Efficient Organic Solar Cells Research Articles

Improving efficiency and flexibility of non-halogenated solvent-processed dual-layer organic solar cells through solvent vapor annealing

Dual-layer organic solar cells (OSCs), fabricated through sequential-casting with separately dissolved donor and acceptor materials, offer simplified solution preparation and morphology control. However, the poor solubility of organic materials in non-halogenated solvents often results in undesirable vertical component distribution and insufficient donor/acceptor interfaces in non-halogenated solvent-processed dual-layer OSCs, adversely affecting photovoltaic performance and flexibility. In this study, we applied a solvent vapor annealing (SVA) method using CS2 solvent in o-xylene solvent-processed dual-layer OSCs. The SVA method effectively adjusted the vertical component distribution of the active layer and increased the donor/acceptor interfaces, leading to an improved power conversion efficiency (PCE) of 17.24 %. Additionally, SVA films exhibited superior tensile properties, with a crack onset strain of 5.07 %, surpassing that of the as-cast films (4.32 %), attributed to the stronger interaction between the donor and acceptor layers with more donor/acceptor interfaces. Consequently, large-area (1 cm2) flexible devices achieved a significant efficiency of 14.20 % and maintained excellent mechanical flexibility, with 80 % of the initial efficiency retained after 1000 bending cycles. This work presents an effective approach for fabricating high-performance non-halogenated solvent-processed flexible dual-layer OSCs.

Exploration of promising photovoltaic properties of bisisoindigo-based heterocyclic chromophores for organic solar cells: A DFT/TD-DFT study

In the current study, a series of A1–π–A2–π–A1 type bisisoindigo-based organic compounds (BTIND1–BTIND9) were designed via the structural tailoring of the reference compound (BTINR) at terminal acceptors for the organic solar cells (OSCs). Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) approaches were utilized to estimate the influence of end-capped engineering over their photovoltaic properties of BTIND1–BTIND9. After their structural optimization, various analyses like, open circuit voltage (Voc), absorption spectra (λmax), frontier molecular orbitals (FMOs), density of states (DOS), binding energy (Eb) and transition density matrix (TDM) were performed at the B3LYP/6-311G(d,p) level. The band gaps range of the engineered molecules was observed as 1.776–1.649 eV, lesser than the BTINR reference (1.812 eV). Their TDM and DOS details further revealed electronic charge transfer in the designed derivatives. The higher λmax values were found in the visible and near-infrared regions i.e., 666.904–701.149 nm in the chloroform solvent and 661.778–895.581 nm in the gaseous phase. Furthermore, their open-circuit voltage (Voc) was determined with PTB7 donor polymer and showed significant values. Among all, BTIND5, BTIND7 and BTIND8 compounds were investigated with remarkable photovoltaic properties. These chromophores possessed least energy gaps (1.649, 1.668 and 1.664 eV) and bathochromic shifts (698.070, 699.646 and 701.149 nm) with least binding energies and prominent Voc results. The above-mentioned outcomes demonstrate that the end-capped modification of bisisoindigo-based molecule is an effective strategy to obtain highly efficient OSCs.

Molecular Design and Organic Photovoltaic Applications of Carboxylate‐Functionalized P‐type Polymers

AbstractThe significant progress of p‐type and n‐type active layer materials in the past several years has pushed the power conversion efficiency (PCE) of organic solar cells (OSCs) toward 19%. Due to the relatively low synthesis cost and simple synthesis method of carboxylate‐containing building blocks, including thiophene, thieno[3,2‐b]thiophene, thieno[3,4‐b]thiophene, furan, pyrazine, benzodithiophene, benzothiazole, quinoxaline, etc., are widely used to construct p‐type photovoltaic polymers. These resulting carboxylate‐bearing polymers present downward energy levels, high absorption coefficient, narrow bandgap, high hole mobility, and strong aggregation behavior, which have dabbled in the fabrication of mechanically stretchable, semitransparent, indoor, and tandem OSCs, etc., and produce excellent photovoltaic performance. The low‐cost carboxylate‐containing copolymers exhibit a satisfying PCE approaching 17%, and the random terpolymer systems achieve a high PCE over 19%. This review focuses on the progress of carboxylate‐containing photovoltaic polymers, summarizes the molecular characteristics, discusses their structure‐performance relationship, and offers a summary and outlook on the challenges for future molecular development.

