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Publication date: June 2021

Source: Nano Energy, Volume 84

Author(s): Dong Yang, Xiaorong Zhang, Yuchen Hou, Kai Wang, Tao Ye, Jungjin Yoon, Congcong Wu, Mohan Sanghadasa, Shengzhong (Frank) Liu, Shashank Priya

Publication date: June 2021

Source: Nano Energy, Volume 84

Author(s): Song Yi Park, Sreelakshmi Chandrabose, Michael B. Price, Hwa Sook Ryu, Tack Ho Lee, Yun Seop Shin, Ziang Wu, Woojin Lee, Kai Chen, Shuixing Dai, Jingshuai Zhu, Peiyao Xue, Xiaowei Zhan, Han Young Woo, Jin Young Kim, Justin M. Hodgkiss

Publication date: 17 March 2021

Source: Joule, Volume 5, Issue 3

Author(s): Qian Kang, Zhong Zheng, Yunfei Zu, Qing Liao, Pengqing Bi, Shaoqing Zhang, Yi Yang, Bowei Xu, Jianhui Hou

An organic–inorganic hybrid electrolyte with aligned energy levels, self‐doping behavior, and improved electron mobility and conductivity was developed. It facilitates electron transport and boosts the power conversion efficiency of organic solar cells to 17.19 %.

Abstract

An organic–inorganic hybrid electrolyte based on a cyclic Ti‐oxo cluster as the inorganic core and naphthalene‐based organic ammonium bromide salts as the electrolyte was developed with easy synthesis and low cost. The new hybrid electrolyte exhibits excellent solubility in methanol, aligned work function, good conductivity, and amorphous state in thin film, enabling its successful application as a cathode interlayer in organic solar cells with a high power conversion efficiency of 17.19 %. This work demonstrates that the hybrid electrolytes are a new kind of semiconductor, exhibiting promising applications in organic electronics.

Interfacial issues and/or low light reflection existing in current solution-processed top electrodes have limited the efficiency of fully-solution-processed organic solar cells to <12%. A nonimmersive sintering strategy is developed to sinter isolated silver nanoparticles to form a continuous Ag electrode in dry condition, which successfully addresses the interfacial issues and enables high light reflection, leading to a breaking efficiency of 15.0%.

Abstract

A solution-processed top electrode is critical to unlock the full potential of all-solution-processed organic solar cells (OSCs) for practical applications. However, the enabled devices suffer from low efficiency (<12%) mainly because of the irreversible damages induced by the top-electrode deposition process. Herein, a strategy of dry and nonimmersive sintering is demonstrated by introducing a hydrogen-intercalated molybdenum oxide layer to sinter isolated Ag nanoparticles into the top electrode (all from solution process) with little influences/issues on underlying device structures. Fundamentally, it is unveiled that the intercalated hydrogen will bond with the amino group of the ligands around Ag nanoparticles, which promotes the exposed nanoparticles to merge along a certain crystal orientation (≈45°) and form a conductive electrode (8.6 Ω sq⁻¹). Importantly, the sintered electrode offers 70% optical reflection in the 700–1050 nm wavelength region, which is essential to enhance the light absorption of high-performance nonfullerene acceptors. Consequently, a record efficiency of 15% is achieved, driving all-solution processed OSCs toward commercial applications.

A power conversion efficiency of 16.17% is achieved in the doctor‐bladed PM6:Y6‐2Cl device with CF:CB co‐solvent, which is much higher than those of CF‐ and CB‐processed devices. Of note is that the use of this co‐solvent approach in the other two high‐performance photovoltaic systems is also confirmed, demonstrating its good generality of employing in the printing organic solar cells.

