Size-dependent scattering efficiency in dye-sensitized solar cell

Effect of scattering particle size on light scattering efficiency in dye-sensitized solar cell has been investigated with a FTO/semitransparent nano-TiO₂ layer (main-layer)/scattering layer (overlayer) structure, where two different rutile TiO₂ particles of 0.3 μm (G1) and 0.5 μm (G2) were used for a scattering overlayer and 20-nm anatase particle for nano-TiO₂ main-layer. The conversion efficiency of 7.55% for the 7 μm-thick main-layer film is improved to 8.94% and 8.78% when G1 and G2 particulate overlayers are introduced, respectively, corresponding to 18.4% and 16.3% increments. While the conversion efficiency of the 14 μm-thick main-layer is slightly improved from 8.60% to 9.09% and 9.15% upon depositing G1 and G2 particulate overlayers, respectively. Significant improvement and strong size-dependence upon deposition of scattering overlayer on the relatively thinner TiO₂ main-layer film are associated with the quantity and wavelength of transmitted light and the difference in reflectivity of G1 and G2 scattering particles.     

Hybrid Dye‐Titania Nanoparticles for Superior Low‐Temperature Dye‐Sensitized Solar Cells

In this work, a new strategy to design low‐temperature (≤200 °C) sintered dye‐sensitized solar cells (lt‐DSSC) is reported to enhance charge collection efficiencies (η_coll), photoconversion efficiencies (η), and stabilities under continuous operation conditions. Realization of lt‐DSSC is enabled by the integration of hybrid nanoparticles based on TiO₂‐Ru(II) complex (TiO₂_Ru_IS)—obtained by in situ bottom‐up construction of Ru(II) N3 dye‐sensitized titania—into the photoelectrode. Incentives for the use of TiO₂_Ru_IS are i) dye stability due to its integration into the TiO₂ anatase network and ii) enhanced charge collection yield due to its significant resistance toward electron recombination with electrolytes. It is demonstrated that devices with single‐layer photoelectrodes featuring blends of P25 and TiO₂_Ru_IS give rise to a 60% η_coll relative to a 46% η_coll for devices with P25‐based photoelectrodes. Responsible for this trend is a better charge transport and a reduced electron recombination. When using a multilayered photoelectrode architecture with a top layer based only on TiO₂_Ru_IS, devices with an even higher η_coll (74%) featuring a η of around 8.75% and stabilities of 600 h are achieved. This represents the highest values reported for lt‐DSSC to date.     

Why Gratzel’s cell works so well

In Gratzel’s cell, the electrons injected by the photo-excitation of dye molecules, anchored to a mesoporous TiO₂ film, efficiently diffuse to the back contact achieving solar energy conversion at efficiencies exceeding 10%. The mesoporous TiO₂ surface constituted of randomly arranged nanocrystallites with a roughness factor of the order 1000 is heavily populated with traps, defects and adsorbed species which act as recombination centers. Nevertheless, the cell functions, mitigating recombination expected to occur via the interaction electrons at the surface. Evidence based mainly on 1/f noise measurements is presented to show that dye bonded to the TiO₂ surface passivates recombination centers. Furthermore the suppression of trapping-detrapping events at the surface increases the diffusion coefficient of the electrons through the nanocrystalline matrix facilitating electron transport to the back contact. The Gratzel cell is also unique, none of the high bandgap oxide materials other than TiO₂ yield energy conversion and quantum efficiencies as high as that of the cells based on TiO₂. 1/f noise measurements also reveal a distinct difference between TiO₂ and ZnO mesoporous films suggesting that the films made from the latter material are more intensely populated with surface states that mediate recombination.     

Recent Progress in Dye‐Sensitized Solar Cells Using Nanocrystallite Aggregates

Nanocrystallite aggregates are spherical assemblies of nanometer‐sized crystallites and feature a size on the order of sub‐micrometers. This paper reports and summarizes recent progress in nanocrystallite aggregates for applications in dye‐sensitized solar cells. It emphasizes that nanocrystallite aggregates are a promising class of materials with the capability to generate light scattering, enhance electron transport, retain high specific surface area for dye adsorption, and facilitate electrolyte diffusion while serving as the photoelectrode film of a dye‐sensitized solar cell. In the Perspectives section, it is suggested that optimization of the porosity of the aggregates, the facets of nanocrystallites forming the aggregates, and the structure of photoelectrode film could possibly lead to breakthroughs in improving the power conversion efficiency of the current state‐of‐the‐art dye‐sensitized solar cells.     

