Perovskite Precursor Solution Research Articles

Postdeposition Halide Exchange for Achieving Deep-Blue Perovskite Light-Emitting Diodes: The Role of the Organic Cations in the Chloride Source.

Postdeposition halide exchange has been a popular strategy for tuning the emission wavelength of metal halide perovskites and is particularly attractive in achieving deep-blue perovskite light-emitting diodes (PeLEDs), where the quality of the emissive layer is largely limited by the low solubility of chlorides in perovskite precursor solution. In this work, the halide exchange strategy isexamined for deep-blue PeLEDs, with a focus on understanding the role of the organic cations of the halide salt (i.e., the chloride source for ion exchange) in modifying the properties of the perovskite films and consequently the PeLED performances. By comparatively investigating the treatment effects of two model systems, namely phenethylammonium chloride and 2,2-diphenylethylammonium chloride (DPEACl), it isfound that although the two chlorides produce highly similar photoluminescence properties of the perovskite films, they create different landscapes for current flow in the PeLEDs. In particular, the bulky branch-structured DPEA cations exhibit minimal disturbance to the perovskite grains while providing highly effective inter-grain void filling and thus leakage current blocking, leading to 3D perovskite-based PeLEDs with a record high peak external quantum efficiency of 6.4% at 462nm. The study highlights the importance of organic cation selection in the halide exchange processes for PeLEDs.

Long-Chain Gemini Surfactant-Assisted Blade Coating Enables Large-Area Carbon-Based Perovskite Solar Modules with Record Performance

HighlightsTrace amounts of long-chain gemini surfactants are essential for blade-coating of high-quality perovskite films, enabling a 17.05% efficient full printed carbon-based module (50 cm2 active area).Only when the surfactant chain is over a critical length will the gemini surfactant be effective for blade-coating of perovskite films.The surfactants increase the capillary number of perovskite precursor solution, reduce the local disturbance and combat inhomogeneous solidification during blade coating, thus allowing high-quality perovskite films to be formed.

Perovskite solar cell fabrication via scalable thermal‐assisted and meniscus‐guided bar‐coating method in open air

AbstractBackgroundPerovskite‐based solar cell is getting great attention as a promising candidate for future solar cell technology, since high power conversion efficiency above 25.5% have been demonstrated for small scale PSCs from films prepared mainly by spin‐coating method, which is not feasible for large area film preparation. Scalable and cost‐effective film fabrication techniques are urgently needed for the commercialization of perovskite solar cells.ObjectiveTo develop a process from which large‐area, high quality and unifoem perovskite films, as well as the hole‐transporting layer films, can be prepared in a simple and cheap way for the practical application and mass production of perovskite solar cells.MethodsLarge‐area electron‐transporting layer layers of mp‐TiO2 and c‐TiO2 were prepared on the FTO substrate by the solution‐shearing method. Then the 10 × 10 cm2 perovskite film was prepared by using a bar‐coater from perovskite precursor solution in ACN/MA solvent system under optimized conditions. The spiro‐OMeTAD film was also prepared by bar‐coating process. Standard‐sized pieces (1.5 × 1.8 cm2) were cut and the Ag metal electrode (80 nm) was deposited through a shadow mask in a thermal evaporation system for device evaluation.ResultsThe large crystalline grains and pinhole‐free perovskite film obtained were fully characterized to show better film properties compared to that from the spin‐coated film, and appeared less sensitive to moisture. A higher PCE of 19.72% was achieved for standard‐sized devices fabricated from the bar‐coated perovskite film with spiro‐OMeRAD film spin‐coated on top, or an excellent PCE of 18.10% was obtained with bar‐coated spiro‐OMeTAD layer on top.ConclusionsThis work demonstrates that the simple and scalable process of bar‐coating can offer high quality and homogeneous films of perovskite and spiro‐OMeTAD respectively. It is compatible with the R2R process and useful in realizing the commercialization of PSC technology.

A Blue-Light-Emitting 3 nm-Sized CsPbBr3 Perovskite Quantum Dot with ZnBr2 Synthesized by Room-Temperature Supersaturated Recrystallization

Recently, tuning the green emission of CsPbBr3 quantum dots (QDs) to blue through quantum size and confinement effects has received considerable attention due to its remarkable photophysical properties. However, the synthesis of such a blue-emitting QD has been challenging. Herein, supersaturated recrystallization was successfully implemented at room temperature to synthesize a broadband blue-emitting ZnBr2-doped CsPbBr3 QD with an average size of ~3 nm covering the blue spectrum. The structural and optical properties of CsPbBr3 QDs demonstrated that QD particle size may decrease by accommodating ZnBr2 dopants into the perovskite precursor solution. Energy-dispersive spectroscopy confirmed the presence of zinc ions with the QDs. This work provides a new strategy for synthesizing strongly quantum-confined QD materials for photonic devices such as light-emitting diodes and lighting.

