Conventional Organic Solar Cells Research Articles

Organic solar cell efficiency improvement through architecture engineering by integrating carbon nanoring – SCAPS 1D modelling

This research work aims to investigate on improving the performance of organic solar cells (OSC) by proposing new architectures that progressively integrate carbon nanotubes. This contribution takes into account the exceptional properties of carbon nanotubes (CNT) highlighted in recent work, with the aim of addressing the current challenges of materials used in the manufacture of conventional OSCs, such as reactivity with the ambient medium, stability over time, better transport of charge carriers, etc. Using a reference OSC cell with the following structure: PEDOT/BHJ/PDINO and the numerical one-dimensional simulation tool SCAPS, which helps in validating the modelling approach, we gradually replace each layer with a CNT-based material exhibiting superior properties. In this respect, we carry out calculations on the different cells architectures, to better visualize energy-level alignment profiles, the different current-voltage (J-V), and quantum efficiency (QE) characteristics. Approaches toward efficiency improvement were discussed, by investigating the effects of active layer thickness, the doping level, the charge carriers mobility, defect density, and external parameters such as temperature. After numerous calculations and modelling, very promising results were finally achieved with a full CNT-based solar structure with the following recorded performances: VOC=0.87V, JSC=27.81mA/cm2, FF=80.91%, and PCE=19.63%. These results are the first theoretical report for a complete CNT-based modelled OSC and, given the reliability and robustness of the approach adopted, they can be considered as relevant for future theoretical and experimental work. The integration of CNT as functional layers is a remarkable step forward in OSC architectures engineering for efficiency enhancement. CNT are good candidates for light harvesting applications.

Brominated Quaternary Ammonium Salt-Assisted Hybrid Electron Transport Layer for High-Performance Conventional Organic Solar Cells.

Interlayer engineering is crucial for achieving efficient and stable organic solar cells (OSCs). Herein, by introducing a commercialized brominated quaternary ammonium salt, hexamethonium bromide (HB), into a perylene diimide (PDI)-structured electron transport layer (ETL), a PDINN:HB hybrid ETL with enhanced charge collection ability and environmental/operational stability is realized. Molecular dynamics simulations and Kelvin probe force microscopy indicate that strong polar bromine and amine groups can form extra interfacial dipoles in the hybrid interlayer, while X-ray photoelectron spectroscopy and electron paramagnetic resonance suggest the hybrid ETL can interact with the Ag cathode, thereby regulating the energy level arrangement at the interface. As for the results, the PDINN:HB hybrid ETL enables improved power conversion efficiency (PCE) from 17.8 to 18.4% and 18.8 to 19.4% in PM6:C5-16 bulk heterojunction- and PM6/L8-BO pseudobulk heterojunction-based OSCs, respectively. The versatility of this method is further verified by introducing a range of brominated quaternary ammonium salts into PDINN, in which a superior PCE and stability are all obtained compared to the reference device.

Fast-Growth Polymer: Fullerene Bulk-Heterojunction Thin Films for Efficient Organic Photovoltaics.

The bulk-heterojunction (BHJ) system that uses a π-conjugated polymer as an electron donor, and a fullerene derivative as an electron acceptor, is widely used in organic solar cells (OSCs) to facilitate efficient charge separation and extraction. However, the conventional BHJ system still suffers from unwanted phase segregation caused by the existence of significant differences in surface energy between the two BHJ components and the charge extraction layer during film formation. In the present work, we demonstrate a sophisticated control of fast film-growth kinetics that can be used to achieve a uniform distribution of donor and acceptor materials in the BHJ layer of OSCs without undesirable phase separation. Our approach involves depositing the BHJ solution onto a spinning substrate, thus inducing rapid evaporation of the solvent during BHJ film formation. The fast-growth process prevents the fullerene derivative from migrating toward the charge extraction layer, thereby enabling a homogeneous distribution of the fullerene derivative within the BHJ film. The OSCs based on the fast-growth BHJ thin film are found to exhibit substantial increases in JSC, fill factor, and a PCE up to 11.27 mA/cm2, 66%, and 4.68%, respectively; this last value represents a remarkable 17% increase in PCE compared to that of conventional OSCs.