Mesoporous TiO2 Beads Offer Improved Mass Transport for Cobalt‐Based Redox Couples Leading to High Efficiency Dye‐Sensitized Solar Cells

Overcoming ionic diffusion limitations is essential for the development of high‐efficiency dye‐sensitized solar cells based on cobalt redox mediators. Here, improved mass transport is reported for photoanodes composed of mesoporous TiO₂ beads of varying pore sizes and porosities in combination with the high extinction YD2‐o‐C8 porphyrin dye. Compared to a photoanode made of 20 nm‐sized TiO₂ particles, electrolyte diffusion through these films is greatly improved due to the large interstitial pores between the TiO₂ beads, resulting in up to 70% increase in diffusion‐limited current. Simultaneously, transient photocurrent measurements reveal no mass transport limitations for films of up to 10 μm thickness. In contrast, standard photoanodes made of 20 nm‐sized TiO₂ particles show non‐linear behavior in photocurrent under 1 sun illumination for a film thickness as low as 7 μm. By including a transparent thin mesoporous TiO₂ underlayer in order to reduce optical losses at the fluorine‐doped tin oxide (FTO)‐TiO₂ interface, an efficiency of 11.4% under AM1.5G 1 sun illumination is achieved. The combination of high surface area, strong scattering behavior, and high porosity makes these mesoporous TiO₂ beads particularly suitable for dye‐sensitized solar cells using bulky redox couples and/or viscous electrolytes.     

A New Heteroleptic Ruthenium Sensitizer for Transparent Dye‐Sensitized Solar Cells

A new heteroleptic ruthenium complex, coded CYC‐B19 , incorporating an ancillary ligand endowed with hexylthio‐bithiophene segments and a conjugated anchoring ligand with vinyl groups was prepared. This new sensitizer exhibits a lower energy MLCT band centred at 562 nm with a remarkably high molar absorption coefficient of 2.97 × 10⁴ M^?1 cm^?1. DFT‐TDDFT theoretical calculation revealed that insertion a vinyl group in the anchoring ligand pushes the LUMO electron locating more on the anchoring ligand. This will benefit the electron transfer from dye to TiO₂ when the dye molecules were excited by light. Physicochemical measurements and the optimization of electrolyte were done to investigate the potential of CYC‐B19 in TiO₂ scattering‐layer free dye‐sensitized solar cells. Not only is a good photovoltaic efficiency of 8.4% reached, but the transparent device sensitized by CYC‐B19 also presents a superior spectral response to its predecessor CYC‐B11 .     

Triple‐Layer Structured Composite Separator Membranes with Dual Pore Structures and Improved Interfacial Contact for Sustainable Dye‐Sensitized Solar Cells

A composite separator membrane (CSM) with an A/B/A type layered structure, composed of a microporous electrolyte‐philic poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) gel layer (A) and a submicrometer porous polyethylene (PE) or a macroporous poly(ethylene terephthalate) (PET) non‐woven matrix (B), is introduced in a dye‐sensitized solar cell (DSSC). Commercially available PE and PET separator membranes (SMs) act as matrices that provide mechanical stability to the DSSC and permanent pore structures for facilitated ion transport. PVdF‐HFP is used as a microporous gelator for improved interfacial contact between the solid SM and the electrodes. The PVdF‐HFP gel impedes the charge recombination process between electron and I₃ ^? at the TiO₂/electrolyte interface, resulting in improved electron lifetimes. The DSSC assembled with the CSM exhibits high initial solar energy conversion efficiency (η, 6.1%) and stable η values over 1400 h, demonstrating good long term stability. The behaviors of the DSSC are attributed to the synergistic factors of the CSM, such as improved ion conductivity, electrolyte affinity, electrolyte retention capability, effective interfacial contact, and plausible passivation of the dyes. This study demonstrates a practical combination of short‐ and long‐term DSSC performance through the introduction of the CSM.     

