Sang Hyuk Im

• PhD
• Professor (Associate) at Kyung Hee University

Perovskite solar cells have been of great interest over the past decade, reaching a remarkable power conversion efficiency of 26.7%, which is comparable to best performing silicon devices. Moreover, the capability of perovskite solar cells to be solution-processed at low cost makes them an ideal candidate for future photovoltaic systems that could...

A novel approach to enhancing the efficiency and long‐term stability of perovskite solar cells (PSCs) is presented through strategic interfacial modification using bespoke graphene quantum dots (GQDs). GQDs with controlled alkylamine chain lengths, such as butylamine (C4), octylamine (C8), and dodecylamine (C12), were customized to have the proper...

A novel methodology has been devised to fabricate pristine δ-formamidinium lead triiodide (δ-FAPbI3) single crystals, crucial for highly efficient and stable perovskite solar cells (PSCs). This approach involves a liquid-phase reaction between FAI and PbI2 in N,N-dimethylformamide, succeeded by antisolvent crystallization with acetonitrile, ensurin...

Perovskites are gaining attention as next-generation materials across various fields due to their exceptional physical, electrical, and optical properties. Perovskite light-emitting diodes (PeLEDs), in particular, have achieved external quantum efficiencies (EQE) exceeding 30% with ongoing enhancements. However, inorganic PeLEDs, despite their dura...

Tin‐halide perovskite solar cells (THPSCs), while offering low toxicity and high theoretical power conversion efficiency, suffer from inferior device performance compared to lead‐based counterparts. The primary limitations arise from challenges in fabricating high‐quality perovskite films and mitigating the oxidation of Sn²⁺ ions, which leads to se...

Stability and oxidation are major bottlenecks in improving the performance of Sn‐based perovskite solar cells. In this study, we present the formation of an n‐type Cs2SnI6 double‐perovskite (Sn‐DP) layer on a (PEAI)0.15(FAI)0.85SnI2 perovskite (Sn‐P) layer using an orthogonal solution‐processable spray‐coating method. This novel approach achieves a...

Poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), the most widely used hole injection layer (HIL) for perovskite light‐emitting diodes (PeLEDs), has a large hole injection energy barrier and easy charge separation at PEDOT:PSS/perovskite layer. Here, a self‐assembling molecule (SAM) called (2‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)ethyl)...

The rapid success achieved from perovskite solar cell has drawn great expectations for commercialization of next-generation photovoltaics. Among the various perovskite materials, the inorganic perovskite derivatives have been of particular interest, ascribed to its superior thermal and chemical stability, which is a crucial criterion for reliable l...

This study aims to enhance the performance of inorganic perovskite light‐emitting diodes (PeLEDs) by incorporating porous silica (p‐SiO2) to fabricate perovskite‐composite films for electroluminescence (EL) devices. This is because, in addition to the inorganic perovskite material, composites with inherently stable materials are needed for perovski...

Interfacial modulation is crucial for optimizing charge carrier management and thwarting undesired ion-metal diffusion in perovskite photovoltaics. This study highlights a groundbreaking approach, employing semiconducting perylene-diimide (PDINN) as a cathode interlayer (CIL) in an inverted tin halide perovskite solar cell (THPSC). PDINN imparts th...

Pure δ‐formamidinium lead triiodide (δ‐FAPbI3) single crystal for highly efficient perovskite solar cell (PCS) with long‐term stability is prepared by a new method consisting of liquid phase reaction of FAI and PbI2 in N,N‐dimethyl formamide and antisolvent crystallization using acetonitrile. In this method, the incorporation of any impurity into t...

Despite the optoelectronic similarities between tin and lead halide perovskites, the performance of tin‐based perovskite solar cells remains far behind, with the highest reported efficiency to date being ≈14%. This is highly correlated to the instability of tin halide perovskite, as well as the rapid crystallization behavior in perovskite film form...

Although inorganic CsPbI2Br perovskite has an ideal bandgap for indoor photovoltaics (IPVs), its poor solubility causes rapid crystallization during spin‐coating process and deteriorates the performance of IPVs. Here, efficient CsPbI2Br IPVs are demonstrated through slower crystallization by introduction of dimethylammonium iodide (DMAI), which has...

