S. Moghadamzadeh, I. M. Hossain, M. Jakoby, B. A. Nejand, D. Rueda-Delgado, J. A. Schwenzer, S. Gharibzadeh, T. Abzieher, M. R. Khan and A. A. Haghighirad, "Spontaneous enhancement of the stable power conversion efficiency in perovskite solar cells," Journal of Materials Chemistry A, 8, 670-682, 2020.
 L. Zhou, Z. Lin, Z. Ning, T. Li, X. Guo, J. Ma, J. Su, C. Zhang, J. Zhang and S. Liu, "Highly efficient and stable planar perovskite solar cells with modulated diffusion passivation toward high power conversion efficiency and ultrahigh fill factor," Solar RRL, 3, 1900293, 2019.
 J.-P. Correa-Baena, A. Abate, M. Saliba, W. Tress, T. J. Jacobsson, M. Grätzel, and A. Hagfeldt, "The rapid evolution of highly efficient perovskite solar cells," Energy & Environmental Science, 10, 710-727, 2017.
 Z. Safari, M. B. Zarandi, and M. R. Nateghi, "Improved environmental stability of HTM free perovskite solar cells by a modified deposition route," Chemical Papers, 73, 2667-2678, 2019.
 F. Sahli, J. Werner, B. A. Kamino, M. Bräuninger, R. Monnard, B. Paviet-Salomon, L. Barraud, L. Ding, J. J. D. Leon and D. Sacchetto, "Fully textured monolithic perovskite/silicon tandem solar cells with 25.2% power conversion efficiency,"Nature materials, 17, 820-826, 2018.
 M. Kim, I. w. Choi, S. J. Choi, J. W. Song, S.-I. Mo, J.-H. An, Y. Jo, S. Ahn, S. K. Ahn and G.-H. Kim, "Enhanced electrical properties of Li-salts doped mesoporous TiO2 in perovskite solar cells," Joule, 5, 659-672, 2021.
 X. Liu, J. Jiang, F. Wang, Y. Xiao, I. D. Sharp and Y. Li, "High photovoltage inverted planar heterojunction perovskite solar cells with all-inorganic selective contact layers," ACS applied materials & interfaces, 11, 46894-46901, 2019.
 H. Mohseni, M. Dehghanipour, N. Dehghan, F. Tamaddon, M. Ahmadi, M. Sabet, and A. Behjat, "Enhancement of the photovoltaic performance and the stability of perovskite solar cells via the modification of electron transport layers with reduced graphene oxide/polyaniline composite," Solar Energy, 213, 59-66, 2021.
 K. Yao, F. Li, Q. He, X. Wang, Y. Jiang, H. Huang, and A. K.-Y. Jen, "A copper-doped nickel oxide bilayer for enhancing efficiency and stability of hysteresis-free inverted mesoporous perovskite solar cells," Nano Energy, 40, 155-162, 2017.
 H. Zhou, Q. Chen, G. Li, S. Luo, T.-b. Song, H.-S. Duan, Z. Hong, J. You, Y. Liu, and Y. Yang, "Interface engineering of highly efficient perovskite solar cells," Science, 345, 542-546, 2014.
 X. Li, W. Ye, X. Zhou, F. Huang, and D. Zhong, "Increased efficiency for perovskite photovoltaics based on aluminum-doped zinc oxide transparent electrodes via surface modification," The Journal of Physical Chemistry C, 121, 10282-10288, 2017.
 J. Peng, T. Duong, X. Zhou, H. Shen, Y. Wu, H. K. Mulmudi, Y. Wan, D. Zhong, J. Li, and T. Tsuzuki, "Efficient indium‐doped TiOx electron transport layers for high‐performance perovskite solar cells and perovskite‐silicon tandems," Advanced Energy Materials, 7, 1601768, 2017.
 H. Tan, A. Jain, O. Voznyy, X. Lan, F. P. G. De Arquer, J. Z. Fan, R. Quintero-Bermudez, M. Yuan, B. Zhang, and Y. Zhao, "Efficient and stable solution-processed planar perovskite solar cells via contact passivation," Science, 355, 722-726, 2017.
 Y. Miao, P. Du, Z. Wang, Q. Chen, and M. Eslamian, "Ultrasonic vibration imposed on nanoparticle-based ZnO film improves the performance of the ensuing perovskite solar cell," Materials Research Express, 5, 026404, 2018.
