Ligang Yuan

Publication date: 16 October 2019

Source: Joule, Volume 3, Issue 10

Author(s): So-Min Yoo, Seog Joon Yoon, Juan A. Anta, Hyo Joong Lee, Pablo P. Boix, Iván Mora-Seró

Context & Scale

Summary

Graphical Abstract

Interface engineering is widely recognized as an effective strategy to improve the efficiency and stability of perovskite solar cells. This review is intended to provide a deep understanding of interface design principles for highly efficient and stable perovskite photovoltaic devices and a timely overview for state‐of‐the‐art interfacial materials in this rapidly developing field.

Exceptionally high efficiencies for organic–inorganic hybrid perovskite solar cells (PSCs) have been achieved. However, their operational stability still needs to be improved. The intrinsic instability of halide perovskites caused by the presence of volatile organic cations, as well as the degradation of hybrid perovskites induced by the adverse permeation of environmental water (H₂O)/oxygen (O₂) and the undesired ion diffusion or migration are the major reasons. Beyond strengthening perovskites themselves, interface engineering is now regarded as a valid strategy to prolong device lifetime by preventing the undesired degradation pathways. This comprehensive review highlights the utilization of practical interface engineering for enhancing the efficiency and stability of organic–inorganic lead halide PSCs. First, the impacts of interface design on the energy‐level alignment and carrier dynamics are overviewed. Second, recent progresses on the development of interfacial materials for simultaneously achieving high efficiency and stability of PSCs are summarized. At last, the interfacial layer design principles along with future outlook of this rapidly developing field are discussed.

The introduction of funtional molecular self‐assembled monolayers (SAMs) atop of zinc oxide (ZnO) effectively optimizes the energetic and heterojunction properties of the organic–metal oxide interface to improve the performance and photostability of nonfullerene polymer solar cells.

Abstract

Charge events across organic–metal oxide heterointerfaces routinely occur in organic electronics, yet strongly influence their overall performance and stability. They become even more complicated and challenging for the heterojunction conditions in polymer solar cells (PSCs), especially when nonfullerene acceptors with varied energetics are employed. In this work, an effective interfacial strategy that utilizes novel small molecule self‐assembled monolayers (SAMs) is developed to improve the electronic and electric, as well as chemical properties of organic–zinc oxide (ZnO) interfaces for nonfullerene PSCs. It is revealed that the tailored SAMs with well‐controlled energy levels and molecular dipoles can effectively optimize the energetic barrier and work function (WF) of heterointerface for optimal electron extraction. In addition, the introduction of SAMs atop of ZnO facilitates not only acceptor segregation near the n‐contact interface, but also passivation of the photocatalytic activities for ZnO, to improve overall performance and photo stability of the derived nonfullerene PSCs. Overall, the methodology and structure–property relationship revealed herein would be beneficial for a wide range of hybrid electronics.

To achieve efficient light emitting diodes, the solvent effects of in situ fabricated formamidinium‐lead‐iodide perovskite nanocrystals are investigated by monitoring the nucleation and growth process, and correlating the materials characterization. A modified LaMer model is proposed to describe the solvent effects of the on‐chip crystallization process, and a maximum external quantum efficiency up to 15.8% is achieved.

Abstract

The in situ fabricated perovskite nanocrystals (PNCs) obtained through spin‐coating a precursor solution are suitable candidates to achieve efficient perovskite light emitting diodes (PeLEDs). In this work, the solvent effects of on‐chip crystallization are investigated by correlating the nucleation and growth process of in situ fabricated formamidinium lead iodide (FAPbI₃) nanocrystals with their optical and electronic properties. The FAPbI₃ nanocrystals obtained from a precursor solution in γ‐butyrolactone (GBL) are smaller than those obtained from N,N‐dimethylformamide and dimethyl sulfoxide, and the relatively weak coordination between GBL and the precursor molecules enables reduced defect states in the resulted PNCs with enhanced photoluminescence properties. A modified LaMer model is proposed to describe the solvent effects in the on‐chip crystallization process. Based on these understandings, red emissive FA_0.87Cs_0.13PbI₃ nanocrystal films with absolute photoluminescence quantum yields up to 70% are realized. Finally, an efficient PeLED with maximum luminance of 218 cd m⁻² and peak external quantum efficiency of 15.8% is achieved with good reproducibility.