Tin‐Based Perovskite In article number 2200631, Ki‐Ha Hong, Sang Hyuk Im, Chang Eun Song, and co‐workers reported Br incorporation enhanced the vertical orientation of 2D/3D tin‐based perovskite, leading to an improved efficiency of 10.12% with high stability. Furthermore, it is expected that tin‐based perovskite will replace lead and be applicable...

Perovskite Solar Cells In article number 2200573, Jin Hyuck Heo, Won‐Sik Han, Sang Hyuk Im, and co‐workers synthesized a novel electron accepting material, PDI‐Cb, by introducing diphenyl‐o‐carboranyl groups at the bay positions of the perylene diimide (PDI) unit. The inverted perovskite solar cells with PDI‐Cb interlayer demonstrate 22.31% power c...

TiO2 has been widely adopted as an electron transport layer during the fabrication of efficient metal halide perovskite solar cells (MHP‐SCs). In this study, we prepared acetylacetone (Acac)‐modulated TiO2 nanoparticles (NPs) suitable for low‐temperature solution processing via the sol‐gel method. Acac coordinates with TiO2 NPs and preferably passi...

Tin‐halide perovskite solar cells (THPSCs) are attractive in the photovoltaic field as a promising candiate to address the issue of potential lead toxicity and to approach the theoretical efficiency limit in lead‐halide perovskite photovoltaics. Nevertheless, THPSCs suffer from fast crystallization, low defect tolerance, mismatched energy levels as...

To investigate the synergistic effect of perylene diimide (PDI) unit and diphenyl‐o‐carboranyl (Cb) group, the PDI‐Cb with Cb groups at the bay positions of the PDI unit is synthesized. As introducing 3‐dimensional carboranyl group into the bay position, PDI–Cb showed distorted geometry between PDI core and adjacent phenyl ring of Cb due to the rin...

All-inorganic CsPbI3 perovskite has a near-ideal band gap, high thermal stability, and simple material composition, thus presenting a promising option for developing perovskite/Si tandem solar cells. However, CsPbI3 undergoes a rapid phase transition under exposure to moisture and exhibits a significant performance gap relative to other perovskite...

Large area and efficient CsPbBr3 perovskite light emitting diodes (PeLEDs) were demonstrated by readily commercializable spray-coating method. The PeLEDs with controlled crystal grain size exhibited maximum electroluminescence peak position of ~534 nm, emission spectrum of ~18 nm of full width at half maximum, maximum luminance of 20388 cd/m², maxi...

The tin-halide perovskite solar cells (THPSCs) have immensly attracted the photovoltaic researchers because of the intriguing quality to replace the toxic lead and to approach the theoretical efficiency limit in halide perovskite photovoltaics. In spite of this, THPSCs suffer from the fast crystallization, low defect tolerance, mismatched energy le...

Flexible Photovoltaic Devices In article number 2100733, Sang Hyuk Im and co-workers developed super flexible transparent conducting oxide (TCO)-free perovskite solar cells with a single-layered graphene electrode on polydimethylsiloxane substrates with excellent bending stability. By co-doping the graphene/PTAA layers with varying concentrations o...

Highly efficient organic-inorganic hybrid perovskite solar cells (OIHP-SCs) are often fabricated on a transparent conducting oxide (TCO) substrate such as indium tin oxide (ITO). However, the presence of TCOs are disadvantageous to the development of flexible OIHP-SCs due to the brittle nature of ITO, easily breakable during bending. In this report...

Formamidinium lead triiodide (FAPbI3) with stable black perovskite phase and without significantly changing its bandgap is demonstrated by the incorporation of CaCl2. More incorporated CaCl2 in FAPbI3 creates a desirable crystal structure, satisfying the Goldschmidt tolerance factor, and thereby stabilizing black perovskite phase under ambient cond...

Perovskite materials have demonstrated superior performance in many aspects of optoelectronic applications including X-ray scintillation, photovoltaic, photodetection and so on. In this work, we demonstrate a self-powered flexible all-perovskite X-ray detector with high sensitivity and fast response, which can be realized by integrating CsPbBr3 per...

Graphene quantum dots (GQDs) synthesized by single phase solution chemistry are embedded in metal halide perovskite (MHP) films because they can act as passivating defects that are present throughout the MHP film, not only at the interface but also throughout the bulk of the film. The perovskite photodetectors composed of indium-doped tin oxide/SnO...

