[1] M Graetzel, R A J Janssen, D B Mitzi et al. Materials interface engineering for solution-processed photovoltaics. Nature, 488, 304(2012).

[2] W Chen, Y Wu, Y Yue et al. Efficient and stable large-area perovskite solar cells with inorganic charge extraction layers. Science, 350, 944(2015).

[3] H Chen, F Ye, W T Tang et al. A solvent- and vacuum-free route to large-area perovskite films for efficient solar modules. Nature, 550, 92(2017).

[4] H Tan, A Jain, O Voznyy et al. Efficient and stable solution-processed planar perovskite solar cells via contact passivation. Science, 355, 722(2017).

[5] A Kojima, K Teshima, Y Shirai et al. Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J Am Chem Soc, 131, 6050(2009).

[6] L G Wang, H P Zhou, J N Hu et al. A Eu³⁺-Eu²⁺ ion redox shuttle imparts operational durability to Pb-I perovskite solar cells. Science, 363, 265(2019).

[7] Q Jiang, Y Zhao, X W Zhang et al. Surface passivation of perovskite film for efficient solar cells. Nat Photonics, 13, 460(2019).

[8] E H Jung, N J Jeon, E Y Park et al. Efficient, stable and scalable perovskite solar cells using poly(3-hexylthiophene). Nature, 567, 511(2019).

[9] D Weber. CH₃NH₃SnBr_xI_3–x (x = 0–3), a Sn(II)-system with cubic perovskite structure. Zeitschrift Fur Naturforschung B, 33, 862(2014).

[10] Weber D. CH₃NH₃PBX₃, a Pb(II)-system with cubic perovskite structure. Zeitschrift Fur Naturforschung B, 33, 1443(2014).

[11] M Kim, G H Kim, T K Lee et al. Methylammonium chloride induces intermediate phase stabilization for efficient perovskite solar cells. Joule, 3, 2179(2019).

[12] J Burschka, N Pellet, S J Moon et al. Sequential deposition as a route to high-performance perovskite-sensitized solar cells. Nature, 499, 316(2013).

[13] H Zhou, Q Chen, G Li et al. Interface engineering of highly efficient perovskite solar cells. Science, 345, 542(2014).

[14] W S Yang, B W Park, E H Jung et al. Iodide management in formamidinium-lead-halide-based perovskite layers for efficient solar cells. Science, 356, 1376(2017).

[15] N J Jeon, J H Noh, W S Yang et al. Compositional engineering of perovskite materials for high-performance solar cells. Nature, 517, 476(2015).

[16] W S Yang, J H Noh, N J Jeon et al. High-performance photovoltaic perovskite layers fabricated through intramolecular exchange. Science, 348, 1234(2015).

[17] L K Yang, Q Xiong, Y B Li et al. Artemisinin-passivated mixed-cation perovskite films for durable flexible perovskite solar cells with over 21% efficiency. J Mater Chem A, 9, 1574(2021).

[18] M H Kumar, N Yantara, S Dharani et al. Flexible, low-temperature, solution processed ZnO-based perovskite solid state solar cells. Chem Commun (Camb), 49, 11089(2013).

[19] C Roldán-Carmona, O Malinkiewicz, A Soriano et al. Flexible high efficiency perovskite solar cells. Energy Environ Sci, 7, 994(2014).

[20] S S Shin, W S Yang, J H Noh et al. High-performance flexible perovskite solar cells exploiting Zn₂SnO₄ prepared in solution below 100 °C. Nat Commun, 6, 7410(2015).

[21] D Yang, R X Yang, X D Ren et al. Hysteresis-suppressed high-efficiency flexible perovskite solar cells using solid-state ionic-liquids for effective electron transport. Adv Mater, 28, 5206(2016).

[22] J Yoon, H Sung, G Lee et al. Superflexible, high-efficiency perovskite solar cells utilizing graphene electrodes: Towards future foldable power sources. Energy Environ Sci, 10, 337(2017).

[23] J S Feng, X J Zhu, Z Yang et al. Record efficiency stable flexible perovskite solar cell using effective additive assistant strategy. Adv Mater, 30, 1801418(2018).