Abstract

Studies of the relationship between blend microstructure and photovoltaic performance are becoming more common, which is a prerequisite for rationally improving device performance. Non‐fullerene acceptors usually have planar backbone conformation and strong intermolecular packing, normally resulting in excessive phase separation. Herein, an effective co‐solvent blending strategy to turn the molecular organization of a chlorinated small molecule acceptor Y6‐2Cl and phase separation of the corresponding active layer with PM6 as donor is demonstrated. The in situ photoluminescence measurements and relevant morphological characterizations illustrate that the film‐forming process is fine‐turned when using the mixtures of chloroform (CF) and chlorobenzene (CB) solvents, and the blend showed high domain purity with suitable phase‐separated networks. Thus, better exciton dissociation and charge generation, more balanced charge transport, and less recombination loss are obtained in the co‐solvent blade‐coated devices. As a result, a maximum power conversion efficiency (PCE) of 16.17% is achieved, which is much higher than those of CF‐ and CB‐bladed devices (14.08% and 11.44%, respectively). Of note is that the use of this co‐solvent approach in the other two high‐performance photovoltaic systems is also confirmed, demonstrating its good generality of employing in the printing organic solar cells.

The controllable formation of an ordered vacancy compound (OVC) is successfully achieved through a facile solution method. By using this process, the Cu(In,Ga)Se₂ (CIGS) thin film with OVC exhibits improved heterojunction quality and the interface deep defect density is dramatically decreased. Consequently, a champion device efficiency of 16.39% is obtained, which is the highest reported value among solution‐processed CIGS solar cells.

Abstract

Solution processing of Cu(In,Ga)Se₂ (CIGS) absorber makes it cost‐competitive in the photovoltaic market. It is reported that copper‐poor ordered vacancy compound (OVC) is crucial for high performance CIGS solar cells. However, in solution process method, controllable formation of OVC is unavailable and limited research has been carried out. In this work, the controllable formation of the OVC phase on the CIGS surface is successful by controlling the selenization temperature and intentional variation of Cu/(In+Ga) stoichiometry in precursors for top layers and bulk layers deposition. The effects of OVC contents on the device performance are investigated. The CIGS thin film with OVC phase exhibits a lower valence band position. Meanwhile, the CIGS devices with optimized OVC content show decreased interface defects density and better carrier collection ability. The above advantages translate into a champion PCE of 16.39% for CIGS device with OVC phase, which is the champion performance among non‐hydrazine solution‐processed CIGS solar cells. The results demonstrate that the controllable formation of OVC phase approach should make a significant contribution to the efficiency promoting of solution processed CIGS solar cells.

Nonstoichiometric copper selenide (Cu_{2– x} Se) nanoplates are prepared via a convenient solution‐based method. The reversible displacement reaction between magnesium ions and copper ions in Se²⁻ sub‐lattices can effectively avert the lattice collapse of Cu_{2– x} Se and reduce the energy barrier for lattice reconstruction, significantly improving the electrochemical performance of Cu_{2– x} Se cathode in rechargeable magnesium batteries.

Abstract

Rechargeable magnesium batteries (RMBs) based on metal Mg anodes have shown great potential owing to the abundant natural resources, high volumetric capacity, and low safety hazard. Nevertheless, the development of RMBs is hampered by the sluggish kinetics of Mg²⁺ diffusion and the limited cyclability of cathode materials. Herein, nonstoichiometric copper selenide (Cu_{2– x} Se) are synthesized via a solution‐based method and exploited as a durable cathode material based on ionic displacement mechanism for RMBs. The copper ions in the Se²⁻ based sub‐lattices are reversibly exchanged by Mg²⁺ ions without causing lattice collapse. Owing to the same face‐centered cubic Se²⁻ sub‐lattices and similar unit cell size of Cu_{2– x} Se and MgSe, the energy barrier for lattice reconstruction during cycling processes is very low, significantly improving the rate performance, structural stability, and cycle life of the Cu_{2– x} Se cathode. Moreover, metal Cu is in situ generated during discharging, thus greatly facilitating electron transport. Comprehensive characterizations confirm that the Cu_{2– x} Se cathode undergoes reversible copper ion extrusion/reinjection during the discharge−charge steps. This work suggests the great potential for exploring high‐performance electrode materials based on ionic displacement mechanism for advanced multivalent‐ion secondary batteries.