L‐Arginine‐Doped PFN‐Br as a Cathode Interlayer for Conventional Organic Solar Cells

The cathode interlayer (CIL) plays a crucial role in organic solar cells (OSCs), which can establish an Ohmic contact between the active layer and the electrode, lower the electron extraction barriers, and minimize the charge carrier recombination. The CIL modification is a useful strategy for improving the performance of OSCs. Herein, an inexpensive water–alcohol‐soluble material known as L‐Arginine (L‐Arg) is introduced as a modifier for the PFN‐Br CIL, leading to successful optimization of the CIL quality. Following L‐Arg modification, the work function of the CIL is lowered and the electron extraction is facilitated. L‐Arg assists in exciton dissociation while suppressing both bimolecular and trap‐assisted recombination processes. The modified CIL establishes superior contact with the metal electrode due to its enhanced hydrophilicity, which helps electron collection. Consequently, the average power conversion efficiency increases from 10.54% in the reference device to 11.17% in the optimally doped device.

Bulk‐Heterojunction Electrocatalysts in Confined Geometry Boosting Stable, Acid/Alkaline‐Universal Water Electrolysis

AbstractAlkaline water splitting electrocatalysts have been studied for decades; however, many difficulties remain for commercialization, such as sluggish hydrogen evolution reaction (HER) kinetics and poor catalytic stability. Herein, by mimicking the bulk‐heterojunction morphology of conventional organic solar cells, a uniform 10 nm scale nanocube is reported that consists of subnanometer‐scale heterointerfaces between transition metal phosphides and oxides, which serves as an alkaline water splitting electrocatalyst; showing great performance and stability toward HER and oxygen evolution reaction (OER). Interestingly, the nanocube electrocatalyst reveals acid/alkaline independency from the synergistic effect of electrochemical HER (cobalt phosphide) and thermochemical water dissociation (cobalt oxide). From the spray coating process, nanocube electrocatalyst spreads uniformly on large scale (≈6.6 × 5.6 cm2) and is applied to alkaline water electrolyzers, stably delivering 600 mA cm−2 current for >100 h. The photovoltaic‐electrochemical (PV‐EC) system, including silicon PV cells, achieves 11.5% solar‐to‐hydrogen (STH) efficiency stably for >100 h.

Computational design of new polymers having low exciton binding energy for organic solar cells fabrication: Chemical generation and visualization

Conventional organic solar cell (OSC) fabrication, based on the hit and trial methodology, is quite laborious and lethargic, requiring extensive human workforce and instrumental resources. Recent advancements in machine learning (ML) approaches have revolutionized selection of the suitable active polymeric layer for OSC devices. Among numerous aspects impacting efficacy of the OSC fabrication, the lower exciton binding energy (Eb) was found one of the most crucial factors. The dataset containing Eb values was prepared from already documented literature on polymeric active layers of OSC devices. Various ML models were applied and tested to predict Eb values accurately, however, the random forest regressor model was proved to be the most efficient one. The ML analysis was further utilized to develop a new and novel chemical database that could be utilized as an active layer for the fabrication of OSCs. The synthetic accessibility (SA) score was also investigated to explore the relative ease by which a proposed polymeric material could be synthesized in practical lab. Interestingly, analysis of the top thirty generated polymeric materials exhibited extremely decent SA score, and remarkably lower Eb values; both properties are highly desirable for the fabrication of efficient OSCs. Further, we also applied deep learning approach to generate and screen new monomers with lower Eb and SA score. This effort reveals significance of the computational data-driven approaches for real-life applications. Our current contribution of the novel polymeric materials database having extremely low Eb values could be valuable for the fabrication of efficient OSC devices.

Perovskite Photovoltaics: Navigating Stability Challenges for Enhanced Efficiency

In the field of photovoltaics (PVs), perovskite‐based solar cells (PSCs) have become a game‐changing technology, boasting impressive improvements in cell efficiency and providing a promising substitute for conventional silicon, inorganic, and organic solar cells. Herein, the in‐depth analysis over the numerous stability problems that PSCs face, including both extrinsic problems like moisture, UV light, and temperature stability and intrinsic problems like hysteresis effects and metal–perovskite reactions, is examined. This article illuminates the cutting‐edge techniques used to improve PSC stability, thereby paving the way for their commercial viability. This review makes a significant contribution to the ongoing search for higher PV performance by offering a thorough analysis of the developments, challenges, and potential of perovskite‐based solar cells. It investigates printing methods, stability issues, uses, and the special qualities of perovskite materials, ultimately advancing comprehension and the creation of high‐efficiency PSCs.