Conjugated small molecule inhibiting intrinsic ion migration and enriching electron transfer channels for stable and efficient perovskite solar cells

Generally, efficient and stable perovskite solar cells (PSCs) have the following characteristics: 1) less ion migration; 2) large perovskite grain size; 3) low defect state density; 4) efficient charge transfer and inhibited carrier recombination. Herein, this work reports a facile strategy of incorporating π-conjugated tetrafluoroterephthalonitrile (C8N2F4, abbreviated to CNF) into perovskite precursor solution for high-quality thin film. Surprisingly, the π-conjugated CNF molecule can realize the above characteristics at the same time. As a result, the champion PSC yields a power conversion efficiency (PCE) of 22.44% as well as a stabilized PCE of 21.77%. Further, the CNF-doped PSC (unencapsulated) retains 91.62% of its initial PCE after exposed to moist air (relative humidity: 50–80%) for 1500 h and shows excellent thermal stability (T80 > 1200 h) at 85 °C. The increased stability is due to the cation migration inhibition and the PbI (I site substitution by Pb) and IPb (Pb site substitution by I) defect passivation of perovskite after the incorporation of π-conjugated CNF molecule. Our results can deepen the understanding of organic small molecules for potential applications in improving the device PCE and the operation and long-term stability of PSC.

Enhancing the Performance of Perovskite Solar Cells by Introducing 4-(Trifluoromethyl)-1H-imidazole Passivation Agents.

Defects in perovskite films are one of the main factors that affect the efficiency and stability of halide perovskite solar cells (PSCs). Uncoordinated ions (such as Pb2+, I-) act as trap states, causing the undesirable non-radiative recombination of photogenerated carriers. The formation of Lewis acid-base adducts in perovskite directly involves the crystallization process, which can effectively passivate defects. In this work, 4-(trifluoromethyl)-1H-imidazole (THI) was introduced into the perovskite precursor solution as a passivation agent. THI is a typical amphoteric compound that exhibits a strong Lewis base property due to its lone pair electrons. It coordinates with Lewis acid Pb2+, leading to the reduction in defect density and increase in crystallinity of perovskite films. Finally, the power conversion efficiency (PCE) of PSC increased from 16.49% to 18.97% due to the simultaneous enhancement of open-circuit voltage (VOC), short circuit current density (JSC) and fill factor (FF). After 30 days of storage, the PCE of the 0.16 THI PSC was maintained at 61.9% of its initial value, which was 44.3% for the control device. The working mechanism of THI was investigated. This work provides an attractive alternative method to passivate the defects in perovskite.

Cationic and Anionic Vacancy Healing for Suppressed Halide Exchange and Phase Segregation in Perovskite Solar Cells

All-inorganic wide-bandgap (WBG) perovskite solar cells are best suited as the top cells for tandem devices. However, they suffer from photoinduced halide segregation (PIHS) and a quick anion exchange reaction (AER). Herein, polyvinylpyrrolidone (PVP) polymer-assisted in situ crystalization of CsPbBr3 and CsPbBr1.5I1.5 compounds is shown to suppress these effects by passivation of both positively charged (halide vacancy) and negatively charged (cation vacancy) defects. Modifying the perovskite precursor solution with this polymer improved the chemical stability and photostability in both nanocrystal solution and solution-processed films. Ultrafast transient absorption measurements elucidate the excited state dynamics of PVP-modified perovskite and probe an improved lifetime of charge carriers. As a proof of concept, PVP-modified CsPbI1.5Br1.5 retained nearly 98% Voc and 90% PCE under 1 sun AM 1.5G illumination for 12 h, while the control devices lost 25% of their Voc within 6 h. Using simple polymer additives to protect WBG perovskites is a huge step toward new device architectures involving all-perovskite heterojunctions.

Sol-Gel Prepared Spinel HTLs for Assembling 20% Efficiency Perovskite Solar Cell in Air Without Using Anti-Solvent and Toxic Solvent.