The stabilizing function of the alloy states is revealed based on simultaneous efficiency and storage stability boosting in PM6:BTP-4Cl:PDI-2T and PM6:DRCN5T:BTP-4Cl ternary devices. The improved stability can be rationalized by two mechanisms: (1) the acceptor alloys enhance the conformational rigidity of BTP-4Cl molecules. (2) The donor alloys optimize the fibril network of PM6 to restrict the aggregation of the BTP-4Cl acceptor.

Abstract

Despite considerable advances devoted to improving the operational stability of organic solar cells (OSCs), the metastable morphology degradation remains a challenging obstacle for their practical application. Herein, the stabilizing function of the alloy states in the photoactive layer from the perspective of controlling the aggregation characteristics of non-fullerene acceptors (NFAs), is revealed. The alloy-like model is adopted separately into host donor and acceptor materials of the state-of-the-art binary PM6:BTP-4Cl blend with the self-stable polymer acceptor PDI-2T and small molecule donor DRCN5T as the third components, delivering the simultaneously enhanced photovoltaic efficiency and storage stability. In such ternary systems, two separate arguments can rationalize their operating principles: (1) the acceptor alloys strengthen the conformational rigidity of BTP-4Cl molecules to restrain the intramolecular vibrations for rapid relaxation of high-energy excited states to stabilize BTP-4Cl acceptor. (2) The donor alloys optimize the fibril network microstructure of PM6 polymer to restrict the kinetic diffusion and aggregation of BTP-4Cl molecules. According to the superior morphological stability, non-radiative defect trapping coefficients can be drastically reduced without forming the long-lived, trapped charge species in ternary blends. The results highlight the novel protective mechanisms of engineering the alloy-like composites for reinforcing the long-term stability of NFA-based ternary OSCs.

The solvent engineering of precursor solutions toward efficient perovskite solar cells (PSCs) is reviewed comprehensively. The key role of solvent engineering for solution‐processed perovskite film is highlighted, especially for the large‐area production of PSCs. Light is shed on the significance of solvent engineering in PSCs, and critical guidance for future commercialization development of highly efficient PSCs is provided.

Abstract

Solar cells based on emerging organic–inorganic hybrid perovskite materials have reached certified power conversion efficiency as high as 25.5%, showing great potential in the next generation of photovoltaics toward large‐scale industrialization. The most competitive feature of perovskite solar cells (PSCs) is that the perovskite light absorber can be fabricated by a low‐cost solution method. For the solution method, the characteristics of the solvent play a key role in determining the crystallization kinetics, growth orientation, and optoelectronic properties of the perovskite film. Although significant progress has been made in the field of solvent engineering in PSCs, it is still challenging for the solution method to sustainably produce industrial‐scale PSCs for future commercialization applications. Herein, the advanced progress of solvent engineering of precursor solution in terms of coordination regulation and toxicity reduction is highlighted. The physical and chemical characteristics of different solvents in reducing the toxicity of the solvent system, regulating the coordination property of the precursor solution, controlling the film‐forming process of the perovskite film, and adjusting the photovoltaic performance of the PSC are systematically discussed. Lastly, important perspectives on solvent engineering of the perovskite precursor solution toward future industrial production of high‐performance PSCs are provided.

Small‐molecule organic solar cells based on a new electron donor reach power conversion efficiencies exceeding 13% with and without the use of electrode interlayers, but differ strongly in stability. Surprisingly, the surface composition and morphology of the interlayers deteriorate with time even under inert conditions, reducing device performance. Without interlayers, the cells give stable high performance.