Effect of solvent and thermal annealing on D18/Y6 polymer solar cells

Organic solar cells (OSCs) as emerging generation solar cells are required to face climate and energy challenges. In this regard, OSCs based on the D18:Y6 active layer with a ratio of 1:1.6 with thermal and solvent annealing as a post-treatment were fabricated. The effect of different thermal annealing with chloroform on the active layer and the cell performance was studied. Optical, morphological and thermal analysis are executed to investigate the effect of thermal with solvent annealing on the D18:Y6 active layer. Photoluminescence (PL), transmission electron microscope (TEM) and atomic force microscope (AFM) reveal that D18:Y6 film treated at 55 °C with chloroform for 5.0 min had the lowest PL intensity, interpenetrating grain networking structures and more smoother surface leads to optimize photo-induced charge transfer and exciton dissociation in the active layer. D18: Y6 blend film annealed at 80 °C with chloroform for 5.0 min exhibits higher roughness of 17.81 nm than 11.60 nm for D18:Y6 blend film treated at 55 °C. As a result, the optimal performance of the fabricated conventional OSCs based on active layer treated at 55 °C with chloroform had short-current density (Jsc), open circuit voltage (Voc), fill factor (FF) and efficiency of 60 mA/cm2, 0.70V, 39.8% and 16.5%, respectively. This study indicates additional thermal annealing with chloroform as a post-treatment enhances the device performance of OSCs.Graphical abstractStudying the effect of solvent vapor annealing with thermal annealing of D18:Y6 layer aspost-treatment on the performance of organic solar cells.

Stealthy Hyperuniform Surface Structures for Efficiency Enhancement of Organic Solar Cells

Low absorption in the thin active layer of conventional organic solar cells limits their power conversion efficiency. Structured surface layers are a common approach to diffracting incoming light, thus elongating its path through the active layer, thereby increasing the probability of absorption and hence the power conversion efficiency. While standard periodic structures diffract light into discrete angles, making them optimal only for specific wavelengths, random structures induce broadband, but nontailorable diffraction. Thus, instead, a stealthy hyperuniform structure, designed to exhibit beneficial diffraction properties is implemented: it directs the light into a predefined range of higher angles, prevents diffraction into small angles, and is thus ideal for a strong active path length enhancement. After numerical optimization of the feature height and diameter, the stealthy hyperuniform structure is fabricated in silicon by electron beam lithography and subsequently transferred into a transparent polymer via replica molding. Experimental diffraction images reveal a circular symmetric spectrum, inducing diffraction independent of the azimuthal angle and polarization of the incident light. The application of the stealthy hyperuniform structure on a poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione)]:3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d’]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene organic solar cell leads to a sharp increase in current density and power conversion efficiency.

Reexamining the Role of Solution-Cast Ferroelectric Polymer Interlayer toward Enhanced Efficiency and Stability in Conventional Organic Solar Cells.

Interfacial modification is crucial for achieving efficient and stable organic solar cells (OSCs). Herein, an N,N-dimethylformamide (DMF) solution-cast poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) interlayer was applied to enhance the efficiency and stability of a range of OSCs, and the underlying mechanism was revealed via morphological and device physics studies. DMF rinse during the P(VDF-TrFE) interlayer casting process strengthens π-π stacking of the active layer with fibril aggregation, optimized phase separation, and vertical component distribution, while the P(VDF-TrFE) interlayer with rich diploes contributes to increased surface potential and internal electric field. The synergistic effect of the P(VDF-TrFE) interlayer and DMF rinse increases the PCEs of PM6:IT-4F, PM6:C5-16, and PM6:L8-BO OSCs from 12.7, 17.9, and 18.2% to 13.1, 18.7, and 18.8%, respectively. Additionally, OSCs containing the P(VDF-TrFE) interlayer also showed improved storage stability.