Low-temperature sol-gel prepared ZnCo2 O4 spinel-based thin films are developed as high-performance hole transporting layer (HTL) for coating perovskite film (NA-Psk) from the basic MAPbI3 /ACN/CH3 NH2 solution in air without using anti-solvent. Inverted PSC based on 2mole% (vs Zn) Cu2+ doped ZnCo2 O4 (2%Cu@ZnCo2 O4 ) HTL and NA-Psk absorber exhibit the maximum power conversion efficiency (PCE) of 20.0% with no current hysteresis while the cell based on ZnCo2 O4 and PEDOT:PSS HTL (using NA-Psk absorber) achieves the PCE of 15.79% and 12.3% with a current hysteresis index of 9.8% and 32.4%, respectively. Without encapsulation, PSCs based on 2%Cu@ZnCo2 O4 , ZnCo2 O4 , and PEDOT:PSS HTLs maintain 90%, 77%, and 12%, respectively of the original efficiency by standing in ambient atmosphere (temperature: 20-25°C, RH:30%-40%) for 1800h. Large area (10cm× 10cm substrate) perovskite mini-module (PSM) with PCE over 15% is also demonstrated by using sol-gel prepared 2%Cu@ZnCo2 O4 HTL. The poor photovoltaic performance of PEDOT:PSS HTL is due to the basic MAPbI3 /ACN/CH3 NH2 solution will deprotonate the acidic PEDOT:PSS to reduce its conductivity whereas ZnCo2 O4 HTL are not affected by basic perovskite precursor solution.

Chemical Reduction of Iodine Impurities and Defects with Potassium Formate for Efficient and Stable Perovskite Solar Cells

AbstractThe performance of perovskite solar cells (PSCs) is negatively affected by iodine (I2) impurities generated from the oxidation of iodide ions in the perovskite precursor powder, solution, and perovskite films. In this study, the use of potassium formate (HCOOK) as a reductant to minimize the presence of detrimental I2 impurities is presented. It is demonstrated that HCOOK can effectively reduce I2 back to I− in the precursor solution as well as in the devices under external conditions. Furthermore, the introduced formate anion (HCOO−) and alkali metal cation (K+) can reduce the defect density within the perovskite film by modulating perovskite growth and passivating electronic defects, significantly prolonging the carrier lifetime and reducing the J–V hysteresis. Consequently, the maximum efficiency of the HCOOK‐doped planar n–i–p PSCs reaches 23.8%. After 1000 h of operation at maximum power point tracking under continuous 1 sun illumination, the corresponding encapsulated devices retain 94% of their initial efficiency.

Mixed Organic Cations Promote Ambient Light-Induced Formation of Metallic Lead in Lead Halide Perovskite Crystals.

One major concern toward the performance and stability of halide perovskite-based optoelectronic devices is the formation of metallic lead that promotes nonradiative recombination of charge carriers. The origin of metallic lead formation is being disputed whether it occurs during the perovskite synthesis or only after light, electron, or X-ray beam irradiation or thermal annealing. Here, we show that the quantity of metallic lead detected in perovskite crystals depends on the concentration and composition of the precursor solution. Through a controlled crystallization process, we grew black-colored mixed dimethylammonium (DMA)/methylammonium (MA) lead tribromide crystals. The black color is suggested to be due to the presence of small lead clusters. Despite the unexpected black coloring, the crystals show higher crystallinity and less defect density with respect to the standard yellow-colored DMA/MAPbBr3 crystals, as indicated by X-ray rocking curve and dark current measurements, respectively. While the formation of metallic lead could still be induced by external factors, the precursor solution composition and concentration can facilitate the formation of metallic lead during the crystallization process. Our results indicate that additional research is required to fully understand the perovskite precursor solution chemistry.

Role of Dibenzo Crown Additive for Improving the Stability of Inorganic Perovskite Solar Cells.

