Diammonium and Monoammonium Mixed‐Organic‐Cation Perovskites for High Performance Solar Cells with Improved Stability

Remarkable power conversion efficiencies (PCE) of metal–halide perovskite solar cells (PSCs) are overshadowed by concerns about their ultimate stability, which is arguably the prime obstacle to commercialization of this promising technology. Herein, the problem is addressed by introducing ethane‐1,2‐diammonium (⁺NH₃(CH₂)₂NH₃⁺, EDA²⁺) cations into the methyl ammonium (CH₃NH₃⁺, MA⁺) lead iodide perovskite, which enables, inter alia, systematic tuning of the morphology, electronic structure, light absorption, and photoluminescence properties of the perovskite films. Incorporation of <5 mol% EDA²⁺ induces strain in the perovskite crystal structure with no new phase formed. With 0.8 mol% EDA²⁺, PCE of the MAPbI₃‐based PSCs (aperture of 0.16 cm²) improves from 16.7% ± 0.6% to 17.9% ± 0.4% under 1 sun irradiation, and fabrication of larger area devices (aperture 1.04 cm²) with a certified PCE of 15.2% ± 0.5% is demonstrated. Most importantly, EDA²⁺/MA⁺‐based solar cells retain 75% of the initial performance after 72 h of continuous operation at 50% relative humidity and 50 °C under 1 sun illumination, whereas the MAPbI₃ devices degrade by approximately 90% within only 15 h. This substantial improvement in stability is attributed to the steric and coulombic interactions of embedded EDA²⁺ in the perovskite structure.     

Over 17% Efficiency Stand‐Alone Solar Water Splitting Enabled by Perovskite‐Silicon Tandem Absorbers

Realizing solar‐to‐hydrogen (STH) efficiencies close to 20% using low‐cost semiconductors remains a major step toward accomplishing the practical viability of photoelectrochemical (PEC) hydrogen generation technologies. Dual‐absorber tandem cells combining inexpensive semiconductors are a promising strategy to achieve high STH efficiencies at a reasonable cost. Here, a perovskite photovoltaic biased silicon (Si) photoelectrode is demonstrated for highly efficient stand‐alone solar water splitting. A p⁺nn⁺ ‐Si/Ti/Pt photocathode is shown to present a remarkable photon‐to‐current efficiency of 14.1% under biased condition and stability over three days under continuous illumination. Upon pairing with a semitransparent mixed perovskite solar cell of an appropriate bandgap with state‐of‐the‐art performance, an unprecedented 17.6% STH efficiency is achieved for self‐driven solar water splitting. Modeling and analysis of the dual‐absorber PEC system reveal that further work into replacing the noble‐metal catalyst materials with earth‐abundant elements and improvement of perovskite fill factor will pave the way for the realization of a low‐cost high‐efficiency PEC system.     

Bandgap Engineering Enhances the Performance of Mixed‐Cation Perovskite Materials for Indoor Photovoltaic Applications

Indoor photovoltaics (IPVs) are attracting renewed interest because they can provide sustainable energy through the recycling of photon energy from household lighting facilities. Herein, the Shockley–Queisser model is used to calculate the upper limits of the power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) for two types of artificial light sources: fluorescent tubes (FTs) and white light–emitting diodes (WLEDs). An unusual zone is found in which the dependence of the PCEs on the bandgap (E_g) under illumination from the indoor lighting sources follows trends different from that under solar irradiation. In other words, IPVs exhibiting high performance under solar irradiation may not perform well under indoor lighting conditions. Furthermore, the ideal bandgap energy for harvesting photonic power from these indoor lighting sources is ≈1.9 eV—a value higher than that of common perovskite materials (e.g., for CH₃NH₃PbI₃). Accordingly, Br^? ions are added into the perovskite films to increase their values of E_g. A resulting PeSC featuring a wider bandgap exhibits PCEs of 25.94% and 25.12% under illumination from an FT and a WLED, respectively. Additionally, large‐area (4 cm²) devices are prepared for which the PCE reaches ≈18% under indoor lighting conditions.     