 W. S. Yang, B.-W. Park, E. H. Jung, N. J. Jeon, Y. C. Kim, D. U. Lee, S. S. Shin, J. Seo, E. K. Kim, and J. H. Noh, "Iodide management in formamidinium-lead-halide–based perovskite layers for efficient solar cells," Science, 356, 1376-1379, 2017.
 L. Chen, H. Cao, S. Wang, Y. Luo, T. Tao, J. Sun, and M. Zhang, "Efficient air-stable perovskite solar cells with a (FAI) ₀. ₄₆ (MAI) ₀. ₄₀ (MABr) ₀. ₁₄ (PbI₂) ₀. ₈₆ (PbBr₂) ₀. ₁₄ active layer fabricated via a vacuum flash-assisted method under RH> 50%," RSC advances, 2019.
 M. Zhang, W. Zhou, W. Hu, B. Li, Q. Qiao and S. Yang, "Modifying mesoporous TiO2 by ammonium sulfonate boosts performance of perovskite solar cells," ACS applied materials & interfaces, 12, 12696-12705, 2020.
 W. Ye, J. Xiang, F. Huang, and D. Zhong, "Towards large-area perovskite solar cells: the influence of compact and mesoporous TiO2 electron transport layers," Materials Research Express, 5, 085506, 2018.
 R. D. Chavan, P. Yadav, A. Nimbalkar, S. P. Bhoite, P. N. Bhosale, and C. K. Hong, "Ruthenium doped mesoporous titanium dioxide for highly efficient, hysteresis-free and stable perovskite solar cells," Solar Energy, 186, 156-165, 2019.
 M. Yu, H. Sun, X. Huang, Y. Yan and W. Zhang, "In situ-formed and low-temperature-deposited Nb:TiO2 compact-mesoporous layer for hysteresis-less perovskite solar cells with high performance," Nanoscale research letters, 15, 1-8, 2020.
 Y. Tamaki, K. Hara, R. Katoh, M. Tachiya, and A. Furube, "Femtosecond visible-to-IR spectroscopy of TiO2 nanocrystalline films: elucidation of the electron mobility before deep trapping," The Journal of Physical Chemistry C, 113, 11741-11746, 2009.
 Q. Zhang, V. n. Celorrio, K. Bradley, F. Eisner, D. Cherns, W. Yan, and D. J. Fermín, "Density of deep trap states in oriented TiO2 nanotube arrays," The Journal of Physical Chemistry C, 118, 18207-18213, 2014.
 S. K. Pathak, A. Abate, P. Ruckdeschel, B. Roose, K. C. Gödel, Y. Vaynzof, A. Santhala, S. I. Watanabe, D. J. Hollman, and N. Noel, "Performance and stability enhancement of dye‐sensitized and perovskite solar cells by Al doping of TiO2," Advanced Functional Materials, 24, 6046-6055, 2014.
 B. Roose, K. C. Gödel, S. Pathak, A. Sadhanala, J. P. C. Baena, B. D. Wilts, H. J. Snaith, U. Wiesner, M. Grätzel, and U. Steiner, "Enhanced efficiency and stability of perovskite solar cells through Nd‐doping of mesostructured TiO2," Advanced Energy Materials, 6, 1501868, 2016.
 M. Li, Y. Zhao, L. Zhu, J. Song and Y. Qiang, "Performance enhancement of perovskite solar cells via Nb/Ta-doped TiO2 mesoporous layers " Journal of Materials Science: Materials in Electronics, 30, 9038-9044, 2019.
 M. Afzali, A. Mostafavi and T. Shamspur, M. Afzali, A. Mostafavi and T. Shamspur, Organic Electronics, 2020, 86, 105907. "Performance enhancement of perovskite solar cells by rhenium doping in nano-TiO2 compact layer," Organic Electronics, 86, 105907, 2020.
 A. Baktash, O. Amiri and M. Saadat, " High efficient perovskite solar cells base on niobium doped TiO2 as a buffer layer," Journal of Nanostructures, 10, 119-127, 2020.
 F. Biccari, F. Gabelloni, E. Burzi, M. Gurioli, S. Pescetelli, A. Agresti, A. E. Del Rio Castillo, A. Ansaldo, E. Kymakis, and F. Bonaccorso, "Graphene‐based electron transport layers in perovskite solar cells: a step‐up for an efficient carrier collection," Advanced Energy Materials, 7, 1701349, 2017.