Photovoltaics are being transformed by perovskite solar cells. The power conversion efficiency of these solar cells has increased significantly, and even higher efficiencies are possible. The scientific community has gained much attention due to perovskites' potential. Herein, the electron-only devices were prepared by spin-coating and introducing the organic molecule dibenzo-18-crown-6 (DC) to CsPbI2Br perovskite precursor solution. The current-voltage (I-V) and J-V curves were measured. The morphologies and elemental composition information of the samples were obtained by SEM, XRD, XPS, Raman, and photoluminescence (PL) spectroscopies. The distinct impact of organic DC molecules on the phase, morphology, and optical properties of perovskite films are examined and interpreted with experimental results. The efficiency of the photovoltaic device in the control group is 9.76%, and the device efficiency gradually increases with the increase of DC concentration. When the concentration is 0.3%, the device efficiency is the best, reaching 11.57%, short-circuit current is 14.01 mA/cm2, the open circuit voltage is 1.19 V, and the fill factor is 0.7. The presence of DC molecules effectively controlled the perovskite crystallization process by inhibiting the in-situ generations of impurity phases and minimizing the defect density of the film.

Numerical Simulation on Preparing Uniform and Stable Perovskite Wet Film in Slot-Die Coating Process.

Slot-die coating is regarded as a reliable and potential technology for preparing large-area perovskite solar cells with high efficiency and low cost. Therein, the formation of continuous and uniform wet film is of significance to obtain a high-quality solid perovskite film. In this work, the rheological properties of the perovskite precursor fluid are analyzed. Then, the ANSYS Fluent is introduced to establish an integrated model of internal and external flow fields during the coating process. The model is applicable to all perovskite precursor solutions with near-Newtonian fluids. Based on the theoretical simulation of finite element analysis, the preparation of 0.8 M-FAxCs1-xPbI3, one of the typical large-area perovskite precursor solutions, is explored. Accordingly, this work indicates that the coupling process parameters like the fluid supply velocity (Vin) and coating velocity (V) determine the uniformity that the solution flows out of the slit and is coated onto the substrates, and the coating windows for a uniform and stable perovskite wet film is obtained. For the upper boundary range of the coating windows, the maximum value of V and Vin follows V = 0.003 + 1.46Vin (Vin ≤ 0.1 m/s), while for its lower boundary range, the minimum value of V and Vin is V = 0.002 + 0.67Vin (Vin ≤ 0.1 m/s). When Vin is higher than 0.1 m/s, the film will break due to the excessive V. Finally, the real experiment verifies the accuracy of the numerical simulation. Hopefully, this work is of reference value for the development of the slot-die coating forming process on the perovskite precursor solution approximating Newtonian fluid.

Interfacial and Doping Synergistic Effect of Versatile Potassium Acetate toward Efficient CsPbI2Br Perovskite Solar Cells

The functional material-based interface and additive engineering are considered as valid approaches to enhance the photovoltaic performance of perovskite solar cells (PSCs). However, most of these materials have been reported to play only one role in PSCs. Herein, we applied versatile potassium acetate (KAc) as the cathode buffer layer (CBL), electron transporting layer (ETL), and perovskite additive in all-inorganic CsPbI2Br PSCs, respectively. All the KAc-incorporated devices yield higher efficiency than the control device. Especially, we achieve the interfacial and doping synergistic effects by introducing KAc CBL between SnO2 ETL and CsPbI2Br perovskite. For the interfacial effect, the KAc CBL can passivate the Sn-related defects and optimize the interfacial energy-level alignment at the SnO2/CsPbI2Br contact. For the doping effect, KAc is partially doped into CsPbI2Br during spin-coating of the perovskite precursor solution due to its good solubility in the solvent of perovskite precursor, which results in the passivation of uncoordinated Pb2+ in the perovskite layer. Owing to the interfacial and doping synergistic effect, the power conversion efficiency (PCE) increases noticeably from 12.91% to 15.71% after inserting KAc CBL. Furthermore, the device with KAc CBL exhibits superior long-term thermal stability. The findings offer a versatile material to simultaneously passivate interfacial and bulk defects and thus enhance the performance of all-inorganic PSCs.

Simultaneously Achieved Defect Passivation and Crystallization Modulation by a Multifunctional Pseudohalogen Salt for Efficient and Stable Perovskite Solar Cells