Increasing terminal alkyl chain length for a better small molecule organic solar cell donor

Optimizing the alkyl chains within a terminal group is considered to be a highly effective approach for boosting the power conversion efficiency (PCE) of all small-molecule organic solar cells (ASM-OSCs). In this study, we focus on designing and synthesizing small molecular (SM) donor compounds with different end-group alkyl chain lengths to study their impact on OSC performance. Under optimized conditions, OSC devices based on BTR-Cl-C8:Y6 demonstrate higher PCE of 14.43 % compared to those based on BTR-Cl:Y6. Moreover, BTR-Cl-C8 exhibits reduced levels of bimolecular recombination and trap-assisted recombination, enhanced capability for exciton dissociation and charge collection, and extended carrier lifetimes. These results highlight the significance of molecular design strategies in optimizing OSC performance and offer valuable insights for the development of efficient and stable ASM-OSCs.

“Mutually Doped” Conjugated Polyelectrolyte‐Polyoxometalate Complex as Hole Transporting Material for Efficient Organic Solar Cells

Comprehensive SummaryCompared to electron transporting layer materials, the species and numbers of hole transporting layer (HTL) materials for organic solar cells (OSCs) are rare. The development of HTL materials with excellent hole collection ability and non‐corrosive nature is a long‐standing issue in the field of OSCs. Herein, we designed and synthesized a series of conjugated polyelectrolytes (CPEs) with continuously varied energy levels toward HTL materials for efficient OSCs. Through a “mutual doping” treatment, we obtained a CPE composite PCT‐F:POM with a WF of 5.48 eV and a conductivity of 1.56 х 10–3 S/m, meaning that a good hole collection ability can be expected for PCT‐F:POM. The OSC modified by PCT‐F:POM showed a high PCE of 18.0%, which was superior to the reference device with PEDOT:PSS. Moreover, the PCT‐F:POM‐based OSC could maintain 91% of the initial PCE value after storage of 20 d, meaning that the long‐term stability of OSCs is improved by incorporating the PCT‐F:POM HTL. In addition, PCT‐F:POM possesses good compatibility with large‐area processing technique; i.e., a PCT‐F:POM HTL was processed by the blade‐coating method for fabricating 1 cm2 OSC, and a PCE of 15.1% could be achieved. The results suggest the promising perspective of PCT‐F:POM in practical applications.

Advancements in P3HT:PCBM solar cells through experimental and simulated techniques

Organic solar cells are a promising alternative in photovoltaics due to their low manufacturing cost and flexibility. In this study, we developed an organic solar cell of structure (ITO/PEDOT:PSS/P3HT:PCBM/Al) where the active layer is represented by P3HT:PCBM. Experimental studies revealed that this layer has an energy gap of 1.9 eV and a good absorption coefficient of 3×105cm−1 . Using analytical and experimental methods based on (J–V–T) curves, we extracted the key parameters of our device, including parasitic resistances ( Rs and Rsh ), ideality factor (n), and Schottky potential barrier ( ϕB) at different temperatures. Also the charge transport mechanism in our junction is identified in this study. We then used simulation to evaluate the performance of our solar cell, obtaining an initial efficiency of 2.13%, in line with experimental results from other research. Our results confirm the feasibility of our theoretical approach, with performance consistent with previous work. However, by introducing an electron transport layer layer (PFN-Br or PDINO), we were able to improve efficiency up to 4.25%. These results highlight the importance of optimising intermediate layers to maximise the efficiency of organic solar cells.

DFT and TD-DFT Investigations for the Limitations of Lengthening the Polyene Bridge between N,N-dimethylanilino Donor and Dicyanovinyl Acceptor Molecules as a D-π-A Dye-Sensitized Solar Cell.