 G. S. Han, Y. H. Song, Y. U. Jin, J.-W. Lee, N.-G. Park, B. K. Kang, J.-K. Lee, I. S. Cho, D. H. Yoon, and H. S. Jung, "Reduced graphene oxide/mesoporous TiO2 nanocomposite based perovskite solar cells," ACS applied materials & interfaces, 7, 23521-23526, 2015.
 F. Giordano, A. Abate, J. P. C. Baena, M. Saliba, T. Matsui, S. H. Im, S. M. Zakeeruddin, M. K. Nazeeruddin, A. Hagfeldt, and M. Graetzel, "Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells," Nature communications, 7, 1-6, 2016.
 X. Yin, Y. Guo, Z. Xue, P. Xu, M. He, and B. Liu, "Performance enhancement of perovskite-sensitized mesoscopic solar cells using Nb-doped TiO2 compact layer," Nano Research, 8, 1997-2003, 2015.
 S. Sidhik, A. Cerdan Pasaran, D. Esparza, T. Lopez Luke, R. Carriles, and E. De la Rosa, "Improving the optoelectronic properties of mesoporous TiO2 by cobalt doping for high-performance hysteresis-free perovskite solar cells," ACS applied materials & interfaces, 10, 3571-3580, 2018.
 J. H. Heo, M. S. You, M. H. Chang, W. Yin, T. K. Ahn, S.-J. Lee, S.-J. Sung, D. H. Kim, and S. H. Im, "Hysteresis-less mesoscopic CH3NH3PbI3 perovskite hybrid solar cells by introduction of Li-treated TiO2 electrode," Nano Energy, 15, 530-539, 2015.
 T. Umeyama, D. Matano, J. Baek, S. Gupta, S. Ito, V. Subramanian, and H. Imahori, "Boosting of the performance of perovskite solar cells through systematic introduction of reduced graphene oxide in TiO2 layers," Chemistry Letters, 44, 1410-1412, 2015.
 Q. Luo, Y. Zhang, C. Liu, J. Li, N. Wang, and H. Lin, "Iodide-reduced graphene oxide with dopant-free spiro-OMeTAD for ambient stable and high-efficiency perovskite solar cells," Journal of Materials Chemistry A, 3, 15996-16004, 2015.
 A. Agresti, S. Pescetelli, A. L. Palma, A. E. Del Rio Castillo, D. Konios, G. Kakavelakis, S. Razza, L. Cinà, E. Kymakis, and F. Bonaccorso, "Graphene interface engineering for perovskite solar modules: 12.6% power conversion efficiency over 50 cm2 active area," ACS Energy Letters, 2, 279-287, 2017.
 H. Zheng, X. Xu, S. Xu, G. Liu, S. Chen, X. Zhang, T. Chen, and X. Pan, "The multiple effects of polyaniline additive to improve the efficiency and stability of perovskite solar cells," Journal of Materials Chemistry C, 7, 4441-4448, 2019.
 H. Zheng, L. Zhu, L. Hu, S. Yang, S. Chen, A. Alsaedi, T. Hayat, Y. Huang, X. Pan, and S. Dai, "Promoting perovskite crystal growth to achieve highly efficient and stable solar cells by introducing acetamide as an additive," Journal of Materials Chemistry A, 6, 9930-9937, 2018.
 Z. Tang, S. Uchida, T. Bessho, T. Kinoshita, H. Wang, F. Awai, R. Jono, M. M. Maitani, J. Nakazaki, and T. Kubo, "Modulations of various alkali metal cations on organometal halide perovskites and their influence on photovoltaic performance," Nano Energy, 45, 184-192, 2018.
 H. Uratani and K. Yamashita, "Charge carrier trapping at surface defects of perovskite solar cell absorbers: a first-principles study," The journal of physical chemistry letters, 8, 742-746, 2017.
 J.-W. Lee, S.-H. Bae, N. De Marco, Y.-T. Hsieh, Z. Dai, and Y. Yang, "The role of grain boundaries in perovskite solar cells," Materials today energy, 7, 149-160, 2018.
 B.-X. Chen, H.-S. Rao, W.-G. Li, Y.-F. Xu, H.-Y. Chen, D.-B. Kuang, and C.-Y. Su, "Achieving high-performance planar perovskite solar cell with Nb-doped TiO2 compact layer by enhanced electron injection and efficient charge extraction," Journal of Materials Chemistry A, 4, 5647-5653, 2016.