Abstract

Electron transport layers (ETLs) placed between the electrodes and a photoactive layer can enhance the performance of organic solar cells but also impose limitations. Most ETLs are ultrathin films, and their deposition can disturb the morphology of the photoactive layers, complicate device fabrication, raise cost, and also affect device stability. To fully overcome such drawbacks, efficient organic solar cells that operate without an ETL are preferred. In this study, a new small‐molecule electron donor (H31) based on a thiophene‐substituted benzodithiophene core unit with trialkylsilyl side chains is designed and synthesized. Blending H31 with the electron acceptor Y6 gives solar cells with power conversion efficiencies exceeding 13% with and without 2,9‐bis[3‐(dimethyloxidoamino)propyl]anthra[2,1,9‐def:6,5,10‐d′e′f ′]diisoquinoline‐1,3,8,10(2H,9H)‐tetrone (PDINO) as the ETL. The ETL‐free cells deliver a superior shelf life compared to devices with an ETL. Small‐molecule donor–acceptor blends thus provide interesting perspectives for achieving efficient, reproducible, and stable device architectures without electrode interlayers.

A new easily handled synthetic method toward N‐aryl DPPs was reported through the reaction of H‐DPP with diaryliodonium salt in the presence of CuI. The N‐aryl DPPs are fluorescent in solutions and solid states. Furthermore, the reaction can lead to π‐expanded DPPs by using Pd(OAc)₂ as catalyst. These π‐expanded DPPs exhibit good semiconducting properties, demonstrating their potential applications in organic semiconductors of high performance.

Abstract

Diketopyrrolopyrrole (DPP) as a building block has been intensively investigated for organic semiconductors and light emitting materials. The synthesis of N‐aryl DPPs remains challenging. Herein, we firstly report a new easily handled synthetic method toward N‐aryl DPPs through H‐DPP with diaryliodonium salt in the presence of CuI, which shows broad reaction scope. Sixteen N‐aryl DPPs, including phenyl, furan and thiophene as flanking aromatic groups, were synthesized with yields up to 78 %. These N‐aryl DPPs are fluorescent in both solutions and solid states, with quantum yields up to 96 % and 40 %, respectively. Moreover, we show that the reaction between H‐DPP and diaryliodonium salt can lead to π‐expanded DPPs by using Pd(OAc)₂ as catalyst. Nine π‐expanded DPPs were obtained in 27–61 % yields. These π‐expanded DPPs exhibit good semiconducting properties with hole mobility of 0.71 cm² V⁻¹ s⁻¹, demonstrating that they are useful building blocks for high performance organic semiconductors.

Three structurally similar non‐fullerene acceptors with various outer side chains are designed and matched with a cost‐effective donor polymer named PTQ10 to fabricate organic solar cells. High efficiencies of 17.1% and 17.6% are achieved by the PTQ10‐based binary and ternary devices, respectively, demonstrating the significance of material compatibility in fine‐tuning morphology toward high‐performance organic photovoltaics.

Abstract

In this work, the properties and performance of three structurally similar non‐fullerene acceptors (named BTP‐Ph, BTP‐Th, and BTP‐C11) possessing different side chains on the β‐positions of the thienothiophene units of the Y6 molecule are systematically studied. The steric and electronic effects of these side chains on the blend morphology and device performance based on the PTQ10 donor polymer are investigated. It is found that the thiophene and benzene units on the side chains introduce more steric hindrance and thus slightly reduce the crystallinity of the molecule. However, an interesting matching trend with the PTQ10 donor that appears to better match with the less crystalline molecules is observed. Overall, PTQ10:BTP‐Ph delivers the highest performance of 17.1% due to the suitable phase separation among three blends. Next, a ternary strategy is explored by incorporating BTP‐Th/BTP‐C11 with better molecular packing into PTQ10:BTP‐Ph, which successfully extends photon response, enhances charge transport, and suppresses charge recombination compared with the binary blend. Due to these synergistic effects, the ternary device based on PTQ10:BTP‐Ph:BTP‐Th achieves an outstanding power conversion efficiency of 17.6% with a fill factor of 78.8%, which is the highest value of PTQ10‐based devices to date.