Surface‐Plasmon Assisted Energy Conversion in Dye‐Sensitized Solar Cells

In this study, the effect of plasmonic core‐shell structures, consisting of dielectric cores and metallic nanoshells, on energy conversion in dye‐sensitized solar cells (DSSCs) is investigated. The structure of the core‐shell particles is controlled to couple with visible light so that the visible component of the solar spectrum is amplified near the core‐shell particles. In core‐shell particle – TiO₂ nanoparticle films, the local field intensity and light pathways are increased due to the surface plasmons and light scattering. This, in turn, enlarges the optical cross‐section of dye sensitizers coated onto the mixed films. When 22 vol% of core‐shell particles are added to a 5 μm thick TiO₂ film, the energy conversion efficiency of DSSCs increases from 2.7% to 4.0%, in spite of a more than 20% decrease in the amount of dyes adsorbed on the composite films. The correlation between core‐shell particle content and energy conversion efficiency in DSSCs is explained by the balance among near‐field effects, light scattering efficiency, and surface area in the composite films.     

Towards Long‐Term Photostability of Solid‐State Dye Sensitized Solar Cells

The solid‐state dye‐sensitized solar cell (DSSC) was introduced to overcome inherent manufacturing and instability issues of the electrolyte‐based DSSC and progress has been made to deliver high photovoltaic efficiencies at low cost. However, despite 15 years research and development, there still remains no clear demonstration of long‐term stability. Here, solid‐state DSSCs are subjected to the severe aging conditions of continuous illumination at an elevated temperature. A fast deterioration in performance is observed for devices encapsulated in the absence of oxygen. The photovoltaic performance recovers when re‐exposed to air. This reversible behavior is attributed to three related processes: i) the creation of light and oxygen sensitive electronic shunting paths between TiO₂ and the top metal electrode, ii) increased recombination at the TiO₂/organic interface, and iii) the creation of deep electron traps that reduce the photocurrent. The device deterioration is remedied by the formation of an insulating alumino‐silicate shell around the TiO₂ nanocrystals, which reduces interfacial recombination, and the introduction of an insulating mesoporous SiO₂ buffer layer between the top electrode and TiO₂, which acts as a permanent insulating barrier between the TiO₂ and the metal electrode, preventing shunting.     

Hexylthiophene‐Featured D–A–π–A Structural Indoline Chromophores for Coadsorbent‐Free and Panchromatic Dye‐Sensitized Solar Cells

For a sensitizer with a strong π‐conjugation system, a coadsorbent is needed to hinder dye aggregation. However, coadsorption always brings a decrease in dye coverage on the TiO₂ surface. Organic ‘‘D–A–π–A’’ dyes, WS‐6 and WS‐11, are designed and synthesized based on the known WS‐2 material for coadsorbent‐free, dye‐sensitized solar cells (DSSCs). Compared with the traditional D–π–A structure, these D–A–π–A indoline dyes, with the additional incorporated acceptor unit of benzothiadiazole in the π‐conjugation, exhibit a broad photoresponse, high redox stability, and convenient energy‐level tuning. The attached n‐hexyl chains in both dyes are effective to suppress charge recombination, resulting in a decreased dark current and enhanced open‐circuit voltage. Electrochemical impedance spectroscopy studies indicate that both the resistance for charge recombination and the electron lifetime are increased after the introduction of alkyl chains to the dye molecules. Without deoxycholic acid coadsorption, the power‐conversion efficiency of WS‐6 (7.76%) on a 16 μm‐thick TiO₂ film device is 45% higher than that of WS‐2 (5.31%) under the same conditions. The additional n‐hexylthiophene in WS‐11 extends the photoresponse to a panchromatic spectrum but causes a low incident photon‐to‐current conversion efficiency.     

Overcoming Charge Collection Limitation at Solid/Liquid Interface by a Controllable Crystal Deficient Overlayer

Bulk and surface charge recombination of photoelectrode are two key processes that significantly hinder solar‐to‐fuel conversion of photoelectrochemical cell (PEC). In this study, the function of a “crystal‐deficient” overlayer is unveiled, which outperforms a traditionally used amorphous or crystalline overlayer in PEC water splitting by exhibiting a high conductivity and large electron diffusion length to enable unlimited electron collection. The optimized ≈2.5 nm thickness of the “crystal‐deficient” shell results in a depletion layer with a width of 3 nm, which overcomes the flat band limitation of the photovoltage and increases the light absorptivity in the wavelength range from 300 to 420 nm. In addition, a 50‐fold increase in the conductivity yields a one‐order‐of‐magnitude increase in the diffusion length of an electron (L_n )(≈20 μm), allowing for unlimited electron collection in the 1.9 μm TiO₂ nanowire array with the “crystal‐deficient” shell. The controllable “crystal‐deficient” overlayer in rutile TiO₂ nanowires photoanode achieves a photocurrent density greater than 2.0 mA cm^?2 at 1.23 V versus reversible hydrogen electrode (RHE), a 1.18% applied bias photon‐to‐current efficiency at 0.49 V versus RHE, a faradaic efficiency greater than 93.5% at 0.6 V versus Pt under air mass 1.5G simulated solar light illumination (100 mW cm^?2).     