The accumulation of defects and ion migration at the surfaces and grain boundaries of perovskite impedes the improvement of performance and stability in perovskite solar cells. Therefore, developing strategies to reduce trap‐assisted nonradiative recombination and suppress ion migration in perovskite films is urgently needed. Herein, a multifunctional pseudohalogen salt additive, (benzotriazol‐1‐yloxy) dipyrrolidinocarbenium hexafluorophosphate (denoted as BDPF6), composed of a benzotriazole derivative cation and hexafluorophosphate anion, is incorporated into the perovskite precursor solution. The anion vacancies of perovskite films are filled by , whereas the cation and anion in BDPF6 form ionic and coordination bonds with the perovskites. The BDPF6 additive promotes the crystallization of perovskite films with large grain size, reducing defect densities, prolonging carrier lifetimes, and inhibiting ion migration. Thus, the power conversion efficiency (PCE) of the BDPF6‐modified device remarkably improves from 20.36% to 22.68%. The unencapsulated BDPF6‐modified device maintains 97% of its initial PCE after 1,400 h of exposure to an ambient environment with a relative humidity of 10–20%, whereas the control device maintains only 85% of its initial PCE. Similarly, the BDPF6‐modified device maintains 78% of its original PCE after aging at 60 °C for 1,400 h, whereas the control device only maintains 55%.

Buried Interface Modulation via Preferential Crystallization in All‐Inorganic Perovskite Solar Cells: The Case of Multifunctional Ti3C2Tx

AbstractDespite inorganic CsPbI3−xBrx perovskite solar cells (PSCs) being promising in thermal stability, the perovskite degradation and severe nonradiative recombination at the interface hamper their further development. Herein, the typical MXene material, that is, Ti3C2Tx, is employed to be the buried interface prior to the perovskite absorber layer in the device, which multi‐functionalizes the as‐prepared electron‐transfer layers by means of both fascinating preferential crystallization of perovskite and/or accelerating the charge extraction with respect to an ideal energy‐level alignment and suppressed trap states. Accordingly, the power conversion efficiency of the modified PSC device is substantially enhanced by as high as 19.56% in comparison to their counterparts with only the pristine CsPbI3−xBrx active layer. More importantly, MXene modification is favorable to improve the wettability of perovskite precursor solution with enhanced grain size and crystallinity, thereby increasing the UV long‐term stability of solar cells. This work provides a new paradigm toward alleviating the severe nonradiative recombination at the interface in the device whilst enhancing the long‐term stability via the preferential crystallization process.

Mixed-Cation Halide Perovskite Doped with Rb+ for Highly Efficient Photodetector.

Photodetectors are widely employed as fundamental devices in optical communication, automatic control, image sensors, night vision, missile guidance, and many other industrial or military fields. Mixed-cation perovskites have emerged as promising optoelectronic materials for application in photodetectors due to their superior compositional flexibility and photovoltaic performance. However, their application involves obstacles such as phase segregation and poor-quality crystallization, which introduce defects in perovskite films and adversely affect devices' optoelectronic performance. The application prospects of mixed-cation perovskite technology are significantly constrained by these challenges. Therefore, it is necessary to investigate strategies that combine crystallinity control and defect passivation to obtain high-quality thin films. In this study, we incorporated different Rb+ ratios in triple-cation (CsMAFA) perovskite precursor solutions and studied their effects on crystal growth. Our results show that a small amount of Rb+ was enough to induce the crystallization of the α-FAPbI3 phase and suppress the formation of the yellow non-photoactive phase; the grain size increased, and the product of the carrier mobility and the lifetime (μτ) improved. As a result, the fabricated photodetector exhibited a broad photo-response region, from ultraviolet to near-infrared, with maximum responsivity (R) up to 11.8 mA W-1 and excellent detectivity (D*) values up to 5.33 × 1011 Jones. This work provides a feasible strategy to improve photodetectors' performance via additive engineering.

Cellulose acetate-derived ternary-doped hierarchically porous carbons blended perovskite active layers for solar cells and X-ray detectors

Herein, we have synthesized hetero-atoms (nitrogen (N), sulfur (S), phosphorus (P))-doped porous carbons (PCs) which upon dispersion in perovskite precursor solution with different (2–8 wt.%) modify its morphology and improve optoelectronic characteristics of the perovskite active layer (AL) results into enhancing efficiency and stability of perovskite solar cells (PSCs). The results indicate that PCs (6 wt.%) modifies perovskite AL-constructed PSCs and X-ray photodetectors outperform other investigated devices. The excellent PSCs (AL@NSPCPC) demonstrate power conversion efficiency (PCE) of 13.81%, fill factor (FF) 64.77%, current density Jsc (23.518 mA/cm2), and open circuit voltage Voc (0.906 V), which is significantly higher than pristine AL 10.42%, 57.01%, 20.423 mA/cm2, and 0.895 V, respectively. Furthermore, the sample (AL@NSP-CPC) when constructs in the geometry of an X-ray photodetector, shows 15.56 μA/cm2, 4.66 mA/Gy·cm2, 5.26×10−4 cm2/V·s, and 3.58 × 1015 cm−3 of collected charge density (CCD), dark current density (DCD), sensitivity, mobility, and trap density, respectively. Thus, heteroatom-doped PCs modified perovskite layers demonstrate promise for constructing PSCs and X-ray photodetectors opening future research in exploiting these abundant, and inexpensive carbons materials having large mobility and tunable morphology along with surface passivation at perovskite/hole transport layer (HTL) interface to further enhance their photovoltaic parameters.