Evaluation of the impact of trivalent metal doping on the performance of titanium dioxide as an electron transport layer of Inverted-Structured organic solar cells

Inverted organic solar cells (OSCs) are becoming more popular because to their better durability and photo stability; nonetheless, their power conversion efficiency (PCE) is lower than that of conventional OSCs due to the poor conductivity of the electron transport layer (ETL). Several doped metal oxides have been investigated as possible ETLs to overcome this problem. Various metal doped titanium dioxide (TiO2) has recently been tested as an ETL for photo- and air- stable OSCs. Due to their physicochemical features, trivalent metals are one of the best possibilities as a TiO2 doping reagent. Therefore, we investigate at how TiO2′s performance as an ETL of an inverted OSC may be affected by doping it with a very little quantity of trivalent metal in this study. Additionally, two other metals, such as Indium (In) and Gallium (Ga), are taken into consideration to test the impact of the doping metal's atomic size on TiO2′s performance as an ETL. The doped-TiO2 based OSC shows 10.24% higher PCE than undoped-TiO2 based OSC. Furthermore, despite the fact that Ga's atomic size is substantially smaller than Ti's and In's, both Ga doped-TiO2 based OSC (7.54%) and In-doped-TiO2 (7.47%) display almost identical PCE values.

Simple Solvent Treatment Enabled Improved PEDOT:PSS Performance toward Highly Efficient Binary Organic Solar Cells.

PSS is the most popular hole-transporting material (HTM) for conventional structural organic solar cell (OSC) devices, whose performance is of great importance for realizing high power conversion efficiency (PCE). However, its performance in OSC devices has been continuously challenged by various replacing materials and different doping strategies, for better conductivity, work function, and surface property. Here, we report a simple dopant-free method to tune the phase separation of the PEDOT:PSS layer, which results in better charge transport and extraction in devices. Specifically, high PCEs for binary polymer-small-molecule (>18%) and polymer-polymer (>17%) systems are simultaneously achieved. This work engineeringly provides encouraging improvement for OSC device performance with easy modification and scientifically offers insights into tuning the property of the PEDOT:PSS layer.

Efficient Cathode Buffer Material Based on Dibenzothiophene-S,S-dioxide for Both Conventional and Inverted Organic Solar Cells.

A novel conjugated molecule (PBSON) based on a main chain composed of bis(dibenzothiophene-S,S-dioxide) fused cyclopentadiene and side chains containing amino groups is presented as an efficient cathode buffer material (CBM) for organic solar cells (OSCs). PBSON showed a deep highest occupied molecular orbital (HOMO) energy level of -6.01 eV, which was beneficial for building hole-blocking layers at the cathodes of OSCs. The energy bandgap of PBSON reached 3.17 eV, implying high transmittance to visible and near-infrared light, which meant PBSON should be suitable for the applications to most inverted OSCs. The scanning Kelvin probe microscopy measurement and theoretical calculation on the PBSON/cathode interfacial interaction proved the excellent work function-regulating abilities of PBSON for various cathodes, suggesting that PBSON could promote the formation of Ohmic contacts at the cathodes and thus improve the transport and collection of electron carriers for OSCs. The characterization of electron-only devices demonstrated the good electron-transporting performance of PBSON at the cathodes. In the conventional OSCs, it was hinted that PBSON might restrain the infiltrations of evaporated cathode atoms into the active films, consequently reducing the reverse leakage currents. As a result, PBSON was able to boost the power conversion efficiencies (PCEs) by 58.2 and 56.4% for both conventional and inverted OSCs of the typical PTB7:PC71BM system, respectively, as compared to the unadorned devices. In terms of the classical PTB7-Th:PC71BM system, substantial increases in PCEs could also be found with PBSON interlayers, which were 54.7 and 59.8% for the conventional device and inverted device, respectively. Therefore, PBSON is a kind of promising CBM for realizing both conventional and inverted OSCs of high performance.

Annealing-Insensitive, Alcohol-Processed MoOx Hole Transport Layer for Universally Enabling High-Performance Conventional and Inverted Organic Solar Cells.