Efficient and Stable TiO2:Pt–Cu(In,Ga)Se2 Composite Photoelectrodes for Visible Light Driven Hydrogen Evolution

Novel thin film composite photocathodes based on device‐grade Cu(In,Ga)Se₂ chalcopyrite thin film absorbers and transparent conductive oxide Pt‐implemented TiO₂ layers on top are presented for an efficient and stable solar‐driven hydrogen evolution. Thin films of phase‐pure anatase TiO₂ are implemented with varying Pt‐concentrations in order to optimize simultaneously i) conductivity of the films, ii) electrocatalytic activity, and iii) light‐guidance toward the chalcopyrite. Thereby, high incident‐photon‐to‐current‐efficiencies of more than 80% can be achieved over the full visible light range. In acidic electrolyte (pH 0.3), the most efficient Pt‐implemented TiO₂–Cu(In,Ga)Se₂ composite electrodes reveal i) photocurrent densities up to 38 mA cm^?2 in the saturation region (?0.4 V RHE, reversible hydrogen electrode), ii) 15 mA cm^?2 at the thermodynamic potential for H₂‐evolution (0 V RHE), and iii) an anodic onset potential shift for the hydrogen evolution (+0.23 V RHE). It is shown that the gradual increase of the Pt‐concentration within the TiO₂ layers passes through an efficiency‐ and stability‐maximum of the device (5 vol% of Pt precursor solution). At this maximum, optimized light‐incoupling into the device‐grade chalcopyrite light‐absorber as well as electron conductance properties within the surface layer are achieved while no degradation are observed over more than 24 h of operation.     

Ligand‐Assisted Assembly Approach to Synthesize Large‐Pore Ordered Mesoporous Titania with Thermally Stable and Crystalline Framework

A novel ligand‐assisted assembly approach is demonstrated for the synthesis of thermally stable and large‐pore ordered mesoporous titanium dioxide with a highly crystalline framework by using diblock copolymer poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) as a template and titanium isopropoxide (TIPO) as a precursor. Small‐angle X‐ray scattering, X‐ray diffraction (XRD), transmission electron microscopy (TEM), high‐resolution scanning electron microscopy, and N₂‐sorption measurements indicate that the obtained TiO₂ materials possess an ordered primary cubic mesostructure with large, uniform pore diameters of about 16.0 nm, and high Brunauer–Emmett–Teller surface areas of ～112 m² g^?1, as well as high thermal stability (～700 °C). High resolution TEM and wide‐angle XRD measurements clearly illustrate the high crystallinity of the mesoporous titania with an anatase structure in the pore walls. It is worth mentioning that, in this process, in addition to tetrahydrofuran as a solvent, acetylacetone was employed as a coordination agent to avoid rapid hydrolysis of the titanium precursor. Additionally, stepped evaporation and heating processes were adopted to control the condensation rate and facilitate the assembly of the ordered mesostructure, and ensure the formation of fully polycrystalline anatase titania frameworks without collapse of the mesostructure. By employing the obtained mesoporous and crystallized TiO₂ as the photoanode in a dye‐sensitized solar cell, a high power‐conversion efficiency (5.45%) can be achieved in combination with the N719 dye, which shows that this mesoprous titania is a great potential candidate as a catalyst support for photonic‐conversion applications.     