Comprehensive high‐pressure experiments show that the structural and optoelectronic properties of methylammonium lead iodide perovskite (MAPbI₃) will be drastically improved when hydrogen is replaced with deuterium in the organic cation. The improved lattice stability boosts the photoluminescence intensity of MAPbI₃ by threefold. The pressure‐treated CD₃ND₃PbI₃ exhibits a nearly reversible emission properties, demonstrating its superior mechanical robustness. CD₃ND₃PbI₃‐based device also exhibits slower degradation of photovoltaic performance.

Abstract

The soft nature of organic–inorganic halide perovskites renders their lattice particularly tunable to external stimuli such as pressure, undoubtedly offering an effective way to modify their structure for extraordinary optoelectronic properties. Here, using the methylammonium lead iodide as a representative exploratory platform, it is observed that the pressure‐driven lattice disorder can be significantly suppressed via hydrogen isotope effect, which is crucial for better optical and mechanical properties previously unattainable. By a comprehensive in situ neutron/synchrotron‐based analysis and optical characterizations, a remarkable photoluminescence (PL) enhancement by threefold is convinced in deuterated CD₃ND₃PbI₃, which also shows much greater structural robustness with retainable PL after high peak‐pressure compression–decompression cycle. With the first‐principles calculations, an atomic level understanding of the strong correlation among the organic sublattice and lead iodide octahedral framework and structural photonics is proposed, where the less dynamic CD₃ND₃ ⁺ cations are vital to maintain the long‐range crystalline order through steric and Coulombic interactions. These results also show that CD₃ND₃PbI₃‐based solar cell has comparable photovoltaic performance as CH₃NH₃PbI₃‐based device but exhibits considerably slower degradation behavior, thus representing a paradigm by suggesting isotope‐functionalized perovskite materials for better materials‐by‐design and more stable photovoltaic application.

Rb₄SnSb₂Br₁₂ can unexpectedly possess fertile low formation‐energy polymorphs holding van de Walls layered structures, exhibiting a wide range of bandgap covering the visible spectrum, thus potentially working in all‐perovskite multiple‐junction tandem solar cells. It may also be possible to achieve both type‐I and type‐II band alignment in single‐compound Rb₄SnSb₂Br₁₂ heterojunctions.

Abstract

Discovering new types of layered perovskites has great importance for designing novel optoelectronic devices. In this article, combining first‐principle calculations with global structure searching, it is found that Rb₄SnSb₂Br₁₂, a typical halide double perovskite, can unexpectedly possess fertile low formation‐energy polymorphs holding van de Walls (vdW) layered structures. Consequently, these polymorphs can be effectively classified into 12 types according to their local octahedral motifs, exhibiting a wide range of bandgap covering the visible spectrum. Interestingly, the structure‐dependent bandgap in these polymorphs can be well understood by developing a simple machine learning model. Moreover, as a layered system, the optoelectronic properties of Rb₄SnSb₂Br₁₂ can be effectively tuned by the layer thickness, and both type‐I and type‐II band alignment can be achieved in single‐compound Rb₄SnSb₂Br₁₂ heterojunctions. Finally, it is suggested that the Sn‐moderate condition can be considered to grow intrinsic p‐type Rb₄SnSb₂Br₁₂ with lower defect density. Those findings not only provide a promising material system for designing the vdW tandem solar cell, but also offer a new opportunity to achieve exotic optoelectronic applications in a single‐phase layered perovskite compound.

PbSe quantum dot (QD) infrared solar cells are promising devices for improved photovoltaic performance by harvesting the low‐energy infrared photons unabsorbed by common solar cells. Here, a strategy to protect PbSe QDs is developed via combination of epitaxially coating a thin PbS shell and in situ halide passivation, breaking the V _OC–J _SC trade‐off in the traditional QD solar cells.