Trap States,Electric Fields,and Phase Segregation in Mixed‐Halide Perovskite Photovoltaic Devices

Mixed‐halide perovskites are essential for use in all‐perovskite or perovskite–silicon tandem solar cells due to their tunable bandgap. However, trap states and halide segregation currently present the two main challenges for efficient mixed‐halide perovskite technologies. Here photoluminescence techniques are used to study trap states and halide segregation in full mixed‐halide perovskite photovoltaic devices. This work identifies three distinct defect species in the perovskite material: a charged, mobile defect that traps charge‐carriers in the perovskite, a charge‐neutral defect that induces halide segregation, and a charged, mobile defect that screens the perovskite from external electric fields. These three defects are proposed to be MA⁺ interstitials, crystal distortions, and halide vacancies and/or interstitials, respectively. Finally, external quantum efficiency measurements show that photoexcited charge‐carriers can be extracted from the iodide‐rich low‐bandgap regions of the phase‐segregated perovskite formed under illumination, suggesting the existence of charge‐carrier percolation pathways through grain boundaries where phase‐segregation may occur.     

Extrinsic Movable Ions in MAPbI3 Modulate Energy Band Alignment in Perovskite Solar Cells

Ionic movement is considered awful in perovskite solar cells (PSCs) for relating with the hysteresis and long‐term instability. However, the positive role of ions to enhance the energy band bending for high performance PSC is always overlooked, let alone reducing the hysteresis. In this work, LiI is doped in CH₃NH₃PbI₃. It is observed that the aggregation of Li⁺/I^? tunes the energy level of the perovskite and induces n/p doping in CH₃NH₃PbI₃, which makes charge extraction quite efficient from perovskite to both NiO and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) layer. Therefore, in NiO/LiI doped perovskite/PCBM solar cells, Li⁺ and I^? modulate the interface energy band alignment to facilitate the electron/hole transport and reduce the interface energy loss. On the other hand, n/p doping enlarges Fermi energy level splitting of the PSCs to improve the photovoltage. The performance of LiI doped PSCs is much higher with reduced hysteresis compared to the undoped solar cells. This work highlights the positive effect of selective ionic doping, which is promisingly important to design the stable and efficient PSCs.     

Long‐Lasting Nanophosphors Applied to UV‐Resistant and Energy Storage Perovskite Solar Cells

Recently, considerable progress is achieved in lab prototype perovskite solar cells (PSCs); however, the stability of outdoor applications of PSCs remains a challenge due to the high sensitivity of perovskite material under moist and ultraviolet (UV) light conditions. In this work, the UV photostability of PSC devices is improved by incorporating a photon downshifting layer—SrAl₂O₄: Eu²⁺, Dy³⁺ (SAED)—prepared using the pulsed laser deposition approach. Light‐induced deep trap states in the photoactive layer are depressed, and UV light‐induced device degradation is inhibited after the SAED modification. Optimized power conversion efficiency (PCE) of 17.8% is obtained through the enhanced light harvesting and reduced carrier recombination provided by SAED. More importantly, a solar energy storage effect due to the long‐persistent luminescence of SAED is obtained after light illumination is turned off. The introduction of downconverting material with long‐persistent luminescence in PSCs not only represents a new strategy to improve PCE and light stability by photoconversion from UV to visible light but also provides a new paradigm for solar energy storage.     

Mixed 3D–2D Passivation Treatment for Mixed‐Cation Lead Mixed‐Halide Perovskite Solar Cells for Higher Efficiency and Better Stability

Layered low‐dimensional perovskite structures employing bulky organic ammonium cations have shown significant improvement on stability but poorer performance generally compared to their 3D counterparts. Here, a mixed passivation (MP) treatment is reported that uses a mixture of bulky organic ammonium iodide (iso‐butylammonium iodide, iBAI) and formammidinium iodide (FAI), enhancing both power conversion efficiency and stability. Through a combination of inactivation of the interfacial trap sites, characterized by photoluminescence measurement, and formation of an interfacial energetic barrier by which ionic transport is reduced, demonstrated by Kelvin probe force microscopy, MP treatment of the perovskite/hole transport layer interface significantly suppresses photocurrent hysteresis. Using this MP treatment, the champion mixed‐halide perovskite cell achieves a reverse scan and stabilized power conversion efficiency of 21.7%. Without encapsulation, the devices show excellent moisture stability, sustaining over 87% of the original performance after 38 d storage in ambient environment under 75 ± 20% relative humidity. This work shows that FAI/ i BAI, is a new and promising material combination for passivating perovskite/selective‐contact interfaces.     