We report fabrication of low-density polymeric microparticles (micropolymofoam particles [μPFPs]) using the piezoelectric inkjet method. After ejecting a polymer solution prepared by dissolving polymers in a volatile organic solvent, microdroplets are periodically generated through an inkjet nozzle in the air. Rapid evaporation of the solvent as it...

Enhancement in weak-light detection and other photodetection properties was observed for organic-inorganic halide perovskite photodetectors as a result of benzylammonium iodide (BzAI) treatment at the methylammonium lead triiodide (MAPbI3) and hole-transport layer (HTL) interface. After treatment, growth of the two-dimensional Ruddlesden-Popper per...

Developing intrinsically self-healable semiconducting polymers is particularly important for realizing stretchable electronic devices which can spontaneously recover their mechanical damage. We synthesized a series of conjugated donor polymers (PTO2-tm series) functionalized with a thymine group at the terminal of the side chain. Bulk heterojunctio...

Waterproof light‐emitting perovskite–polymer composite microparticles are synthesized by a continuous one‐step microfluidic reactor, which enables in situ production of metal halide perovskite nanoparticles (MHP‐NPs) by the ligand‐assisted reprecipitation process (LARP) and the encapsulation of MHP‐NPs by UV cross‐linking polymerization in the micr...

Morphology and crystal grain size of inorganic CsPbBr3 metal halide perovskite (MHP) films are controllable through a diffusion-controlled anti-solvent dripping crystallization method using an anti-solvent mixture of toluene (Tol):isopropanol (IPA). The 8:2 (v:v) Tol:IPA anti-solvent enables the production of a pinhole-free CsPbBr3 MHP film with th...

Inorganic perovskite solar cells (PSCs) are promising for achieving long-term operational stability with good device performance. Here, we report the fabrication of inorganic CsPbI 2Br-based perovskite thin films with a well-defined CsPbI 3−xBr x composition gradient in the surface region by a scalable, orthogonal processable spray-coating approach...

Post-processable CH3NH3PbX3 (MAPbX3, X = Cl, Br, I, and their mixtures) metal halide perovskite nanocrystals (MHP NCs) for thin solid-film were synthesized by modified ligand-assisted re-precipitation method adopting MAPbX3, N,N-dimethylformamide (DMF), toluene, and oleic acid and hexylamine as MHP, good solvent, poor solvent, and co-ligands, respe...

Sn‐based halide perovskites are the most promising alternatives for developing Pb‐free perovskite solar cell materials. However, the stability of Sn halide perovskites is the biggest concern for future developments. The phase stability and the doping‐level control should be resolved for Sn perovskites to compete with Pb‐based analogs. Herein, inter...

A void-free metal halide perovskite (MHP) layer on a mesoscopic TiO2 (m-TiO2) film was formed via the wetting-induced infiltration of MHP solution in the m-TiO2 film via a green ultrasonic spray coating process using a non-hazardous solvent. The systematic investigation of the behavior of ultrasonic-sprayed MHP micro-drops on the m-TiO2 film disclo...

Although many synthetic methods such as hot injection and anionic exchange can produce full-color perovskite nanocrystals (PNCs), their emission spectra are broadened by compositional non-uniformity. Here, we propose the synthetic method, hydrogen halide (HX; X = Cl, Br, and I)-mediated uniform halide anion exchange at mild temperatures, for high c...

Structure engineering of trivalent metal halide perovskites (MHPs) such as A3Sb2X9 (A = a monovalent cation such as methyl ammonium (MA), cesium (Cs), and formamidinium (FA) and X = a halogen such as I, Br, and Cl) is of great interest because a two dimensional (2D) layer structure with direct bandgap has narrower bandgap energy than a zero dimensi...

The cesium lead tri-iodide (CsPbI3) perovskite is a promising candidate for stable light absorbers and red-light emitting sources due to its outstanding stability. Phase engineering is the most important approach for the commercialization of CsPbI3 because the optically inactive nonperovskite structure is more stable than 3-dimensional (3-D) perovs...

Understanding the effects of the chemical structures of donor polymers on the photovoltaic properties of their corresponding organic photovoltaic (OPV) devices under various light-intensity conditions is important for improving the performance of these devices. We synthesized a series of copolymers based on poly[(2,6-(4,8-bis(5-(2-thioethylhexyl)th...