[24] K Q Huang, Y Y Peng, Y X Gao et al. High-performance flexible perovskite solar cells via precise control of electron transport layer. Adv Energy Mater, 9, 1901419(2019).

[25] X C Meng, Z R Cai, Y Y Zhang et al. Bio-inspired vertebral design for scalable and flexible perovskite solar cells. Nat Commun, 11, 3016(2020).

[26] Q S Dong, M Chen, Y H Liu et al. Flexible perovskite solar cells with simultaneously improved efficiency, operational stability, and mechanical reliability. Joule, 5, 1587(2021).

[27] M Li, Y G Yang, Z K Wang et al. Perovskite grains embraced in a soft fullerene network make highly efficient flexible solar cells with superior mechanical stability. Adv Mater, 31, 1901519(2019).

[28] V Zardetto, T M Brown, A Reale et al. Substrates for flexible electronics: A practical investigation on the electrical, film flexibility, optical, temperature, and solvent resistance properties. J Polym Sci B, 49, 638(2011).

[29] M Lee, Y Jo, D S Kim et al. Flexible organo-metal halide perovskite solar cells on a Ti metal substrate. J Mater Chem A, 3, 4129(2015).

[30] M Lee, Y Ko, Y Jun. Efficient fiber-shaped perovskite photovoltaics using silver nanowires as top electrode. J Mater Chem A, 3, 19310(2015).

[31] M Lee, Y Ko, B K Min et al. Silver nanowire top electrodes in flexible perovskite solar cells using titanium metal as substrate. ChemSusChem, 9, 31(2016).

[32] J Troughton, D Bryant, K Wojciechowski et al. Highly efficient, flexible, indium-free perovskite solar cells employing metallic substrates. J Mater Chem A, 3, 9141(2015).

[33] G S Han, S Lee, M L Duff et al. Highly bendable flexible perovskite solar cells on a nanoscale surface oxide layer of titanium metal plates. ACS Appl Mater Interfaces, 10, 4697(2018).

[34] Y M Xiao, G Y Han, H H Zhou et al. An efficient titanium foil based perovskite solar cell: Using a titanium dioxide nanowire array anode and transparent poly(3, 4-ethylenedioxythiophene) electrode. RSC Adv, 6, 2778(2016).

[35] B Abdollahi Nejand, P Nazari, S Gharibzadeh et al. All-inorganic large-area low-cost and durable flexible perovskite solar cells using copper foil as a substrate. Chem Commun Camb Engl, 53, 747(2017).

[36] M M Tavakoli, K H Tsui, Q Zhang et al. Highly efficient flexible perovskite solar cells with antireflection and self-cleaning nanostructures. ACS Nano, 9, 10287(2015).

[37] X Z Dai, Y H Deng, C H van Brackle et al. Scalable fabrication of efficient perovskite solar modules on flexible glass substrates. Adv Energy Mater, 10, 1903108(2020).

[38] B Dou, E M Miller, J A Christians et al. High-performance flexible perovskite solar cells on ultrathin glass: Implications of the TCO. J Phys Chem Lett, 8, 4960(2017).

[39] K Mahmood, S Sarwar, M T Mehran. Current status of electron transport layers in perovskite solar cells: Materials and properties. RSC Adv, 7, 17044(2017).

[40] D Y Liu, T L Kelly. Perovskite solar cells with a planar heterojunction structure prepared using room-temperature solution processing techniques. Nat Photonics, 8, 133(2014).

[41] T Y Jin, W Li, Y Q Li et al. High-performance flexible perovskite solar cells enabled by low-temperature ALD-assisted surface passivation. Adv Opt Mater, 6, 1801153(2018).

[42] L J Zuo, Z W Gu, T Ye et al. Enhanced photovoltaic performance of CH₃NH₃PbI₃ perovskite solar cells through interfacial engineering using self-assembling monolayer. J Am Chem Soc, 137, 2674(2015).