One useful technique for increasing the efficiency of organic dye-sensitized solar cells (DSSCs) is to extend the π-conjugated bridges between the donor (D) and the acceptor (A) units. The present study used the DFT and TD-DFT techniques to investigate the effect of lengthening the polyene bridge between the donor N, N-dimethyl-anilino and the acceptor dicyanovinyl. The results of the calculated key properties were not all in line with expectations. Planar structure was associated with increasing the π-conjugation linker, implying efficient electron transfer from the donor to the acceptor. A smaller energy gap, greater oscillator strength values, and red-shifted electronic absorption were also observed when the number of polyene units was increased. However, some results indicated that the potential of the stated dyes to operate as effective dye-sensitized solar cells is limited when the polyene bridge is extended. Increasing the polyene units causes the HOMO level to rise until it exceeds the redox potential of the electrolyte, which delays regeneration and impedes the electron transport cycle from being completed. As the number of conjugated units increases, the terminal lobes of HOMO and LUMO continue to shrink, which affects the ease of intramolecular charge transfer within the dyes. Smaller polyene chain lengths yielded the most favorable results when evaluating the efficiency of electron injection and regeneration. This means that the charge transfer mechanism between the conduction band of the semiconductor and the electrolyte is not improved by extending the polyene bridge. The open circuit voltage (VOC) was reduced from 1.23 to 0.70 V. Similarly, the excited-state duration (τ) decreased from 1.71 to 1.23 ns as the number of polyene units increased from n = 1 to n = 10. These findings are incompatible with the power conversion efficiency requirements of DSSCs. Therefore, the elongation of the polyene bridge in such D-π-A configurations rules out its application in solar cell devices.

Trialkylsilyl-thiophene-conjugated acceptor for efficient organic solar cells compatible with spin-coating and blade-coating technologies

Trialkylsilyl-thiophene-conjugated acceptor for efficient organic solar cells compatible with spin-coating and blade-coating technologies

Binary Organic Solar Cells with Exceeding 19% Efficiency via the Synergy of Polyfluoride Polymer and Fluorous Solvent.

Rational molecular design and suitable device engineering are two important strategies to boost the efficiencies in organic solar cells (OSCs). Yet these two approaches are independently developed, while their synergy is believed to be more productive. Herein, a branched polyfluoride moiety, heptafluoroisopropoxyl group, is introduced into the side chains of conjugated polymers for the first time. Compared with the conventional alkyl chain, this polyfluoride chain can endow the resulting polymer namely PF7 with highly packing order and strong crystallinity owing to the strong polarization and fluorine-induced interactions, while good solubility and moderate miscibility are retained. As a result, PF7 comprehensively outperforms the state-of-the-art polymer PM6 in photovoltaic properties. More importantly, based on the solubility of heptafluoroisopropoxyl groups in fluorous solvents, a new post-treatment denoted as fluorous solvent vapor annealing (FSVA) is proposed to match PF7. Differing from the existing post-treatments, FSVA can selectively reorganize fluoropolymer molecules but less impact small molecules in blend films. By employing the synergy of fluoropolymer and fluorous solvent, the device achieves a remarkable efficiency of 19.09%, which is among the best efficiencies in binary OSCs. The polymer PF7 and the FSVA treatment exhibit excellent universality in various OSCs with different material combinations or device architectures.

19.36% Efficiency Organic Solar Cells Based on Low‐Cost Terpolymer Donors with Simple Molecular Structures

AbstractLow cost and high performance are key elements for the industrialization of organic solar cells (OSCs). In view of this, developing highly‐efficient organic photovoltaic molecules with simple chemical structure is one of the most effective countermeasures. Herein, three simple‐structure terpolymers PTQ12‐5, PTQ12‐10, and PTQ12‐15 are designed and synthesized, by embedding difluoro‐substituted bithiophene (2T‐2F) unit into the backbone of low‐cost and high‐efficiency polymer PTQ10. The synthesis of three terpolymers contains only two‐step synthetic routes and over 85% synthetic yields from cheap raw compounds, thus exhibiting distinctly low‐cost characteristic. Remarkably, PTQ12‐5 shows significantly higher absorbance coefficient and hole mobility than PTQ10. Consequently, PTQ12‐5‐based OSCs shows more efficient exciton dissociation and charge transfer, suppressed carrier recombination, tighter molecular π‐π stacking, and faster and more balanced charge transport, thus demonstrates a significantly improved efficiency of 18.77% than that of PTQ10‐based device (18.03%). Moreover, an outstanding efficiency of 19.36% is achieved in PTQ12‐5‐based ternary device by further modulating the energy level alignment and blending features of photoactive molecules, which is the highest efficiency of OSCs based on low‐cost polymers to date. This work has significant implications for guiding the design of low‐cost and high‐performance organic photovoltaic materials.