Physically Stable Polymer‐Membrane Electrolytes for Highly Efficient Solid‐State Dye‐Sensitized Solar Cells with Long‐Term Stability

A 3D polymer‐network‐membrane (3D‐PNM) electrolyte is described for highly stable, solid‐state dye‐sensitized solar cells (DSCs) with excellent power‐conversion efficiency (PCE). The 3D‐PNM electrolyte is prepared by using one‐pot in situ cross‐linking polymerization on the surface of dye‐sensitized TiO₂ particles in the presence of redox species. This method allows the direct connection of the 3D‐PNM to the surface of the TiO₂ particles as well as the in situ preparation of the electrolyte gel during device assembly. There are two junction areas (liquid and solid‐state junctions) in the DSCs that employ conventional polymer electrolytes, and the major interface is at the liquid‐state junction. The solid‐state junction is dominant in the DSCs that employ the 3D‐PNM electrolyte, which exhibit almost constant performance during aging at 65 °C for over 700 h (17.0 to 17.2 mA cm^–2). The best cell performance gives a PCE of 9.1%; this is slightly better than the performance of a DSC that employs a liquid electrolyte.     

Thin Film Co3O4/TiO2 Heterojunction Solar Cells

Co₃O₄ is investigated as a light absorber for all‐oxide thin‐film photovoltaic cells because of its nearly ideal optical bandgap of around 1.5 eV. Thin film TiO₂/Co₃O₄ heterojunctions are produced by spray pyrolysis of TiO₂ as a window layer, followed by pulsed laser deposition of Co₃O₄ as a light absorbing layer. The photovoltaic performance is investigated as a function of the Co₃O₄ deposition temperature and a direct correlation is found. The deposition temperature seems to affect both the crystallinity and the morphology of the absorber, which affects device performance. A maximum power of 22.7 μW cm^?2 is obtained at the highest deposition temperature (600 °C) with an open circuit photovoltage of 430 mV and a short circuit photocurrent density of 0.2 mA cm^?2. Performing deposition at 600 °C instead of room temperature improves power by an order of magnitude and reduces the tail states (Urbach edge energy). These phenomena can be explained by larger grains that grows at high temperature, as opposed to many nucleation events that occur at lower temperature.     

TiO2 Nanocrystals Synthesized by Laser Pyrolysis for the Up‐Scaling of Efficient Solid‐State Dye‐Sensitized Solar Cells

A crucial issue regarding emerging nanotechnologies remains the up‐scaling of new functional nanostructured materials towards their implementation in high performance applications on a large scale. In this context, we demonstrate high efficiency solid‐state dye‐sensitized solar cells prepared from new porous TiO₂ photoanodes based on laser pyrolysis nanocrystals. This strategy exploits a reduced number of processing steps as well as non‐toxic chemical compounds to demonstrate highly porous TiO₂ films. The possibility to easily tune the TiO₂ nanocrystal physical properties allows us to demonstrate all solid‐state dye‐sensitized devices based on a commercial benchmark materials (organic indoline dye and molecular hole transporter) presenting state‐of‐the‐art performance comparable with reference devices based on a commercial TiO₂ paste. In particular, a drastic improvement in pore infiltration, which is found to balance a relatively lower surface area compared to the reference electrode, is evidenced using laser‐synthesized nanocrystals resulting in an improved short‐circuit current density under full sunlight. Transient photovoltage decay measurements suggest that charge recombination kinetics still limit device performance. However, the proposed strategy emphasizes the potentialities of the laser pyrolysis technique for up‐scaling nanoporous TiO₂ electrodes for various applications, especially for solar energy conversion.     

A Hierarchically Organized Photoelectrode Architecture for Highly Efficient CdS/CdSe‐Sensitized Solar Cells

A form of photoelectrode architecture suitable for inorganic semiconductor solar cells is reported. The developed architecture consists of hierarchically organized TiO₂ nanostructures with several tens of nanometer‐sized particles that have a large surface area and open channels with several hundred‐nanometer‐gaps perpendicular to the substrate. These are tailored by controlling the kinetic energy of the ablated species during pulsed laser deposition (PLD). To fabricate the solar cells, CdS and CdSe inorganic sensitizers are assembled onto the architecture by successive ionic layer adsorption and reaction and polysulfide solution is used as an electrolyte with lead sulfide counter‐electrodes. The inorganic semiconductor solar cells using the developed architecture (PLD‐TiO₂) show high energy conversion efficiencies of 5.57% compared to a conventional mesoporous TiO₂ film(NP‐TiO₂) (3.84%) with an optical mask at 1 sun of illumination. The improved cell performance of PLD‐TiO₂ is attributed to greater light‐harvesting ability, which results in the enhancement of the J_sc value. PLD‐TiO₂ absorbs more CdS/CdSe because of its larger surface area and excellent adhesion properties with fluorine‐doped tin oxide (FTO) substrates. Additionally, due to its unique channel‐shaped architecture, PLD‐TiO₂ has a longer electron lifetime compared to NP‐TiO₂.     