A Printable Organic Electron Transport Layer for Low‐Temperature‐Processed,Hysteresis‐Free,and Stable Planar Perovskite Solar Cells

Despite recent breakthroughs in power conversion efficiencies (PCEs), which have resulted in PCEs exceeding 22%, perovskite solar cells (PSCs) still face serious drawbacks in terms of their printability, reliability, and stability. The most efficient PSC architecture, which is based on titanium dioxide as an electron transport layer, requires an extremely high‐temperature sintering process (≈500 °C), reveals hysterical discrepancies in the device measurement, and suffers from performance degradation under light illumination. These drawbacks hamper the practical development of PSCs fabricated via a printing process on flexible plastic substrates. Herein, an innovative method to fabricate low‐temperature‐processed, hysteresis‐free, and stable PSCs with a large area up to 1 cm² is demonstrated using a versatile organic nanocomposite that combines an electron acceptor and a surface modifier. This nanocomposite forms an ideal, self‐organized electron transport layer (ETL) via a spontaneous vertical phase separation, which leads to hysteresis‐free, planar heterojunction PSCs with stabilized PCEs of over 18%. In addition, the organic nanocomposite concept is successfully applied to the printing process, resulting in a PCE of over 17% in PSCs with printed ETLs.     

MACl‐Assisted Ge Doping of Pb‐Hybrid Perovskite: A Universal Route to Stabilize High Performance Perovskite Solar Cells

Interfacial engineering, grain boundary, and surface passivation in organic–inorganic hybrid perovskite solar cells (HyPSCs) are effective in achieving high performance and enhanced durability. Organic additives and inorganic doping are generally used to chemically modify the surface contacting charge transport layers, and/or grain boundaries so as to reduce the defect density. Here, a simple but tricky one‐step method to dope organic–inorganic hybrid perovskite with Ge for the first time is reported. Unlike Ge doping to all‐inorganic perovskites, application of GeI₂ in organic–inorganic perovskite precursors is challenging due to the extremely poor solubility of GeI₂ in hybrid perovskite ink, leading to failure in the formation of uniform films. However, it is found that addition of methylammonium chloride (MACl) into the precursor remarkably increases the solubility of GeI₂. This MACl‐assisted Ge doping of hybrid perovskites produces high‐quality crystalline film with its surface passivated with nonvolatile GeI₂ (GeO₂) and the volatile MACl additive also improves the uniformity of GeO₂ distribution in the perovskite films. The resulting Ge‐doped mixed cation and mixed halide perovskite films with composition FA_0.83MA_0.17Ge_0.03Pb_0.97(I_0.9Br_0.1)₃ show superior photoluminescence lifetime, power conversion efficiency above 22%, and greater stability toward illumination and humidity, outperforming photovoltaic properties of HyPSCs prepared without the Ge doping.     

Improved Performance and Reliability of p‐i‐n Perovskite Solar Cells via Doped Metal Oxides

Perovskite photovoltaics (PVs) have attracted attention because of their excellent power conversion efficiency (PCE). Critical issues related to large‐area PV performance, reliability, and lifetime need to be addressed. Here, it is shown that doped metal oxides can provide ideal electron selectivity, improved reliability, and stability for perovskite PVs. This study reports p‐i‐n perovskite PVs with device areas ranging from 0.09 cm² to 0.5 cm² incorporating a thick aluminum‐doped zinc oxide (AZO) electron selective contact with hysteresis‐free PCE of over 13% and high fill factor values in the range of 80%. AZO provides suitable energy levels for carrier selectivity, neutralizes the presence of pinholes, and provides intimate interfaces. Devices using AZO exhibit an average PCE increase of over 20% compared with the devices without AZO and maintain the high PCE for the larger area devices reported. Furthermore, the device stability of p‐i‐n perovskite solar cells under the ISOS‐D‐1 is enhanced when AZO is used, and maintains 100% of the initial PCE for over 1000 h of exposure when AZO/Au is used as the top electrode. The results indicate the importance of doped metal oxides as carrier selective contacts to achieve reliable and high‐performance long‐lived large‐area perovskite solar cells.     