All chlorination strategy on end-group of guest acceptor enables 18.39 % efficiency and high VOC for ternary organic solar cells

The ternary strategy has been proven to be an effective method to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). In this work, a new non-fullerene fused-ring acceptor (BTMe-8Cl) with 3,8-dimethylbenzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTMe) core and all chlorination end-group (4,5,6,7-tetrachloro-1H-indene-1,3(2H)-dione) is synthesized and incorporated as a guest electron acceptor in PM6:Y6:BTMe-8Cl ternary system. The addition of BTMe-8Cl effectively improves the open-circuit voltage (VOC) of the ternary OSCs due to the higher lowestunoccupied molecular orbital (LUMO) energy level of BTMe-8Cl than that of Y6. Fine-tuning the proportion of BTMe-8Cl in ternary OSCs results in the optimal phase separations in the ternary films. Finally, an excellent PCE of 18.39 % and a VOC of 0.896 V are achieved for the ternary OSCs based on PM6:Y6:BTMe-8Cl (1:1.2:0.2). Especially, the VOC of 0.896 V is the highest value for PM6:Y6 system up to now.

5-Chlorobenzoxazole as solid additive for efficient organic solar cells

Adding solid additives to the active layer is a simple and efficient method to adjust the morphology of the active layer to obtain appropriate phase separation, thus improving the organic solar cell device performance. We found a 5-Chlorobenzoxazole molecule as a solid additive to PM6:Y6 system, which increased the filling factor from 66.2 % to 71.0 % and the PCE from 14.8 % to 16.1 %. The results indicate that 5-Chlorobenzoxazole can interact with Y6, thus optimizing the morphology of the active film, enhancing the ability of charge extraction, and further improving FF and PCE.

Improved performance of ternary organic solar cells based on both bulk and pseudo-planar heterojunction active layer

The high photovoltaic conversion efficiency (PCE) of ternary organic solar cells (OSCs) based on PTB7-Th, PC71BM and IEICO-4F material is obtained, the short-circuit current density (J SC), fill factor (FF), and open-circuit voltage is 25.90 mA cm−2, 73.20% and 0.71 V, respectively. PCE is as high as 13.53%. It is the highest PCE of ternary OSCs based on PTB7-Th, PC71BM and IEICO-4F materials for all we know. The narrow bandgap material of IEICO-4F is deposited on PTB7-Th:PC71BM bulk heterojunction (BHJ) by layer-by-layer process. We constructed the dual bandgap active layer both BHJ and pseudo-planar heterojunction (P-PHJ), it could be defined as ternary BHJ/P-PHJ of OSCs. This type of OSCs is not only the complementary bandgap material of the active layer, but also increasing the donor/acceptor (D/A) interface. The excitons generation and collection of the device are increased leading a higher J SC and FF. The semitransparent OSCs (ST-OSCs) is prepared by varying the thickness of Ag electrode and PCE can reach 9.70%, and the average visible light transmittance and light use efficiency of ST-OSCs are improved effectively.

Designing simple non-fused terthiophene-based electron acceptors for efficient organic solar cells

Low-cost photovoltaic materials are essential for realizing large-scale commercial applications of organic solar cells (OSCs). However, highly efficient OSCs based on low-cost photovoltaic materials are scarce due to a deficiency in understanding the structure-property relationship. Herein, we investigated two low-cost terthiophene-based electron acceptors, namely, 3TC8 and 3TEH, with 3,4-bis(octan-3-yloxy)thiophene, differing only in the alkylated thiophene-bridges. Both acceptors exhibit low optical gaps (∼1.43 eV) and possess deep highest occupied molecular orbital (HOMO) levels (∼−5.8 eV). Notably, the single-crystal structure of 3TEH demonstrates highly planar conjugated backbone and strong π-π stacking between intermolecular terminal groups, attributed to the presence of the bulky alkylated noncovalently conformational locks. Upon utilizing both acceptors to fabricate OSCs, the 3TC8-based device exhibited a power conversion efficiency (PCE) of 11.1%, while the 3TEH-based OSC demonstrated an excellent PCE of 14.4%. This PCE is the highest among OSCs based on terthiophene-containing electron acceptors. These results offer a new strategy for designing low-cost electron acceptors for highly efficient OSCs.