At present, most solution-processed molybdenum oxide (s-MoOx) hole transport layers (HTLs) are still mainly used in conventional organic solar cells (OSCs) but unsuitable for inverted OSCs. Herein, we demonstrate for the first time an annealing-insensitive, alcohol-processed MoOx HTL that can universally enable high-performance conventional and inverted OSCs. The s-MoOx HTL is spin-coated from the MoOx nanoparticle dispersion in alcohol, where the MoOx nanoparticles are synthesized by simple nonaqueous pyrolysis conversion of MoO2(acac)2. The MoOx nanoparticles possess uniform and very small sizes of less than 5 nm and can be well dispersed in alcohol, so the s-MoOx HTLs on ITO and active layer both show an overall uniform and smooth surface, suitable for conventional and inverted OSCs. In addition, the s-MoOx HTL possesses decent optical transmittance and appropriate work function. Utilizing the s-MoOx HTL annealed between room temperature and 110 °C and PM6:Y6 active layer, the conventional OSCs show an excellent power conversion efficiency (PCE) of 16.64-17.09% and the inverted OSCs also show an excellent PCE of 15.74-16.28%, which indicate that the s-MoOx HTL could be annealing-insensitive and universal for conventional and inverted OSCs. Moreover, conventional and inverted OSCs with the s-MoOx HTLs annealed at 80 °C both exhibit optimal PCEs of 17.09 and 16.28%, respectively, which are separately superior than that of the PEDOT:PSS-based conventional OSCs (16.94%) and the thermally evaporated MoO3 (e-MoO3)-based inverted OSCs (16.03%). Under light soaking and storage aging in air, the unencapsulated inverted OSCs based on the s-MoOx HTL show similarly excellent ambient stability compared to the e-MoOx-based devices. In addition, the s-MoOx HTL also shows a universal function in conventional and inverted OSCs with PBDB-T:ITIC and PM6:L8-BO active layers. Notably, the s-MoOx-based conventional and inverted OSCs with the PM6:L8-BO active layer exhibit very excellent PCEs of 18.21 and 17.12%, respectively, which are slightly higher than those of the corresponding PEDOT:PSS-based device (18.17%) and e-MoO3-based device (17.00%). The annealing-insensitive, alcohol-processed MoOx HTL may be very promising for flexible and large-scale processing conventional/inverted OSCs.

Recent Progress in Hole‐Transporting Layers of Conventional Organic Solar Cells with p–i–n Structure

AbstractRecently, organic solar cells (OSCs) have received rapid boosts in the power conversion efficiency (PCE), due to progresses in materials and device engineering. Several groups have reported champion PCEs over 19% in single‐junction, ternary, and tandem OSCs. In addition to the concentrated focus on the new design of OSC active materials, buffer layer materials, used for the interface layer providing the functionalities of interface charge transport and collection in OSCs, are of critical importance for the optimization of PCE. Compared with the electron transport layers (ETL), the hole transport layers (HTLs) have received less attention and are still dominated by the commercial material poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), which has limitations for the efficiency and OSC device stability enhancement. In this Review, the recent progress in HTL materials, including the modifications for PEDOT:PSS, alternative HTL materials based on polymers and inorganic oxide materials, etc, is summarized. This review also provides a summative prospect aiming to help scientists apprehend the current possibilities and challenges in this field.

Nucleobase Polymers Promote Low Work Function Surfaces in Organic Electronics

AbstractLow work function surfaces are crucial to electron extraction and injection in organic electronic devices. One of the challenges is developing general surface modifiers compatible with various organic semiconductors and device structures. Two novel nucleobase polymers are synthesized by reversible addition–fragmentation chain transfer polymerization. The nucleobase polymers show strong molecular dipole moments and superior film‐forming property as surface modifiers, which universally reduce work functions of common conductive electrodes. The integration of these nucleobase polymers into conventional or inverted organic solar cells (OSCs) boosts efficiencies of the devices to 17.25%, which is the highest in OSCs containing biomass‐derived interlayer materials. These nucleobase polymers are efficient and stable surface modifiers to remove energy barriers of diodes and transistors, improving electron transport between metal electrodes and organic semiconductors, which provide a new material platform for introducing biomass‐derivatives to produce low work function surfaces for high‐performance organic electronics.