Abstract

Lead chalcogenide quantum dot (QD) infrared (IR) solar cells are promising devices for breaking through the theoretical efficiency limit of single‐junction solar cells by harvesting the low‐energy IR photons that cannot be utilized by common devices. However, the device performance of QD IR photovoltaic is limited by the restrictive relation between open‐circuit voltages (V _OC) and short circuit current densities (J _SC), caused by the contradiction between surface passivation and electronic coupling of QD solids. Here, a strategy is developed to decouple this restriction via epitaxially coating a thin PbS shell over the PbSe QDs (PbSe/PbS QDs) combined with in situ halide passivation. The strong electronic coupling from the PbSe core gives rise to significant carrier delocalization, which guarantees effective carrier transport. Benefited from the protection of PbS shell and in situ halide passivation, excellent trap‐state control of QDs is eventually achieved after the ligand exchange. By a fine control of the PbS shell thickness, outstanding IR J _SC of 6.38 mA cm⁻² and IR V _OC of 0.347 V are simultaneously achieved under the 1100 nm‐filtered solar illumination, providing a new route to unfreeze the trade‐off between V _OC and J _SC limited by the photoactive layer with a given bandgap.

Quadrupole moment induced morphology control in organic solar cells is realized by a highly volatile solid molecule (DTBF). The presence of a strong charge‐quadrupole interaction among the DTBF‐processed active layer can effectively alter the morphology and introduce beneficial optoelectronic properties. This work realizes a high efficiency of over 17% and provides a design guideline for efficient solid additives.

Abstract

Developing novel solid additives has been regarded as a promising strategy to achieve highly efficient organic solar cells with good stability and reproducibility. Herein, a small molecule, 2,2′‐(perfluoro‐1,4‐phenylene)dithiophene (DTBF), designed with high volatility and a strong quadrupole moment, is applied as a solid additive to implement active layer morphology control in organic solar cells. Systematic theory simulations have revealed the charge distribution of DTBF and its analog and their non‐covalent interaction with the active layer materials. Benefitting from the more vital charge–quadrupole interaction, the introduction, and volatilization of DTBF effectively induced more regular and condensed molecular packing in the active layer, leading to enhanced photoelectric properties. Thus, high efficiency of over 17% is obtained in the DTBF‐processed devices, which is higher than that of the control devices. Further application of DTBF in different active layer systems contributed to a deeper comprehension of this type of additive. This study highlights a facile approach to optimizing the active layer morphology by finely manipulating the quadrupole moment of volatile solid additives.

The exploration of conjugated polymers for non-fullerene acceptor organic photovoltaics guided by machine learning (ML) is reported. An ML model is constructed based on the random forest algorithm using experimental data reported in the literature and used to virtually screen 200k polymers. The high prediction accuracy, experimental feedback, and manual consideration make this ML strategy an effective alternative for trial-and-error experiments.

Abstract

Despite the capacity of conjugated materials for enhanced power conversion efficiency (PCE) of organic photovoltaics (OPV), a comprehensive survey of unexplored materials is beyond the reach of most researchers’ resources. In such instances, a data-driven approach using machine learning (ML) is an efficient alternative; however, bridging the gap between experimental observations and data science requires a number of refinements. In this investigation, using a random forest model based on an experimental dataset, a high correlation coefficient of 0.85 is achieved for the ML of polymer and non-fullerene small molecule acceptor OPVs and performed virtual screening of 200,932 conjugated polymers generated by the combinatorial coupling of donor and acceptor units. Further, to evaluate the effectiveness of the ML model, a series of conjugated polymers (based on benzodithiophene and thiazolothiazole) were designed, synthesized, and characterized with different alkyl chains. Among these, PBDTTzEH:IT-4F showed a PCE of 10.10%, which is in good correspondence with ML predictions with respect to the choice of alkyl chains. Thus, the current study demonstrates how ML can be utilized for developing OPVs using a relatively small number of experimental data points (566) and screening numerous molecular structures.