Surface-bulk-passivated perovskite films via 2-thiophenemethylammonium bromide and PbBr2 for air-processed perovskite solar cells with high-stability

Suppressing non-radiative recombination induced by defect is of much concern to efficient and stable perovskite solar cells (PSCs). We report a cooperative strategy to passivate both interfacial and bulk defects in perovskite layer by coupling interface engineering and additive engineering. 2-Thiophenemethylammonium bromide (2-ThMAB) is synthesized by recrystallization. PbBr2 used as an additive is introduced into the perovskite precursor solution. 2-ThMAB features with an electron-rich π-system and 2-thiophene group. Br− ions have an impact on perovskite lattice reorganization. The synergistic modification of 2-ThMAB and PbBr2 enables the external electronic state modulation and internal bandgap adjustment of perovskite, which is beneficial to passivate defect and inhibit ion migration. As a result, a modified PSC exhibits a high-power conversion efficiency of 20.01% with negligible hysteresis for an all-air-processed device. More importantly, a non-encapsulated device exhibits excellent long-term stability of T98 of > 720 h. This study thus provides a new way to obtain highly stable all-air-processed PSCs..

Self‐Assembled Molecule Doping Enables High‐Efficiency Hole‐Transport‐Layer‐Free Perovskite Light‐Emitting Diodes

AbstractHole‐transport‐layer‐free (HTL‐free) perovskite light‐emitting diodes (PeLEDs) are attracting increasing research attention because of their simplified device structure, fast preparation process, and high cost effectiveness. However, their much lower external quantum efficiency (EQE) as compared with the conventional p‐i‐n type ones has considerably limited their application prospects. Here, a self‐assembled molecule (SAM) doping strategy is proposed by introducing [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) butyl] phosphonic acid (Me‐4PACz) containing PO functional groups into the perovskite precursor solution and preparing the HTL‐free quasi‐2D perovskite films through the one‐step spin‐coating process. The doped Me‐4PACz molecules can not only accumulate at the ITO/perovskite interface to lower the hole injection barrier, but also extend deep into the perovskite layer to suppress the trap density in perovskite films and regulate the crystallization process for monodispersed phase composition. With the further addition of ethoxylated trimethylolpropane triacrylate small molecule containing CO groups to passivate the defects synergistically with Me‐4PACz, the EQE of the corresponding device is boosted from 1.5% to 16.7% together with a 3.5‐fold increase in operational stability, which is the highest efficiency reported so far for HTL‐free PeLEDs. The results demonstrate that the SAM doping strategy can be a viable and facile way to prepare high‐performance HTL‐free PeLEDs for practical applications.

Regulating the Solvent Resistance of Hole Transport Layer for High‐Performance Inverted Perovskite Solar Cells

The hole transport materials (HTMs) play important roles in transporting holes and regulating perovskite crystallization in inverted perovskite solar cells (PSCs). Concerning the solubility of small‐molecule‐type HTMs in perovskite precursor solution during fabrication, the strategies including tailoring and crosslinking have been developed. However, how these strategies will influence the solvent resistance of the resultant hole transport layers (HTLs) and the corresponding device performance have not been systematically evaluated. Herein, upon incorporating tailoring and crosslinking groups into diazafluorene backbones, AFL‐COOH and AFL‐ENE are designed. Compared to the control HTM (AFL‐3) with poor solvent resistance and AFL‐COOH, the best solvent resistance of crosslinked AFL‐ENE (AFL‐ENE‐CL) film leads to an HTL with the highest quality covered on electrode, which thus results in the lowest trap density, best surface contact, and hole extraction for devices involving the AFL‐ENE‐CL type HTL and the best power conversion efficiency of 20.8% (20.0% for AFL‐COOH, 18.1% for AFL‐3). Furthermore, high reproducibility and stabilities also realize for the AFL‐ENE‐CL‐based PSC.