Vacuum‐Assisted Growth of Low‐Bandgap Thin Films (FA0.8MA0.2Sn0.5Pb0.5I3) for All‐Perovskite Tandem Solar Cells

All‐perovskite multijunction photovoltaics, combining a wide‐bandgap (WBG) perovskite top solar cell (E_G ≈1.6–1.8 eV) with a low‐bandgap (LBG) perovskite bottom solar cell (E_G < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum‐assisted growth control (VAGC) of solution‐processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well‐established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge‐carrier lifetime. The improved optoelectronic characteristics enable high‐performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four‐terminal all‐perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active‐area solar cells up to 1 cm².     

Diffraction‐Grated Perovskite Induced Highly Efficient Solar Cells through Nanophotonic Light Trapping

Achieving light harvesting is crucial for the efficiency of the solar cell. Constructing optical structures often can benefit from micro‐nanophotonic imprinting. Here, a simple and facile strategy is developed to introduce a large area grating structure into the perovskite‐active layer of a solar cell by utilizing commercial optical discs (CD‐R and DVD‐R) and achieve high photovoltaic performance. The constructed diffraction grating on the perovskite active layer realizes nanophotonic light trapping by diffraction and effectively suppresses carrier recombination. Compared to the pristine perovskite solar cells (PSCs), the diffraction‐grating perovskite devices with DVD obtain higher power conversion efficiency and photocurrent density, which are improved from 16.71% and 21.67 mA cm^?2 to 19.71% and 23.11 mA cm^?2. Moreover, the stability of the PSCs with diffraction‐grating‐structured perovskite active layer is greatly enhanced. The method can boost photonics merge into the remarkable perovskite materials for various applications.     

Lessons Learnt from Spatially Resolved Electro‐ and Photoluminescence Imaging: Interfacial Delamination in CH3NH3PbI3 Planar Perovskite Solar Cells upon Illumination

The influence of illumination on the long‐term performance of planar structured perovskite solar cells (PSCs) is investigated using fast and spatially resolved luminescence imaging. The authors analyze the effect of illuminated current density–voltage (J–V) and light‐soaking measurements on pristine PSCs by providing visual evidence for the spatial inhomogeneous evolution of device performance. Regions that are exposed to light initially produce stronger electroluminescence signals than surrounding unilluminated regions, mainly due to a lower contact resistance and, possibly, higher charge collection efficiency. Over a period of several days, however, these initially illuminated regions appear to degrade more quickly despite the device being stored in a dark, moisture‐ and oxygen‐free environment. Using transmission electron microscopy, this accelerated degradation is attributed to delamination between the perovskite and the titanium dioxide (TiO₂) layer. An ion migration mechanism is proposed for this delamination process, which is in accordance with previous current–voltage hysteresis observations. These results provide evidence for the intrinsic instability of CH₃NH₃PbI₃‐based devices under illumination and have major implications for the design of PSCs from the standpoint of long‐term performance and stability.     

Negligible‐Pb‐Waste and Upscalable Perovskite Deposition Technology for High‐Operational‐Stability Perovskite Solar Modules

An upscalable perovskite film deposition method combining raster ultrasonic spray coating and chemical vapor deposition is reported. This method overcomes the coating size limitation of the existing stationary spray, single‐pass spray, and spin‐coating methods. In contrast with the spin‐coating method (>90% Pb waste), negligible Pb waste during PbI₂ deposition makes this method more environmentally friendly. Outstanding film uniformity across the entire area of 5 cm × 5 cm is confirmed by both large‐area compatible characterization methods (electroluminescence and scattered light imaging) and local characterization methods (atomic force microscopy, scanning electron microscopy, photoluminescence mapping, UV–vis, and X‐ray diffraction measurements on multiple sample locations), resulting in low solar cell performance decrease upon increasing device area. With the FAPb(I_0.85Br_0.15)₃ (FA = formamidinium) perovskite layer deposited by this method, champion solar modules show a power conversion efficiency of 14.7% on an active area of 12.0 cm² and an outstanding shelf stability (only 3.6% relative power conversion efficiency decay after 3600 h aging). Under continuous operation (1 sun light illumination, maximum power point condition, dry N₂ atmosphere with <5% relative humidity, no encapsulation), the devices show high light‐soaking stability corresponding to an average T₈₀ lifetime of 535 h on the small‐area solar cells and 388 h on the solar module.     

