs) obtain a maximum current efficiency of 9.16 cd/A and a maximum external quantum efficiency of 2.37%, corresponding to more than 4-fold enhancement to those of the control PeLEDs. Furthermore, the half-lifetime of the four-pair PeLEDs is about 50 times longer than that of the control PeLEDs. Such enhancements are attributed to the improved film morphology, enhanced electron injection and transport capability, widened exciton formation zone, and better exciton confinement.

2-Methyl-9,10-bis(naphthalen-2-yl)anthracene doped rubidium carbonate as an effective electron injecting interlayer on indium-tin oxide cathode in inverted bottom-emission organic light-emitting diodes

2-Methyl-9,10-bis(naphthalen-2-yl)anthracene doped rubidium carbonate (MADN:Rb2CO3) is used as an effective electron injecting interlayer on an indium-tin oxide (ITO) cathode for inverted bottom-emission organic light-emitting diodes (IBOLEDs). At a Rb2CO3 doping concentration of 20% in MADN, the device exhibits enhanced characteristics, some of which are turn-on voltage, luminance at a given current density, and current efficiency. The attained performance is better than that of the device using lithium fluoride (LiF) as an n-type dopant. Space-charge-limited current acknowledges improved electrical properties of Rb2CO3 doped MADN. Ultraviolet and X-ray photoelectron spectroscopy investigation unveils an interfacial dipole layer induced by charge transfer between Rb2CO3 and ITO, leading to a lowered ITO work function and an electron injection barrier. The improved electron injection and transport capabilities contribute to better charge balance in IBOLED, thus resulting in advanced luminance efficiency. In addition, the morphology stability of organic films is also amended, which benefits long-term reliability under operationally induced thermal stress. Moreover, the effectiveness of using Rb2CO3:MADN as an electron injecting layer for IBOLEDs is superior to many of its alkali-based counterparts demonstrated in the literature, with high compatibility with different types of sophisticated ITO-based IBOLEDs.

Computational Prediction of Electronic and Photovoltaic Properties of Anthracene-Based Organic Dyes for Dye-Sensitized Solar Cells

Three kinds of anthracene-based organic dyes for dye-sensitized solar cells (DSSCs) were studied, and their structures are based on a push–pull framework with anthracenyl diphenylamine as the donor connected to a carboxyphenyl or carboxyphenyl-bromothiazole (BTZ) as the acceptor via an acetylene bridge. The photoelectric properties of the three dyes were investigated using density functional theory (DFT). The simulations indicate that the improvement of anthracene-based dyes (the addition of BTZ and the change of alkyl groups to alkoxy chains) can reduce the energy gap and produce a red shift. This structural modification also improves the light capturing and the electron injection capability, making it excellent in photoelectric conversion efficiency (PCE). In addition, twelve molecules have been designed to regulate photovoltaic performance.

Barium hydroxide hole blocking layer for front- and back-organic/crystalline Si heterojunction solar cells

We demonstrate the potential of barium hydroxide, Ba(OH)2, as a hole blocking layer on the photovoltaic performance of front- and back-organic/n-type crystalline silicon (n-Si) heterojunction solar cells with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS). The power conversion efficiency (PCE) of the front-PEDOT:PSS/n-Si heterojunction solar cell was increased from 12.8% for pristine to 13.6% with a 2-nm-thick Ba(OH)2 interlayer at the rear n-Si and aluminum (Al) cathode interface due to the enhanced hole blocking as well as electron injection capability to the Al cathode in the infrared region. PCE was further increased to 14.3% with a short-circuit density JSC of 30.27 mA/cm2, an open-circuit voltage VOC of 0.632 V, and a fill factor FF of 0.75 using a 20-nm-thick 4,4′-Cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] as an antireflection layer. PCE of the back-PEDOT:PSS/n-Si heterojunction solar cells was also increased from 4.4% for pristine to 8.1% with a JSC of 33.40 mA/cm2, a VOC of 0.573 V, and an FF of 0.423 by inserting a 2-nm-thick Ba(OH)2 layer at the front-Al and isotropically textured n-Si interface. These findings imply that Ba(OH)2 has great potential as an efficient hole-blocking layer for both front- and back-PEDOT:PSS/n-Si heterojunction solar cells.