In article number 1905951, Jong H. Kim, Sang Hyuk Im, O‐Pil Kwon, and co‐workers report a series of electron transporting homochiral and heterochiral stereoisomers of naphthalene diimide crystalline materials and show simultaneous achievement of low‐temperature solution processability, high device performance, and long‐term temporal device stabilit...

A series of chiral stereoisomers of electron transporting materials with two chiral substituents is rationally designed and synthesized, and the influence of stereoisomerism on their physical and electronic properties is investigated to demonstrate highly efficient and stable perovskite solar cells (PSCs). Compared to mesomeric naphthalene diimide...

The data provided in this data set is the study of organic-inorganic hybrid perovskite solar cells fabricated through incorporating the small amounts of ammonium halide NH4X (X = F, Cl, Br, I) additives into a CH3NH3PbI3 (MAPbI3) perovskite solution and is published as "High-Performance CH3NH3PbI3 Inverted Planar Perovskite Solar Cells via Ammonium...

Highly efficient and thermally stable inorganic CsPbI2Br mesoscopic metal halide perovskite (MHP) solar cells with a poly-3-hexylthiophene (P3HT) hole transporting layer (HTL) are demonstrated by spin-washing of the P3HT HTL since the light harvesting efficiency is improved by minimizing the co-absorption of light by P3HT, and the open-circuit volt...

We synthesized a donor polymer of bis(2-ethylhexyl)thiophene-substituted benzodithiophene (BDT-Th) and 1,3-bis(2-ethylhexyl)-5,7-di(thiophene-2-yl)benzo[1,2-c:4,5-c′]dithiophene-4,8-dione, for which the BDT-Th unit includes chlorine and sulfur-bridged 2-ethylhexyl in the thiophene side group. When compared with PBDB-TF, which includes fluorine and...

Uniform Ag nanocubes are reproducibly synthesized by a AgCl particle‐mediated heterogeneous nucleation and disassembly process in polyol chemistry. By introducing N,N‐dimethylformamide (DMF) in a conventional polyol method with HCl etchant, Ag nanocrystals (NCs) begin to be nucleated on the surface of AgCl‐precipitated particles due to the promoted...

Organic-inorganic hybrid perovskites have recently attracted substantial attention as a top candidate for use as light-absorbing materials in high-efficiency, low-cost and solution-processable photovoltaic devices owing to their excellent optoelectronic properties. Here, we fabricated inverted planar perovskite solar cells by incorporating small am...

High performance and hysteresis-less mesoscopic CsPbI2Br perovskite solar cells (PSCs) are demonstrated by adapting hole transporting materials (HTMs) with controlled highest occupied molecular orbital (HOMO) values. The used model HTMs are poly-3-hexylthiophene (P3HT), poly-triarylamine (P-TAA), poly-fluoren-8-triarylamine (PF8-TAA), and poly-inde...

PbS/CuS hetero-nanostructured (HNS) quantum dots(QDs) with finely controlled PbS core-size (˜3, ˜5, and ˜7 nm) and CuS content (4, 7, 11, 14, 17, and 45 mol%) were successfully synthesized via the suppressed cationic exchange reaction rate by reducing the reaction temperature down to −3 °C. By the precise synthesis of the PbS/CuS HNS QDs, we found...

Perovskite solar cells (PSCs) have attracted a great deal of attention due to their combined advantages of high efficiency and good flexibility. Here, we addressed the latest technology and future prospects of flexible hybrid PSCs. The fleixble PSCs are composed to flexible stubstrate, transparent electrode, electron (or hole) conductor, perovskite...

Highly efficient (17.3%, aperture area = 1 cm²) and stable semitransparent CH(NH2)2PbI3‐xBrx (FAPbI3‐xBrx) perovskite solar cells (PSCs) are demonstrated by lamination process through conductive poly[(2,5‐bis(2‐hexyldecyloxy)phenylene)‐alt‐(5,6‐difluoro‐4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]‐thiadiazole)] doped with nonhygroscopic tris(pentafluorophe...