Efficient Perovskite Photovoltaic‐Thermoelectric Hybrid Device

An efficient perovskite photovoltaic‐thermoelectric hybrid device is demonstrated by integrating the hole‐conductor‐free perovskite solar cell based on TiO₂/ZrO₂/carbon structure and the thermoelectric generator. The whole solar spectrum of AM 1.5 G is fully utilized with the ≈1.55 eV band gap perovskite (5‐AVA)_x(MA)_1?xPbI₃ absorbing the visible light and the carbon back contact absorbing the infrared light. The added thermoelectric generator improves the device performance by converting the thermal energy into electricity via the Seebeck effect. An optimized hybrid device is obtained with a maximum point power output of 20.3% and open‐circuit voltage of 1.29 V under the irradiation of 100 mW cm^?2.     

Correlating Phase Behavior with Photophysical Properties in Mixed‐Cation Mixed‐Halide Perovskite Thin Films

Mixed cation perovskites currently achieve very promising efficiency and operational stability when used as the active semiconductor in thin‐film photovoltaic devices. However, an in‐depth understanding of the structural and photophysical properties that drive this enhanced performance is still lacking. Here the prototypical mixed‐cation mixed‐halide perovskite (FAPbI₃)_0.85(MAPbBr₃)_0.15 is explored, and temperature‐dependent X‐ray diffraction measurements that are correlated with steady state and time‐resolved photoluminescence data are presented. The measurements indicate that this material adopts a pseudocubic perovskite α phase at room temperature, with a transition to a pseudotetragonal β phase occurring at ≈260 K. It is found that the temperature dependence of the radiative recombination rates correlates with temperature‐dependent changes in the structural configuration, and observed phase transitions also mark changes in the gradient of the optical bandgap. The work illustrates that temperature‐dependent changes in the perovskite crystal structure alter the charge carrier recombination processes and photoluminescence properties within such hybrid organic–inorganic materials. The findings have significant implications for photovoltaic performance at different operating temperatures, as well as providing new insight on the effect of alloying cations and halides on the phase behavior of hybrid perovskite materials.     

Four‐Terminal Perovskite/Silicon Multijunction Solar Modules

Multijunction solar cells employing perovskite and crystalline‐silicon (c‐Si) light absorbers bear the exciting potential to surpass the efficiency limit of market‐leading single‐junction c‐Si solar cells. However, scaling up this technology and maintaining high efficiency over large areas are challenging as evidenced by the small‐area perovskite/c‐Si multijunction solar cells reported so far. In this work, a scalable four‐terminal multijunction solar module design employing a 4 cm² semitransparent methylammonium lead triiodide perovskite solar module stacked on top of an interdigitated back contact c‐Si solar cell of identical area is demonstrated. With a combination of optimized transparent electrodes and efficient module design, the perovskite/c‐Si multijunction solar modules exhibit power conversion efficiencies of 22.6% on 0.13 cm² and 20.2% on 4 cm² aperture area. Furthermore, a detailed optoelectronic loss analysis along with strategies to enhance the performance is discussed.     