Dominating Energy Losses in NiO p‐Type Dye‐Sensitized Solar Cells

Nickel oxide based p‐type dye‐sensitized solar cells (DSCs) are limited in their efficiencies by poor fill factors (FFs). This work explores the origins of this limitation. Transient absorption spectroscopy identifies fast recombination between the injected hole and the dye anion under applied load as one of the predominant reasons for the poor FF of NiO‐based DSCs. A reduced hole injection efficiency, η_INJ, under applied load is found to play an equally important role. Both, the dye regeneration yield, Φ_REG, and η_INJ decrease by approximately 40%–50% when moving from short‐ to open‐circuit conditions. Spectroelectrochemical measurements reveal that the electrochromic properties of NiO are a further limiting factor for the device performance leading to variable light‐harvesting efficiencies, η_LH, under applied load. The peak light‐harvesting efficiency decreases from 63% at short circuit to 57% at 600 mV reducing the FF of NiO DSCs by 5%. This effect is expected to be more pronounced for future devices with higher operating voltages. Incident, photon‐to‐electron conversion efficiency front–back analysis at applied bias is utilized to characterize the interfacial charge recombination. It is found that the recombination between the injected hole and the redox mediator has a surprisingly small effect on the FF.     

Photocatalytic Reduction of CO2 into Methanol over Ag/TiO2 Nanocomposites Enhanced by Surface Plasmon Resonance

Ag-loaded TiO₂ (Ag/TiO₂) nanocomposites were prepared by microwave-assisted chemical reduction method using tetrabutyl titanate as the Ti source. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption–desorption isotherms, UV–vis absorption spectrum, X-ray photoelectron spectrum, photoluminescence spectrum, and Raman scattering spectrum, respectively. Results revealed that Ag nanoparticles (NPs) were successfully deposited on TiO₂ by reduction of Ag⁺, and the visible light absorption and Raman scattering of TiO₂ were enhanced by Ag NPs based on its surface plasmon resonance effect. Besides, Ag NPs could also effectively restrain the recombination of photogenerated electrons and holes with a longer luminescence life time. In addition, photocatalytic reduction of CO₂ with H₂O on the composites was conducted to obtain methanol. Experimental results indicated that Ag-loaded TiO₂ had better photocatalytic activity than pure TiO₂ due to the synergistic effect between UV light excitation and surface plasmon resonance enhancement, and 2.5 % Ag/TiO₂ exhibited the best activity; the corresponding energy efficiency was about 0.5 % and methanol yield was 405.2 μmol/g-cat, which was 9.4 times higher than that of pure TiO₂. Additionally, an excitation enhancement synergistic mechanism was proposed to explain the experimental results of photocatalytic reduction of CO₂ under different reaction conditions.     

Interfacial Modification Using Hydrogenated TiO2 Electron‐Selective Layers for High‐Efficiency and Light‐Soaking‐Free Organic Solar Cells

Optimizing the interfacial contacts between the photoactive layer and the electrodes is an important factor in determining the performance of organic solar cells (OSCs). A charge‐selective layer with tailored electrical properties enhances the charge collection efficiency and interfacial stability. Here, the potential of hydrogenated TiO₂ nanoparticles (H‐TiO₂ NPs) as an efficient electron‐selective layer (ESL) material in OSCs is reported for the first time. The H‐TiO₂ is synthesized by discharge plasma in liquid at atmospheric pressure, which has the benefits of a simple one‐pot synthesis process, rapid and mild reaction conditions, and the capacity for mass production. The H‐TiO₂ exhibits high conductivity and favorable energy level formation for efficient electron extraction, providing a basis for an efficient bilayer ESL system composed of conjugated polyelectrolyte/H‐TiO₂. Thus, the enhanced charge transport and extraction efficiency with reduced recombination losses at the cathode interfacial contacts is achieved. Moreover, the OSCs composed of H‐TiO₂ are almost free of light soaking, which has been reported to severely limit the performance and stability of OSCs based on conventional TiO₂ ESLs. Therefore, H‐TiO₂ as a new efficient, stable, and cost‐effective ESL material has the potential to open new opportunities for optoelectronic devices.