[43] R Azmi, C L Lee, I H Jung et al. Simultaneous improvement in efficiency and stability of low-temperature-processed perovskite solar cells by interfacial control. Adv Energy Mater, 8, 1702934(2018).

[44] R Azmi, W T Hadmojo, S Sinaga et al. High-efficiency low-temperature ZnO based perovskite solar cells based on highly polar, nonwetting self-assembled molecular layers. Adv Energy Mater, 8, 1701683(2018).

[45] J X Song, L J Liu, X F Wang et al. Highly efficient and stable low-temperature processed ZnO solar cells with triple cation perovskite absorber. J Mater Chem A, 5, 13439(2017).

[46] X K Huang, J Yang, S Mao et al. Controllable synthesis of hollow Si anode for long-cycle-life lithium-ion batteries. Adv Mater, 26, 4326(2014).

[47] J L Yang, B D Siempelkamp, E Mosconi et al. Origin of the thermal instability in CH₃NH₃PbI₃ thin films deposited on ZnO. Chem Mater, 27, 4229(2015).

[48] P Docampo, J M Ball, M Darwich et al. Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates. Nat Commun, 4, 2761(2013).

[49] D Yang, R X Yang, J Zhang et al. High efficiency flexible perovskite solar cells using superior low temperature TiO₂. Energy Environ Sci, 8, 3208(2015).

[50] Giacomo F Di, V Zardetto, A D'Epifanio et al. Flexible perovskite photovoltaic modules and solar cells based on atomic layer deposited compact layers and UV-irradiated TiO₂ scaffolds on plastic substrates. Adv Energy Mater, 5, 1401808(2015).

[51] I Jeong, H Jung, M Park et al. A tailored TiO₂ electron selective layer for high-performance flexible perovskite solar cells via low temperature UV process. Nano Energy, 28, 380(2016).

[52] Y Dkhissi, F Z Huang, S Rubanov et al. Low temperature processing of flexible planar perovskite solar cells with efficiency over 10%. J Power Sources, 278, 325(2015).

[53] N Ahn, K Kwak, M S Jang et al. Trapped charge-driven degradation of perovskite solar cells. Nat Commun, 7, 1(2016).

[54] P Qin, S Tanaka, S Ito et al. Inorganic hole conductor-based lead halide perovskite solar cells with 12.4% conversion efficiency. Nat Commun, 5, 3834(2014).

[55] B Wu, K W Fu, N Yantara et al. Charge accumulation and hysteresis in perovskite-based solar cells: An electro-optical analysis. Adv Energy Mater, 5, 1500829(2015).

[56] B J Kim, M C Kim, D G Lee et al. Interface design of hybrid electron extraction layer for relieving hysteresis and retarding charge recombination in perovskite solar cells. Adv Mater Interfaces, 5, 1800993(2018).

[57] C L Wang, D W Zhao, C R Grice et al. Low-temperature plasma-enhanced atomic layer deposition of tin oxide electron selective layers for highly efficient planar perovskite solar cells. J Mater Chem A, 4, 12080(2016).

[58] Q Jiang, L Q Zhang, H L Wang et al. Enhanced electron extraction using SnO₂ for high-efficiency planar-structure HC(NH₂)₂PbI₃-based perovskite solar cells. Nat Energy, 2, 16177(2017).

[59] M Park, J Y Kim, H J Son et al. Low-temperature solution-processed Li-doped SnO₂ as an effective electron transporting layer for high-performance flexible and wearable perovskite solar cells. Nano Energy, 26, 208(2016).

[60] C L Wang, L Guan, D W Zhao et al. Water vapor treatment of low-temperature deposited SnO₂ electron selective layers for efficient flexible perovskite solar cells. ACS Energy Lett, 2, 2118(2017).

[61] S S Shin, W S Yang, E J Yeom et al. Tailoring of electron-collecting oxide nanoparticulate layer for flexible perovskite solar cells. J Phys Chem Lett, 7, 1845(2016).

[62] J Ha, H Kim, H Lee et al. Device architecture for efficient, low-hysteresis flexible perovskite solar cells: Replacing TiO₂ with C60 assisted by polyethylenimine ethoxylated interfacial layers. Sol Energy Mater Sol Cells, 161, 338(2017).