Acceptor molecules with Carbon–Carbon singly bonded central and terminal units for efficient P3HT-based organic solar cells

Herein, we synthesized two small molecules named as 4TBTCN and 6TBTCN with strongly electron-rich 4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydrothieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene or 6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydrothieno[2″,3′′:4′,5′]thieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2‴,3‴:4″,5′′]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene as central unit and weak electron-withdrawing benzo[c] [1,2,5] thiadiazole-4-carbonitrile as termini, which were connected by C–C single bond. Both molecules exhibited medium optical bandgap and high-lying frontier molecular orbital energy levels, which were matched with those of the representative low-cost polymer donor P3HT. Moreover, 4TBTCN and 6TBTCN showed high stability under continuous illumination and base condition, owing to a lack of exocyclic vinyl group between the central unit and end group. Compared to P3HT:6TBTCN, P3HT:4TBTCN blend system displayed lower miscibility and thus more distinct phase separation, leading to more efficient charge transport and collection. Although the LUMO energy level of 4TBTCN was 0.15 eV deeper than that of 6TBTCN, the energy loss for P3HT:4TBTCN based device was similar to that of P3HT:6TBTCN based device. As a result, P3HT:4TBTCN based device displayed a similar open-circuit voltage but higher fill factor and short-circuit current density, yielding a superior power conversion efficiency, in comparison to P3HT:6TBTCN based device. This work provides a new strategy for design of efficient and stable acceptor molecules.

Correlating Aggregation Ability of Polymer Donors with Film Formation Kinetics for Organic Solar Cells with Improved Efficiency and Processability.

Film formation kinetics significantly impact molecular processability and power conversion efficiency (PCE) of organic solar cells. Here, two ternary random copolymerization polymers are reported, D18─N-p and D18─N-m, to modulate the aggregation ability of D18 by introducing trifluoromethyl-substituted pyridine unit at para- and meta-positions, respectively. The introduction of pyridine unit significantly reduces material aggregation ability and adjusts the interactions with acceptor L8-BO, thereby leading to largely changed film formation kinetics with earlier phase separation and longer film formation times, which enlarge fiber sizes in blend films and improve carrier generation and transport. As a result, D18─N-p with moderate aggregation ability delivers a high PCE of 18.82% with L8-BO, which is further improved to 19.45% via interface engineering. Despite the slightly inferior small area device performances, D18─N-m shows improved solubility, which inspires to adjust the ratio of meta-trifluoromethyl pyridine carefully and obtain a polymer donor D18─N-m-10 with good solubility in nonhalogenated solvent o-xylene. High PCEs of 13.07% and 12.43% in 1 cm2 device and 43 cm2 module fabricated with slot-die coating method are achieved based on D18─N-m-10:L8-BO blends. This work emphasizes film formation kinetics optimization in device fabrication via aggregation ability modulation of polymer donors for efficient devices.

Mechanics manipulation in large-area organic solar modules achieving over 16.5 % efficiency

High-efficiency organic solar cells (OSCs) are typically produced through spin-coating, restricting their application to small areas. Blade-coating, however, emerging as a promising method for large-scale production, yet faces challenges in film morphology optimization, which often leads to reduced power conversion efficiency (PCE). This study delves into the influence of both liquid and solid additives on the morphology of active layer in blade-coated OSCs, comparing them with spin-coated counterparts, using the high-efficiency PM6:D18:BTP-eC9 active layer. For the first time, we discovered the distinct impacts of solid versus liquid additives on the film uniformity, phase separation and crystalline regulation in blade-coating technique. Our findings reveal that liquid additives in blade-coating trigger outward Marangoni flow, causing undesirable material aggregation and phase separation, thereby impairing device performances. Conversely, switching to solid additives, like 1,4-Diiodobenzene (DIB), prevents these detrimental changes in fluid mechanics and preserves the desired additive effects. We demonstrate that solid additives can significantly change these inferior behaviors introduced by liquid additives in blade-coating, regulate phase separation, enhance π-π accumulation and delay crystallization, and ultimately boost OSC efficiency. Using DIB solid additive, we achieved a PCE of 18.81 % in blade-coated devices. Scaling up by 252 times, the PCE of large-area OSC module (15.64 cm²) sustained at 16.70 % (certified 16.66 %), ranking among the highest efficiency for OSC modules reported so far. These modules also exhibited exceptional storage stability, retaining 98 % efficiency after 5880 h in a nitrogen atmosphere. This research also provides a comprehensive understanding from various film characterizations and the perspective of fluid mechanics normally lack in the research. This research not only establishes a new framework for high-performance and large-area OSC modules but also extends its findings to other OSC systems with different additives, demonstrating a roll-to-roll compatible technique.