The Cover Feature shows the homochiral asymmetric‐shaped electron transporting materials (ETMs) exhibiting excellent film‐forming ability with high solubility in various organic solvents. The homochiral ETM‐based inverted perovskite solar cells exhibit very high power conversion efficiency with high reproducibility. Introducing homochiral asymmetri...

A design strategy is proposed for electron‐transporting materials (ETMs) with homochiral asymmetric‐shaped groups for highly efficient non‐fullerene perovskite solar cells (PSCs). The electron transporting N,N′‐bis[(R)‐1‐phenylethyl]naphthalene‐1,4,5,8‐tetracarboxylic diimide (NDI‐PhE) consists of two asymmetric‐shaped chiral (R)‐1‐phenylethyl (PhE...

Invited for this month′s cover is the collaborative team of the groups of O‐Pil Kwon and Jong H. Kim at Ajou University and Sang Hyuk Im at Korea University. The image shows non‐fullerene organic electron transporting materials for perovskite solar cells. The Concept itself is available at 10.1002/cssc.201801908. “ETMs are very attractive for PSCs…...

The Front Cover shows high‐performance perovskite solar cells (PSCs) based on non‐fullerene organic electron transporting materials (ETMs). Organic ETMs are very attractive for high‐performance PSCs due to their efficient electron transporting characteristics and low‐temperature solution processability. In their Concept, S.‐K. Jung, D. S. Lee et al...

Preserving the stability of Sn-based halide perovskites is a primary concern in developing photovoltaic light-absorbing materials for lead-free perovskite solar cells. While the addition of SnX2 (X=F, Cl, Br) has been demonstrated to improve the photovoltaic performance of Sn halide perovskite solar cells, the mechanistic roles of SnX2 in the perfo...

Organic electron transporting materials (ETMs) with low‐temperature solution processability and high electron transfer/transport characteristics have received significant attention for their use in high performance perovskite solar cells (PSCs). In contrast to widely investigated fullerene‐based organic ETMs for PSCs, only few types of non‐fulleren...

Flexible Ti metal substrate-based efficient planar type CH3NH3PbI3 (MAPbI3) organic-inorganic hybrid perovskite solar cells are fabricated by lamination of the flexible Ti metal substrate/dense TiO2 electron transporting layer formed by anodization reaction/MAPbI3/polytriarylamine (PTAA) and the graphene/polydimethylsiloxane (PDMS) transparent elec...

Readily commercializable and cost‐effective next‐generation CsPbBr3 perovskite nanocrystals (PNCs) based X‐ray detectors are demonstrated. The PNCs‐based X‐ray detector exhibits higher spatial resolution (9.8 lp mm⁻¹ at modulation transfer function (MTF) = 0.2 and 12.5–8.9 lp mm⁻¹ for a linear line chart), faster response time (≈200 ns), and compar...

Double perovskites using dual metal cations are promising candidates for Pb-free perovskites. This study shows that the electronic structures of double perovskites (A2B⁺B³⁺X6) can be significantly modulated by cation ordering changes. The bandgap of Cs2AgBiCl6 can be affected by changing octahedron alignments, and even zero gap states can be realiz...

In article number 1800295, Sang‐Wook Kim and co‐workers report highly stable perovskite nanocrystals with cesium and rubidium. Their stability under UV and heat results from an increased defect‐formation resistance and exciton binding energy with Rb⁺ incorporation. This work helps mitigate the biggest weakness of perovskite structures and, thus, in...

A new non‐fullerene electron transporting material based on naphthalene diimide with indane groups having simultaneous alicyclic and aromatic characteristics is developed by Sang Hyuk Im, Jong H. Kim, O‐Pil Kwon, and co‐workers in article number 1800346. Low‐temperature solution‐processable perovskite solar cells using this material show up to 20.2...

Mixed‐cation CsxRb1–xPbX3 (X = Cl, Br, I) perovskite quantum dots (PeQDs) are developed and show high quantum yields of 93% and 86% for green and blue wavelengths, respectively. The stability is significantly improved under heat, UV, and water aging conditions. These improved properties are explained by the increased defect formation resistance and...

Super-flexible bis(trifluoromethanesulfonyl)-amide (TFSA)-doped graphene transparent conducting electrode (GR TCE)-based FAPbI3-xBrx perovskite solar cells with 18.9 % power conversion efficiency (PCE) for rigid device and 18.3 % for flexible one are demonstrated because the TFSA-doped GR TCE reveals high conductivity and high transmittance. The un...