Nonconjugated multi‐zwitterionic small‐molecule electrolyte (NSE) molecules in perovskite solar cells (PSCs) act not only as both charge‐extracting layers for barrier‐free cathode charge collection but also as charged defect fillers in perovskite bulk and interfaces by spontaneous bottom‐up passivation. Thus, the NSE‐based PSCs deliver PCEs as high as 21.18% with an ultrahigh V _OC of 1.19 V, suppressed hysteresis, and enhanced stability.

Abstract

Recent perovskite solar cell (PSC) advances have pursued strategies for reducing interfacial energetic mismatches to mitigate energy losses, as well as to minimize interfacial and bulk defects and ion vacancies to maximize charge transfer. Here nonconjugated multi‐zwitterionic small‐molecule electrolytes (NSEs) are introduced, which act not only as charge‐extracting layers for barrier‐free charge collection at planar triple cation PSC cathodes but also passivate charged defects at the perovskite bulk/interface via a spontaneous bottom‐up passivation effect. Implementing these synergistic properties affords NSE‐based planar PSCs that deliver a remarkable power conversion efficiency of 21.18% with a maximum V _OC = 1.19 V, in combination with suppressed hysteresis and enhanced environmental, thermal, and light‐soaking stability. Thus, this work demonstrates that the bottom‐up, simultaneous interfacial and bulk trap passivation using NSE modifiers is a promising strategy to overcome outstanding issues impeding further PSC advances.

Highly efficient photoluminescence (PL‐QY = 68%), amplified spontaneous emission, and low‐threshold lasing in thin films of cesium lead bromide at room temperature are shown. Importantly, the films are not based on nanocrystals or quantum dots but consist of extended continuous layers, that are formed upon recrystallization of as‐deposited layers by thermal imprint.

Abstract

Cesium lead halide perovskites are of interest for light‐emitting diodes and lasers. So far, thin‐films of CsPbX₃ have typically afforded very low photoluminescence quantum yields (PL‐QY < 20%) and amplified spontaneous emission (ASE) only at cryogenic temperatures, as defect related nonradiative recombination dominated at room temperature (RT). There is a current belief that, for efficient light emission from lead halide perovskites at RT, the charge carriers/excitons need to be confined on the nanometer scale, like in CsPbX₃ nanoparticles (NPs). Here, thin films of cesium lead bromide, which show a high PL‐QY of 68% and low‐threshold ASE at RT, are presented. As‐deposited layers are recrystallized by thermal imprint, which results in continuous films (100% coverage of the substrate), composed of large crystals with micrometer lateral extension. Using these layers, the first cesium lead bromide thin‐film distributed feedback and vertical cavity surface emitting lasers with ultralow threshold at RT that do not rely on the use of NPs are demonstrated. It is foreseen that these results will have a broader impact beyond perovskite lasers and will advise a revision of the paradigm that efficient light emission from CsPbX₃ perovskites can only be achieved with NPs.

High efficiencies of 16.67% (certified as 16.0%) for rigid and 14.06% for flexible organic solar cells (OSCs) are achieved by employing a PM6:Y6:PC₇₁BM ternary system. This is a promising ternary heterojunction strategy for the development of highly efficient rigid and flexible OSCs.

Abstract

Ternary heterojunction strategies appear to be an efficient approach to improve the efficiency of organic solar cells (OSCs) through harvesting more sunlight. Ternary OSCs are fabricated by employing wide bandgap polymer donor (PM6), narrow bandgap nonfullerene acceptor (Y6), and PC₇₁BM as the third component to tune the light absorption and morphologies of the blend films. A record power conversion efficiency (PCE) of 16.67% (certified as 16.0%) on rigid substrate is achieved in an optimized PM6:Y6:PC₇₁BM blend ratio of 1:1:0.2. The introduction of PC₇₁BM endows the blend with enhanced absorption in the range of 300–500 nm and optimises interpenetrating morphologies to promote photogenerated charge dissociation and extraction. More importantly, a PCE of 14.06% for flexible ITO‐free ternary OSCs is obtained based on this ternary heterojunction system, which is the highest PCE reported for flexible state‐of‐the‐art OSCs. A very promising ternary heterojunction strategy to develop highly efficient rigid and flexible OSCs is presented.

Imaging and mapping characterization techniques are used to understand the fundamental properties that allow lead halide perovskites to have excellent performance metrics. In this work, commonly‐used and specialized tools that are used characterize halide perovskite materials and solar cells, including electron microscopy, atomic force microscopy, synchrotron‐based X‐ray mapping, and ultrafast and photoluminescence mapping are reviewed.