[63] J Chung, S S Shin, K Hwang et al. Record-efficiency flexible perovskite solar cell and module enabled by a porous-planar structure as an electron transport layer. Energy Environ Sci, 13, 4854(2020).

[64] X Yin, P Chen, M Que et al. Highly efficient flexible perovskite solar cells using solution-derived NiO_x hole contacts. ACS Nano, 10, 3630(2016).

[65] H Zhang, J Q Cheng, F Lin et al. Pinhole-free and surface-nanostructured NiO_x film by room-temperature solution process for high-performance flexible perovskite solar cells with good stability and reproducibility. ACS Nano, 10, 1503(2016).

[66] J W Jo, M S Seo, M Park et al. Improving performance and stability of flexible planar-heterojunction perovskite solar cells using polymeric hole-transport material. Adv Funct Mater, 26, 4464(2016).

[67] W M Qiu, U W Paetzold, R Gehlhaar et al. An electron beam evaporated TiO₂layer for high efficiency planar perovskite solar cells on flexible polyethylene terephthalate substrates. J Mater Chem A, 3, 22824(2015).

[68] C Bi, B Chen, H T Wei et al. Efficient flexible solar cell based on composition-tailored hybrid perovskite. Adv Mater, 29, 1605900(2017).

[69] M D Xiao, F Z Huang, W C Huang et al. A fast deposition-crystallization procedure for highly efficient lead iodide perovskite thin-film solar cells. Angew Chem, 126, 10056(2014).

[70] N J Jeon, J H Noh, Y C Kim et al. Solvent engineering for high-performance inorganic–organic hybrid perovskite solar cells. Nat Mater, 13, 897(2014).

[71] Z B Yang, C C Chueh, F Zuo et al. High-performance fully printable perovskite solar cells via blade-coating technique under the ambient condition. Adv Energy Mater, 5, 1500328(2015).

[72] Z Wang, L X Zeng, C L Zhang et al. Rational interface design and morphology control for blade-coating efficient flexible perovskite solar cells with a record fill factor of 81%. Adv Funct Mater, 30, 2001240(2020).

[73] C Chen, C Wu, X D Ding et al. Constructing binary electron transport layer with cascade energy level alignment for efficient CsPbI₂Br solar cells. Nano Energy, 71, 104604(2020).

[74] D Luo, W Yang, Z Wang et al. Enhanced photovoltage for inverted planar heterojunction perovskite solar cells. Science, 360, 1442(2018).

[75] J Xi, K Xi, A Sadhanala et al. Chemical sintering reduced grain boundary defects for stable planar perovskite solar cells. Nano Energy, 56, 741(2019).

[76] M Z Liu, M B Johnston, H J Snaith. Efficient planar heterojunction perovskite solar cells by vapour deposition. Nature, 501, 395(2013).

[77] T Lei, F H Li, X Y Zhu et al. Flexible perovskite solar modules with functional layers fully vacuum deposited. Sol RRL, 4, 2000292(2020).

[78] Y Y Kim, T Y Yang, R Suhonen et al. Roll-to-roll gravure-printed flexible perovskite solar cells using eco-friendly antisolvent bathing with wide processing window. Nat Commun, 11, 5146(2020).

[79] Z C Yang, W J Zhang, S H Wu et al. Slot-die coating large-area formamidinium-cesium perovskite film for efficient and stable parallel solar module. Sci Adv, 7, eabg3749(2021).

[80] S Razza, S Castro-Hermosa, A Di Carlo et al. Research Update: Large-area deposition, coating, printing, and processing techniques for the upscaling of perovskite solar cell technology. APL Mater, 4, 091508(2016).

[81] C T Zuo, D Vak, D C Angmo et al. One-step roll-to-roll air processed high efficiency perovskite solar cells. Nano Energy, 46, 185(2018).

[82] Q D Tai, X Y Guo, G Q Tang et al. Antioxidant grain passivation for air-stable tin-based perovskite solar cells. Angew Chem Int Ed, 58, 806(2019).