The crystal grain size of CH3NH3PbI3 (MAPbI3) organic-inorganic hybrid perovskite (OHP) film was controllable in the range from ~60 nm to ~600 nm by non-solvents inter-diffusion controlled crystallization process in dripping crystallization method for the formation of perovskite film. The MAPbI3 OHP non-volatile resistive random access memory with...

A face-on oriented and p-doped semi-crystalline conjugated polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]-thiadiazole)] (PPDT2FBT) was studied as a hole-transport layer (HTL) in methylammonium lead triiodide (MAPbI3)-based perovskite solar cells (PVSCs). PPDT2FBT exhibits a mid-band gap (1.7...

High performance solid-state PbS quantum dot-sensitized solar cells (QD-SSCs) with stable 9.2 % power conversion efficiency at 1 Sun condition are demonstrated by introduction of hybrid perovskite inter-layer. The PbS QDs formed on mesoscopic TiO¬¬2 (mp-TiO2) by spin-assisted successive precipitation and anionic exchange reaction method do not exhi...

Recently, hybrid perovskite solar cells have attracted great interest because they can be fabricated to low cost, flexible, and highly efficient solar cells. Here, we introduced recent advances of flexible hybrid perovskite solar cells. We introduced research background of flexible perovskite solar cells in introduction part. Then we composed the m...

In perovskite solar cells (PSCs), overlying hole transporting materials (HTMs) are important for achieving high efficiencies and as well as protecting perovskite active layers from degradation factors. This study reports synthesis of dopant-free HTM based on a D′-A-D-A-D-A-D′ (D, D′: electron donor, A: electron acceptor) conjugated structure and in...

Super flexible TCO-free FAPbI3-xBrx planar type inverted perovskite solar cells with 17.9 % power conversion efficiency at 1 Sun condition were demonstrated by introducing APTES (3-aminopropyl triethoxysilane) adhesion promoter between PET flexible substrate and AuCl3-doped single-layer graphene transparent electrode (TCE). Due to the formation of...

10% semi-transparent neutral color sandwich type CH3NH3PbI3 (MAPbI3) perovskite sub-module (active area = 25 cm²) with UV cross-linked polystyrene passivation layer showed ∼2.8% degradation of initial efficiency after continuous light soaking of 1 Sun for 1000 h at 55 °C. Due to the role of island-morphology-MAPbI3 as selective UV-cut mask, the UV...

Colloidal metal-halide perovskite quantum dots (QDs) with a dimension < exciton Bohr diameter DB (quantum size regime) emerged as promising light emitters due to their spectrally-narrow light, facile color tuning and high photoluminescence quantum efficiency (PLQE). However, their size-sensitive emission wavelength and color purity, and low electro...

We employed AuCl3-doped graphene as a p-type transparent conducting electrode (TCE) in an p-i-n type CH3NH3PbI3 perovskite solar cell using poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) and phenyl-C61-butyric acid methyl ester as the hole and electron transporting layers, respectively, and obtained 17.4-17.9% power conversion efficiency...

Highly efficient CH3NH3PbI3 based inverted planar perovskite solar cells (PeSCs) are accomplished by incorporating the poly([N,N’-bis(2-octyldodecyl)-1,4,5,8-naphthalene bis(dicarboximide)-2,6-diyl]-alt-5,5’-(2,2’-bithiophene)) (PNDI-2T) as polymeric n-type electron conductor in the phenyl-C61-butyric acid methyl ester (PCBM) electron conductor and...

We devised a straightforward spin-assisted successive precipitation and anion exchange reaction (spin-SPAER) process in order to deposit relatively uniform PbS quantum dots (QDs) on mesoporous TiO2 (mp-TiO2). For the spin-SPAER process, we used PbX2 (X = I, Br, and Cl) precursors instead of a Pb(NO3)2 precursor and consequently deposited individual...

Inverted-type CH3NH3PbI3 flexible perovskite solar cells (FPeSCs) with improved flexibility were prepared by incorporating a polymeric electron conductor, poly([N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalene bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)) (PNDI-2T), into small-molecule electron conductor phenyl-C61-butyric acid methyl ester...