Abstract

Perovskite solar cells (PSCs) have attracted much attention as efficiencies have gone beyond 24%. To achieve these impressive numbers, the PSC scientific community is working to improve the perovskite optoelectronic properties. Imaging and mapping characterization techniques have been widely used to understand the fundamental properties that allow lead halide perovskites to achieve high performance. In this review, these techniques are evaluated, from simple tools, such as electron microscopy, to more complex systems that include atomic force microscopy, synchrotron‐based X‐ray mapping, and ultrafast and photoluminescence mapping. These tools have helped understand lead halide perovskites and their impressive optoelectronic properties, which make them outstanding materials for solar cell applications.

The side chain length of polymer donors can lead to miscibility differences. Shortening the side chains of polymer donors improves the device performance of fullerene‐based solar cells, but deteriorates the performance of small molecular and polymeric nonfullerene solar cells. Morphology investigations unveil that the miscibility between donor and acceptor in blend films depends on the side chain length of polymer donors.

Abstract

The development of nonfullerene acceptors has brought polymer solar cells into a new era. Maximizing the performance of nonfullerene solar cells needs appropriate polymer donors that match with the acceptors in both electrical and morphological properties. So far, the design rationales for polymer donors are mainly borrowed from fullerene‐based solar cells, which are not necessarily applicable to nonfullerene solar cells. In this work, the influence of side chain length of polymer donors based on a set of random terpolymers PTAZ‐TPD10‐Cn on the device performance of polymer solar cells is investigated with three different acceptor materials, i.e., a fullerene acceptor [70]PCBM, a polymer acceptor N2200, and a fused‐ring molecular acceptor ITIC. Shortening the side chains of polymer donors improves the device performance of [70]PCBM‐based devices, but deteriorates the N2200‐ and ITIC‐based devices. Morphology studies unveil that the miscibility between donor and acceptor in blend films depends on the side chain length of polymer donors. Upon shortening the side chains of the polymer donors, the miscibility between the donor and acceptor increases for the [70]PCBM‐based blends, but decreases for the N2200‐ and ITIC‐based blends. These findings provide new guidelines for the development of polymer donors to match with emerging nonfullerene acceptors.

Semi‐transparent perovskite solar cells (ST‐PSCs) have received great attention due to their promising applications in many areas, such as building integrated photovoltaics (BIPV), tandem devices, and wearable electronics. A general overview of recent advances in ST‐PSCs from materials and devices to applications is provided, and presented alongside some personal perspectives on their future development.

Abstract

Semitransparent solar cells (ST‐SCs) have received great attention due to their promising application in many areas, such as building integrated photovoltaics (BIPVs), tandem devices, and wearable electronics. In the past decade, perovskite solar cells (PSCs) have revolutionized the field of photovoltaics (PVs) with their high efficiencies and facile preparation processes. Due to their large absorption coefficient and bandgap tunability, perovskites offer new opportunities to ST‐SCs. Here, a general overview is provided on the recent advances in ST‐PSCs from materials and devices to applications and some personal perspectives on the future development of ST‐PSCs.

Lasing and loss dynamics of mechanically exfoliated, homologous 2D Ruddlesden–Popper perovskite (RPP, (C₄H₉NH₃)₂(CH₃NH₃) _{n −1}Pb _n I_{3 n +1}) crystals are reported. The Auger recombination and the electron–phonon coupling are the major loss channels, and they increase with the decreasing of inorganic layer thickness (n), leading to larger threshold in smaller‐n RPPs, and even the absence of lasing action for n < 3 above 78 K.

Abstract

2D Ruddlesden–Popper perovskites (RPPs) have aroused growing attention in light harvesting and emission applications owing to their high environmental stability. Recently, coherent light emission of RPPs was reported, however mostly from inhomologous thin films that involve cascade intercompositional energy transfer. Lasing and fundamental understanding of intrinsic laser dynamics in homologous RPPs free from intercompositional energy transfer is still inadequate. Herein, the lasing and loss mechanisms of homologous 2D (BA)₂(MA) _{n −1}Pb _n I_{3 n +1} RPP thin flakes mechanically exfoliated from the bulk crystal are reported. Multicolor lasing is achieved from the large‐n RPPs (n ≥ 3) in the spectral range of 620–680 nm but not from small‐n RPPs (n ≤ 2) even down to 78 K. With decreasing n, the lasing threshold increases significantly and the characteristic temperature decreases as 49, 25, and 20 K for n = 5, 4, and 3, respectively. The n‐engineered lasing behaviors are attributed to the stronger Auger recombination and exciton–phonon interaction as a result of the enhanced quantum confinement in the smaller‐n perovskites. These results not only advance the fundamental understanding of loss mechanisms in both inhomologous and homologous RPP lasers but also provide insights into developing low‐threshold, substrate‐free, and multicolor 2D semiconductor microlasers.