Engineered Cathode Buffer Layers for Highly Efficient Organic Solar Cells: A Review

AbstractThis article presents an in‐depth insight into the most efficient cathode buffer layers (CBLs) in conventional and inverted organic solar cells (OSCs). The CBL can play a critical role in improving the short circuit current density (Jsc) and fill factor (FF) of the devices by minimizing the contact resistance and reducing charge recombination at electrode/photoactive layer interface, resulting in the efficient extraction of charge carriers and therefore improving the power conversion efficiency (PCE). This review explores CBL with respect to its effect on the physics of a device and electronic processes at the interface of CBL/photoactive layer and its impact on the overall performance of OSCs. Besides this, the role of CBL, its chemical composition, morphology, thickness, dopants, deposition conditions, etc., and their corresponding effects on the device performance of both conventional and inverted OSCs are discussed in detail. Finally, CBLs that provide the best performance are summarized and their chemical structures are discussed. This article will benefit the researchers working in the domain of OSCs by providing an understanding of the CBL layers, along with various interfacial processes.

Tin Oxide Electron Transport Layers for Air-/Solution-Processed Conventional Organic Solar Cells

Commercialization of organic solar cells (OSC) is imminent. Interlayers between the photoactive film and the electrodes are critical for high device efficiency and stability. Here, the applicability of SnO2 nanoparticles (SnO2 NPs) as the electron transport layer (ETL) in conventional OSCs is evaluated. A commercial SnO2 NPs solution in butanol is mixed with ethanol (EtOH) as a processing co-solvent to improve film formation for spin and slot-die coating deposition procedures. When processed with 200% v/v EtOH, the SnO2 NPs film presents uniform film quality and low photoactive layer degradation. The optimized SnO2 NPs ink is coated, in air, on top of two polymer:fullerene-based systems and a nonfullerene system, to form an efficient ETL film. In every case, addition of SnO2 NPs film significantly enhances photovoltaic performance, from 3.4 and 3.7% without the ETL to 6.0 and 5.7% when coated on top of PBDB-T:PC61BM and PPDT2FBT:PC61BM, respectively, and from 3.7 to 7.1% when applied on top of the PTQ10:IDIC system. Flexible, all slot-die-coated devices, in air, are also fabricated and tested, demonstrating the versatility of the SnO2 NPs ink for efficient ETL formation on top of organic photoactive layers, processed under ambient condition, ideal for practical large-scale production of OSCs.

Investigation of conventional and inverted organic solar cell from optical aspect

As an interesting research topic, investigation on organic solar cells is increasing day by day. In this study, the performance of conventional P3HT: PCBM based organic solar cell (OSC) structure and inverted organic solar cell (IOSC) structure has been investigated through optical simulation using GPVDM software. As an active layer material, P3HT: PCBM is used. Al, ITO, PEDOT: PSS and TiO2 is used as cathode, anode, hole transporting layer (HTL) and electron transporting layer (ETL) respectively for OSC structure. In case of IOSC, Ag has been used as an anode. Investigations have been made to study the effect of active layer thickness on the exciton generation rate. It has been found that the exciton generation rate is oscillatory due to optical interference effect for both OSC and IOSC structure. Photon absorption reduces due to increase in active layer thickness. However, exciton generation increases due to creation of more peak into the active layer.

A pH‐Neutral Polyelectrolyte Hole Transport Layer for Improved Energy Band Structure at the Anode/PTB7 Junction and Improved Solar Cell Performance

In organic solar cells (OSCs), interfacial properties between the donor phase and hole transport layers (HTLs) are critical factors which govern charge extraction efficiency. Many ionic and polar materials are known to function as effective interfacial layers; however, an understanding of how ionic moieties affect the electronic band structure and characteristics of OSCs is lacking. Herein, a new, pH‐neutral polyelectrolyte is introduced that resolves several problems which are encountered with the commonly used HTL, poly(3,4‐ethylenedioxythiopene):polystyrenesulfonate (PEDOT:PSS). An effective p‐type polyelectrolyte dopant is designed, comprising an anionically charged PSS backbone with easily reduced Cu2+ counterions (Cu:PSS), and interfacial properties for HTL/donor interfaces by photoelectron spectroscopy are analyzed. The effects of the polyelectrolyte on interfacial energy levels and charge extraction efficiency between the active layer and HTL are quantified. Using optimized processing conditions, the efficiency can be improved from 8.31% to 9.28% in conventional OSCs compared with a standard PEDOT:PSS HTL. The energy‐level alignment at the HTLs/donor interface determined by UV photoelectron spectroscopy measurements reveals the origin of distinct differences in device performances. The reduced ionization potential (IP) and hole injections barrier (Φh) at the HTL/donor interface play a crucial role in efficient charge extraction in conventional OSCs.