Engineering of asymmetric A1-D1-A2-D2-A1 type non-fullerene acceptors of 4T2CSi–4F derivatives to enhance photovoltaic properties: A DFT study

Designing efficient, non-fused ring-based organic solar cells (OSCs) with high open circuit voltage is a significant challenge. The present research proposes seven novel moieties generated from an existing 4T2CSi–4F (R) asymmetric molecule to increase efficiency. The density functional theory (DFT) was used to examine several essential characteristics like optical, electronic, and efficiency-related properties of molecules. It is revealed that newly presented molecules have superior features that are required to manufacture efficient organic solar cells. They exhibit a lower band gap between 2.05 and 2.34 eV and have a planar shape. Six moieties exhibit lower excitation energy values in the gas and chloroform phases, and five moieties have more excellent dipole moments than the R molecule. UA1 and UA2 show remarkable enhancement in the optoelectronic properties, exhibiting the greater λmax at 773 nm and a smaller excitation energy of 1.60 eV. All the newly presented molecules have lower ionization potential and reorganization energies of the electron. The open circuit voltage (Voc) of five newly designed molecules is greater, varying from 1.40 to 1.55 eV, than R (Voc = 1.38 eV). Furthermore, the newly designed molecules, except UA1 and UA2, show more excellent fill factor (FF) than the R molecule. This significant increase in efficiency-associated metrics (FF and Voc) suggests that these molecules may be effectively implemented to manufacture an upgraded version of OSCs.

Dipole Moments Regulation of Biphosphonic Acid Molecules for Self-assembled Monolayers Boosts the Efficiency of Organic Solar Cells Exceeding 19.7.

PSS has been widely used as a hole extraction layer (HEL) in organic solar cells (OSCs). However, their acidic nature can potentially corrode the indium tin oxide (ITO) electrode over time, leading to adverse effects on the longevity of the OSCs. Herein, we have developed a class of biphosphonic acid molecules with tunable dipole moments for self-assembled monolayers (SAMs), namely, 3-BPIC(i), 3-BPIC, and 3-BPIC-F, which exhibit an increasing dipole moment in sequence. Compared to centrosymmetric 3-BPIC(i), the axisymmetric 3-BPIC and 3-BPIC-F exhibit higher adsorption energies (Eads) with ITO, shorter interface spacing, more uniform coverage on ITO surface, and better interfacial compatibility with the active layer. Thanks to the incorporation of fluorine atoms, 3-BPIC-F exhibits a deeper highest occupied molecular orbital (HOMO) energy level and a larger dipole moment compared to 3-BPIC, resulting in an enlarged work function (WF) for the ITO/3-BPIC-F substrate. These advantages of 3-BPIC-F could not only improve hole extraction within the device but also lower the interfacial impedance and reduce nonradiative recombination at the interface. As a result, the OSCs using SAM based on 3-BPIC-F obtained a record high efficiency of 19.71%, which is higher than that achieved from the cells based on 3-BPIC(i) (13.54%) and 3-BPIC (19.34%). Importantly, 3-BPIC-F-based OSCs exhibit significantly enhanced stability compared to that utilizing PEDOT:PSS as HEL. Our work offers guidance for the future design of functional molecules for SAMs to realize even higher performance in organic solar cells.

Improving the Optoelectrical Properties of a Nickel Oxide Hole Transport Layer by Hydrogen Peroxide Treatment for Efficient Organic Solar Cells

Improving the Optoelectrical Properties of a Nickel Oxide Hole Transport Layer by Hydrogen Peroxide Treatment for Efficient Organic Solar Cells