The full‐color photoluminescence emissions (457–650 nm) of g‐C₃N₄ are first achieved by simple one‐step molecular doping, especially the red‐light emission feature. The corresponding multiple‐color LED devices and the white LED with high color quality are experimentally fabricated with theoretical demonstration of their potential commercial value.

Abstract

Polymeric g‐C₃N₄ with controllable photoluminescence emission wavelength in the whole visible light range (450–650 nm) is synthesized through the one‐step molecular doping during the thermal condensation process of g‐C₃N₄ conjugated framework, which opens up its application beyond the conventional catalysis scopes. By adjusting the doped content of hetero‐molecules, the modified g‐C₃N₄ with the optical properties controlled according to the demand of practical applications can be facilely and largely obtained. It overcomes the limitation of the narrow adjusting range of conventional g‐C₃N₄ on optical properties and makes it become more promising for applications in solid‐state displays. The corresponding multiple‐color g‐C₃N₄‐based LED devices and the white‐light LEDs with high quality can be obtained as supported by experiments and theoretical calculations. Moreover, the effect of doped molecule on the π‐conjugated system of g‐C₃N₄ is systematically studied here, and the tunable luminescence mechanism is proposed.

Publication date: 21 August 2019

Source: Joule, Volume 3, Issue 8

Author(s): Hyun Suk Jung, Gill Sang Han, Nam-Gyu Park, Min Jae Ko

Context & Scale

In article no. 1900125, Guokun Ma, Hao Wang, and co‐workers use liquid crystal (LC) molecule (4'‐heptyl‐4‐biphenylcarbonitrile) as a binding agent to connect the grain boundaries of perovskites. After treatment with the LC, perovskite crystal growth orientation can be controlled and the electron transport process is accelerated. Remarkably, the LC greatly contributes to the environmental stability of the devices.

In article no. 1900087, Jian‐Qiang Liu, Xiao‐Tao Hao, and co‐workers introduce polypropylene into a bulk heterojunction consisting of donors and acceptors to fabricate effective organic solar cells with a thick active layer. The incorporation of polypropylene improves the crystallinity of the donor and reduces the aggregation size of the acceptor, which facilitates exciton dissociation and charge transition and inhibits the recombination of carriers.

In article no. 1900192, Ai Ping Chen, Shuang Yang, Yu Hou, and co‐workers employ a versatile alkaline earth metals doping strategy to engineer the electronic structure of NiO_x contacts for inverted planar perovskite solar cells, in which the champion device demonstrates a power conversion efficiency of 19.49% with a high open circuit voltage of 1.14 V. Alkaline earth metals doping can significantly optimize the electrical properties by deepening the valence band maximum and enhancing the hole conductivity.

A temperature‐tuned antisolvent bathing method is introduced for fabricating highly oriented and large‐grain perovskite thin films. Using large‐area compatible cold antisolvent bathing, a high‐quality perovskite film is obtained with a reduced defect density and an enhanced charge‐carrier extraction capability, which achieves a champion power‐conversion efficiency of 18.50%.

Abstract

Scaling large‐area solar cells is in high demand for the commercialization of perovskite solar cells (PSCs) with a high power‐conversion efficiency (PCE). However, few roll‐to‐roll‐compatible deposition methods for the formation of highly oriented uniform perovskite films are reported. Herein, a facile cold antisolvent bathing approach compatible with large‐area fabrication is introduced. The wet precursor films are submerged in a cold antisolvent bath at 0 °C, and the retarded nucleation and growth kinetics allow highly oriented perovskite to be grown along the [110] and [220] directions, perpendicular to the substrate. The high degree of the preferred crystal orientation benefits the effective charge extraction and reduces the amount of inter‐ and intra‐grain defects inside the perovskite films, improving the PCE from 16.48% (ambient‐bathed solar cell) to 18.50% (cold‐bathed counterpart). The cold antisolvent bathing method is employed for the fabrication of large‐area (8 × 10 cm²) PSCs with uniform photovoltaic device parameters, thereby verifying the scale‐up capability of the method.