Polycrystalline all‐inorganic CsPbI_{3− x} Br _x perovskite exhibits pervasive texture expressions when solution processed into thin‐film optical devices. Synchrotron‐based large‐area X‐ray scattering techniques provide insights, which connect the final texture formation to the crystal symmetry of the halide perovskite, which can be tuned via halide mixing. Both I‐rich and Br‐rich materials each exhibit two different, energetically favored texture directions.

Abstract

Controlling grain orientations within polycrystalline all‐inorganic halide perovskite solar cells can help increase conversion efficiencies toward their thermodynamic limits; however, the forces governing texture formation are ambiguous. Using synchrotron X‐ray diffraction, mesostructure formation within polycrystalline CsPbI_2.85Br_0.15 powders as they cool from a high‐temperature cubic perovskite (α‐phase) is reported. Tetragonal distortions (β‐phase) trigger preferential crystallographic alignment within polycrystalline ensembles, a feature that is suggested here to be coordinated across multiple neighboring grains via interfacial forces that select for certain lattice distortions over others. External anisotropy is then imposed on polycrystalline thin films of orthorhombic (γ‐phase) CsPbI_{3‐ x} Br _x perovskite via substrate clamping, revealing two fundamental uniaxial texture formations; i) I‐rich films possess orthorhombic‐like texture (<100> out‐of‐plane; <010> and <001> in‐plane), while ii) Br‐rich films form tetragonal‐like texture (<110> out‐of‐plane; <110> and <001> in‐plane). In contrast to relatively uninfluential factors like the choice of substrate, film thickness, and annealing temperature, Br incorporation modifies the γ‐CsPbI_{3− x} Br _x crystal structure by reducing the orthorhombic lattice distortion (making it more tetragonal‐like) and governs the formation of the different, energetically favored textures within polycrystalline thin films.

A charge‐transfer complex strategy to reduce the energy disorder of organic semiconductor (OS) charge transport layers (CTLs) by doping a well‐designed OS (BDT‐Si) with electron‐acceptor features in a commercial hole‐transport material (PTAA) is proposed. As a result, the p–i–n planar perovskite solar cells with the optimized hole‐transport layer exhibit the best power conversion efficiency of 21.87%, and good operating stability at maximum power point under continuous illumination.

Abstract

Solution‐processed organic semiconductor charge‐transport layers (OS‐CTLs) with high mobility, low trap density, and energy level alignment have dominated the important progress in p–i–n planar perovskite solar cells (pero‐SCs). Unfortunately, their inevitable long chains result in weak molecular stacking, which is likely to generate high energy disorder and deteriorate the charge‐transport ability of OS‐CTLs. Here, a charge‐transfer complex (CTC) strategy to reduce the energy disorder in the OS‐CTLs by doping an organic semiconductor, 4,4′‐(4,8‐bis(5‐(trimethylsilyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(N,N‐bis(4‐methoxyphenyl)aniline) (BDT‐Si), in a commercial hole‐transport layer (HTL), poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl)amine (PTAA), is proposed. The formation of the CTC makes the PTAA conjugated backbone electron‐deficient, resulting in a quinoidal and stiffer character, which is likely to planarize the PTAA backbone and enhance the ordering of the film in nanoscale. The resultant HTL exhibits a reduced energy disorder, which simultaneously promotes hole transport in the HTL, hole extraction at the interface, energy level alignment, and quasi‐Fermi level splitting in the device. As a result, the p–i–n planar pero‐SCs with optimized HTL exhibit the best power conversion efficiency of 21.87% with good operating stability. This finding demonstrates that the CTC strategy is an effective way to reduce the energy disorder in HTLs and to improve the performance of planar pero‐SCs.