[83] X C Meng, Z Xing, X T Hu et al. Stretchable perovskite solar cells with recoverable performance. Angew Chem Int Ed, 59, 16602(2020).

[84] B J Kim, D H Kim, Y Y Lee et al. Highly efficient and bending durable perovskite solar cells: Toward a wearable power source. Energy Environ Sci, 8, 916(2015).

[85] F Louwet, L Groenendaal, J Dhaen et al. PEDOT/PSS: Synthesis, characterization, properties and applications. Synth Met, 135/136, 115(2003).

[86] J Huang, P F Miller, J C de Mello et al. Influence of thermal treatment on the conductivity and morphology of PEDOT/PSS films. Synth Met, 139, 569(2003).

[87] M Kaltenbrunner, G Adam, E D Głowacki et al. Flexible high power-per-weight perovskite solar cells with chromium oxide–metal contacts for improved stability in air. Nat Mater, 14, 1032(2015).

[88] J Han, S Yuan, L N Liu et al. Fully indium-free flexible Ag nanowires/ZnO:F composite transparent conductive electrodes with high haze. J Mater Chem A, 3, 5375(2015).

[89] H Lu, J Sun, H Zhang et al. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells. Nanoscale, 8, 5946(2016).

[90] K K Sears, M Fievez, M Gao et al. ITO-free flexible perovskite solar cells based on roll-to-roll, slot-Die coated silver nanowire electrodes. Sol RRL, 1, 1700059(2017).

[91] Y W Li, L Meng, Y Yang et al. High-efficiency robust perovskite solar cells on ultrathin flexible substrates. Nat Commun, 7, 10214(2016).

[92] H Bian, D L Bai, Z W Jin et al. Graded bandgap CsPbI_2+xBr_1−x perovskite solar cells with a stabilized efficiency of 14.4%. Joule, 2, 1500(2018).

[93] Z Li, S A Kulkarni, P P Boix et al. Laminated carbon nanotube networks for metal electrode-free efficient perovskite solar cells. ACS Nano, 8, 6797(2014).

[94] X Y Wang, Z Li, W J Xu et al. TiO₂ nanotube arrays based flexible perovskite solar cells with transparent carbon nanotube electrode. Nano Energy, 11, 728(2015).

[95] I Jeon, T Chiba, C Delacou et al. Single-walled carbon nanotube film as electrode in indium-free planar heterojunction perovskite solar cells: Investigation of electron-blocking layers and dopants. Nano Lett, 15, 6665(2015).

[96] Q Luo, H Ma, F Hao et al. Carbon nanotube based inverted flexible perovskite solar cells with all-inorganic charge contacts. Adv Funct Mater, 27, 1703068(2017).

[97] J Deng, L B Qiu, X Lu et al. Elastic perovskite solar cells. J Mater Chem A, 3, 21070(2015).

[98] S Ameen, M S Akhtar, H K Seo et al. An insight into atmospheric plasma jet modified ZnO quantum dots thin film for flexible perovskite solar cell: Optoelectronic transient and charge trapping studies. J Phys Chem C, 119, 10379(2015).

[99] Z K Liu, P You, C Xie et al. Ultrathin and flexible perovskite solar cells with graphene transparent electrodes. Nano Energy, 28, 151(2016).

[100] Q Luo, H Ma, Q Hou et al. All-carbon-electrode-based endurable flexible perovskite solar cells. Adv Funct Mater, 28, 1706777(2018).

[101] Q X Fu, X L Tang, B Huang et al. Recent progress on the long-term stability of perovskite solar cells. Adv Sci, 5, 1700387(2018).

[102] F Matteocci, L Cinà, E Lamanna et al. Encapsulation for long-term stability enhancement of perovskite solar cells. Nano Energy, 30, 162(2016).

[103] G S Han, J S Yoo, F D Yu et al. Highly stable perovskite solar cells in humid and hot environment. J Mater Chem A, 5, 14733(2017).

[104] J S Yoo, G S Han, S Lee et al. Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments. Nano Res, 10, 3885(2017).