Highly efficient photoluminescence (PL‐QY = 68%), amplified spontaneous emission, and low‐threshold lasing in thin films of cesium lead bromide at room temperature are shown. Importantly, the films are not based on nanocrystals or quantum dots but consist of extended continuous layers that are formed upon recrystallization of as‐deposited layers by thermal imprint.

Abstract

Cesium lead halide perovskites are of interest for light‐emitting diodes and lasers. So far, thin‐films of CsPbX₃ have typically afforded very low photoluminescence quantum yields (PL‐QY < 20%) and amplified spontaneous emission (ASE) only at cryogenic temperatures, as defect related nonradiative recombination dominated at room temperature (RT). There is a current belief that, for efficient light emission from lead halide perovskites at RT, the charge carriers/excitons need to be confined on the nanometer scale, like in CsPbX₃ nanoparticles (NPs). Here, thin films of cesium lead bromide, which show a high PL‐QY of 68% and low‐threshold ASE at RT, are presented. As‐deposited layers are recrystallized by thermal imprint, which results in continuous films (100% coverage of the substrate), composed of large crystals with micrometer lateral extension. Using these layers, the first cesium lead bromide thin‐film distributed feedback and vertical cavity surface emitting lasers with ultralow threshold at RT that do not rely on the use of NPs are demonstrated. It is foreseen that these results will have a broader impact beyond perovskite lasers and will advise a revision of the paradigm that efficient light emission from CsPbX₃ perovskites can only be achieved with NPs.

A multifunctional chemical linker of 4‐imidazoleacetic acid hydrochloride (ImAcHCl) between SnO₂ and a perovskite layer improves the average power conversion efficiency from 18.60% to 20.22% due to the upward shift of band position, reduced nonradiative recombination, and improved carrier lifetime. In addition, interfacial engineering improves thermal and moisture stability.

Abstract

Chemical interaction at a heterojunction interface induced by an appropriate chemical linker is of crucial importance for high efficiency, hysteresis‐less, and stable perovskite solar cells (PSCs). Effective interface engineering in PSCs is reported via a multifunctional chemical linker of 4‐imidazoleacetic acid hydrochloride (ImAcHCl) that can provide a chemical bridge between SnO₂ and perovskite through an ester bond with SnO₂ via esterification reaction and an electrostatic interaction with perovskite via imidazolium cation in ImAcHCl and iodide anion in perovskite. In addition, the chloride anion in ImAcHCl plays a role in the improvement of crystallinity of perovskite film crystallinity. The introduction of ImAcHCl onto SnO₂ realigns the positions of the conduction and valence bands upwards, reduces nonradiative recombination, and improves carrier life time. As a consequence, average power conversion efficiency (PCE) is increased from 18.60% ± 0.50% to 20.22% ± 0.34% before and after surface modification, respectively, which mainly results from an enhanced voltage from 1.084 ± 0.012 V to 1.143 ± 0.009 V. The best PCE of 21% is achieved by 0.1 mg mL⁻¹ ImAcHCl treatment, along with negligible hysteresis. Moreover, an unencapsulated device with ImAcHCl‐modified SnO₂ shows much better thermal and moisture stability than unmodified SnO₂.

Nonconjugated multi‐zwitterionic small‐molecule electrolyte (NSE) molecules in perovskite solar cells (PSCs) act not only as both charge‐extracting layers for barrier‐free cathode charge collection but also as charged defect fillers in perovskite bulk and interfaces by spontaneous bottom‐up passivation. Thus, the NSE‐based PSCs deliver PCEs as high as 21.18% with an ultrahigh V _OC of 1.19 V, suppressed hysteresis, and enhanced stability.

Abstract

Recent perovskite solar cell (PSC) advances have pursued strategies for reducing interfacial energetic mismatches to mitigate energy losses, as well as to minimize interfacial and bulk defects and ion vacancies to maximize charge transfer. Here nonconjugated multi‐zwitterionic small‐molecule electrolytes (NSEs) are introduced, which act not only as charge‐extracting layers for barrier‐free charge collection at planar triple cation PSC cathodes but also passivate charged defects at the perovskite bulk/interface via a spontaneous bottom‐up passivation effect. Implementing these synergistic properties affords NSE‐based planar PSCs that deliver a remarkable power conversion efficiency of 21.18% with a maximum V _OC = 1.19 V, in combination with suppressed hysteresis and enhanced environmental, thermal, and light‐soaking stability. Thus, this work demonstrates that the bottom‐up, simultaneous interfacial and bulk trap passivation using NSE modifiers is a promising strategy to overcome outstanding issues impeding further PSC advances.