Molecular Engineering Using an Anthanthrone Dye for Low‐Cost Hole Transport Materials: A Strategy for Dopant‐Free,High‐Efficiency,and Stable Perovskite Solar Cells

In this report, highly efficient and humidity‐resistant perovskite solar cells (PSCs) using two new small molecule hole transporting materials (HTM) made from a cost‐effective precursor anthanthrone (ANT) dye, namely, 4,10‐bis(1,2‐dihydroacenaphthylen‐5‐yl)‐6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene (ACE‐ANT‐ACE) and 4,4′‐(6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene‐4,10‐diyl)bis(N,N‐bis(4‐methoxyphenyl)aniline) (TPA‐ANT‐TPA) are presented. The newly developed HTMs are systematically compared with the conventional 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methoxyphenylamino)‐9,9′‐spirbiuorene (Spiro‐OMeTAD). ACE‐ANT‐ACE and TPA‐ANT‐TPA are used as a dopant‐free HTM in mesoscopic TiO₂/CH₃NH₃PbI₃/HTM solid‐state PSCs, and the performance as well as stability are compared with Spiro‐OMeTAD‐based PSCs. After extensive optimization of the metal oxide scaffold and device processing conditions, dopant‐free novel TPA‐ANT‐TPA HTM‐based PSC devices achieve a maximum power conversion efficiency (PCE) of 17.5% with negligible hysteresis. An impressive current of 21 mA cm^?2 is also confirmed from photocurrent density with a higher fill factor of 0.79. The obtained PCE of 17.5% utilizing TPA‐ANT‐TPA is higher performance than the devices prepared using doped Spiro‐OMeTAD (16.8%) as hole transport layer at 1 sun condition. It is found that doping of LiTFSI salt increases hygroscopic characteristics in Spiro‐OMeTAD; this leads to the fast degradation of solar cells. While, solar cells prepared using undoped TPA‐ANT‐TPA show dewetting and improved stability. Additionally, the new HTMs form a fully homogeneous and completely covering thin film on the surface of the active light absorbing perovskite layers that acts as a protective coating for underlying perovskite films. This breakthrough paves the way for development of new inexpensive, more stable, and highly efficient ANT core based lower cost HTMs for cost‐effective, conventional, and printable PSCs.     

Surface Engineering of TiO2 ETL for Highly Efficient and Hysteresis‐Less Planar Perovskite Solar Cell (21.4%) with Enhanced Open‐Circuit Voltage and Stability

Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high‐performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO₂ (a‐SnO₂) between the TiO₂ ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double‐layer structure of TiO₂ compact layer (c‐TiO₂) and a‐SnO₂ ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a‐SnO₂/c‐TiO₂ ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c‐TiO₂ based device. Moreover, the modified device demonstrates a maximum open‐circuit voltage (V_oc) of 1.223 V with 387 mV loss in potential, which is among the highest reported value for PSCs with negligible hysteresis. The stability results show that the device on c‐TiO₂/a‐SnO₂ retains about 91% of its initial PCE value after 500 h light illumination, which is higher than pure c‐TiO₂ (67%) based devices. Interestingly, using a‐SnO₂/c‐TiO₂ ETL the PCE loss was only 10% of initial value under continuous UV light illumination after 30 h, which is higher than that of c‐TiO₂ based device (28% PCE loss).     

Fused‐Ring Electron Acceptor ITIC‐Th: A Novel Stabilizer for Halide Perovskite Precursor Solution

Solution‐processed perovskite solar cells have great potential for low‐cost roll‐to‐roll fabrication. However, the degradation of aged precursor solutions will become a critical obstacle to mass production. In this report, a small molecule (ITIC‐Th) is employed to stabilize the perovskite precursor solution containing mixed cations and halides. It is found that ITIC‐Th can effectively suppress the formation of yellow δ‐phase in the films made from aged precursor solutions. Consequently, the devices fabricated from the aged precursor solution with ITIC‐Th experience much less efficiency drop with the increase of the precursor aging time—from 19.20% (fresh) to 16.55% (39 d), compared with the devices made from conventional precursor solutions dropping from 18.07% (fresh) to 1.76% (39 d). The characterizations suggest that ITIC‐Th is beneficial for CH₃NH₃⁺ cations to be incorporated into the crystal structure, facilitating the formation of perovskite phase. Furthermore, the presence of ITIC‐Th in the perovskite thin film gives rise to additional photocurrent as well as improved fill factor due to the well‐matched energy levels, the passivation of defects, and the complementary absorption spectra, suggesting a new route toward future high‐efficiency solar cells—incorporating organic non‐fullerene acceptors and halide perovskite materials into the same active layer.