The introduction of funtional molecular self‐assembled monolayers (SAMs) atop of zinc oxide (ZnO) effectively optimizes the energetic and heterojunction properties of the organic–metal oxide interface to improve the performance and photostability of nonfullerene polymer solar cells.

Abstract

Charge events across organic–metal oxide heterointerfaces routinely occur in organic electronics, yet strongly influence their overall performance and stability. They become even more complicated and challenging for the heterojunction conditions in polymer solar cells (PSCs), especially when nonfullerene acceptors with varied energetics are employed. In this work, an effective interfacial strategy that utilizes novel small molecule self‐assembled monolayers (SAMs) is developed to improve the electronic and electric, as well as chemical properties of organic–zinc oxide (ZnO) interfaces for nonfullerene PSCs. It is revealed that the tailored SAMs with well‐controlled energy levels and molecular dipoles can effectively optimize the energetic barrier and work function (WF) of heterointerface for optimal electron extraction. In addition, the introduction of SAMs atop of ZnO facilitates not only acceptor segregation near the n‐contact interface, but also passivation of the photocatalytic activities for ZnO, to improve overall performance and photo stability of the derived nonfullerene PSCs. Overall, the methodology and structure–property relationship revealed herein would be beneficial for a wide range of hybrid electronics.

Temperature‐dependent X‐ray diffraction, absorption and photoluminescence measurements on methylammonium lead iodide thin films with grain sizes ranging from the micrometer to the tens of nanometer scale reveal that the low‐temperature phase transition is increasingly suppressed with decreasing grain size. These results unveil the remarkable sensitivity of optoelectronic and structural properties to the local environment in perovskite thin films.

Abstract

Grain size in polycrystalline halide perovskite films is known to have an impact on the optoelectronic properties of the films, but its influence on their soft structural properties and phase transitions is unclear. Here, temperature‐dependent X‐ray diffraction, absorption, and macro‐ and micro‐photoluminescence measurements are used to investigate the tetragonal to orthorhombic phase transition in thin methylammonium lead iodide films with grain sizes ranging from the micrometer scale down to the tens of nanometer scale. It is shown that the phase transition nominally at ≈150 K is increasingly suppressed with decreasing grain size and, in the smallest grains, the first evidence of a phase transition is only seen at temperatures as low as ≈80 K. With decreasing grain size, an increasing magnitude of the hysteresis is also seen in the structural and optoelectronic properties when cooling to, and then upon heating from, 100 K. This work reveals the remarkable sensitivity of the optoelectronic, physical, and phase properties to the local environment of the perovskite structure, which will have large ramifications for phase and defect engineering in operating devices.

A high power conversion efficiency of 13.5% achieved with single‐junction ternary polymer solar cells based on PTB7‐Th, PC₇₁BM, and COi8DFIC is fabricated by slot‐die coating. This work extends to the fabrication of large‐area modules, and also to roll‐to‐roll fabrication, and demonstrates the strong potential of the slot‐die coated ternary system for commercial applications.

Abstract

The record efficiency of the state‐of‐the‐art polymer solar cells (PSCs) is rapidly increasing, due to the discovery of high‐performance photoactive donor and acceptor materials. However, strong questions remain as to whether such high‐efficiency PSCs can be produced by scalable processes. This paper reports a high power conversion efficiency (PCE) of 13.5% achieved with single‐junction ternary PSCs based on PTB7‐Th, PC₇₁BM, and COi8DFIC fabricated by slot‐die coating, which shows the highest PCE ever reported in PSCs fabricated by a scalable process. To understand the origin of the high performance of the slot‐die coated device, slot‐die coated photoactive films and devices are systematically investigated. These results indicate that the good performance of the slot‐die PSCs can be due to a favorable molecule‐structure and film‐morphology change by introducing 1,8‐diiodooctane and heat treatment, which can lead to improved charge transport with reduced carrier recombination. The optimized condition is then used for the fabrication of large‐area modules and also for roll‐to‐roll fabrication. The slot‐die coated module with 30 cm² active‐area and roll‐to‐roll produced flexible PSC has shown 8.6% and 9.6%, respectively. These efficiencies are the highest in each category and demonstrate the strong potential of the slot‐die coated ternary system for commercial applications.