A comprehensive theoretical study of halide perovskites ABX3 |
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| Affiliation: | 1. College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065, PR China;2. Department of Biotechnology, University of Verona, Strada Le Grazie 15, I-37134 Verona, Italy;3. Institute of Physics, University of Tartu, W. Ostwald Str 1, Tartu 50411, Estonia;4. Institute of Physics, Jan D?ugosz University, Armii Krajowej 13/15, PL-42200 Cz?stochowa, Poland;1. Department of Physics, Indian Institute of Technology Patna, Bihta, Patna, Bihar, India;2. Department of Applied Science, Feroze Gandhi Institute of Engineering and Technology, Raebareli, Uttar Pradesh, India;3. Department of Physics, Govt M.A.M College, Jammu, Jammu and Kashmir, India;4. Department of Physics, Barkatullah University, Bhopal, Madhya Pradesh, India;5. Department of Physics, School of Chemical Engineering & Physical Sciences Lovely Professional University, Phagwara, Punjab, India;1. Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China;2. Synergetic Innovation Center for Quantum Effects and Applications (SICQEA), Hunan Normal University, Changsha 410081, China;1. School of Physical Science and Technology, Xinjiang University, 666 Shengli Road, Urumqi 830046, China;2. Department of Physics, Tamkang University, New Taipei City 25137, Taiwan;1. Department of Physics, Hazara University Mansehra, KP, Pakistan;2. Department of Physics, King Khalid University, P. O. Box 9004, Abha, 61413, Saudi Arabia;3. Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar, Campus universitaire, 1060, Tunis, Tunisia;4. Materials Modelling Lab, Department of Physics, Islamia College University, 25120, Peshawar, Pakistan;5. Department of Mathematics & Natural Sciences, Prince Mohammad Bin Fahd University, P. O. Box 1664, Alkhobar, 31952, Saudi Arabia;1. Department of Physics, Nirmalagiri College, Kannur University, Kannur, Kerala 670701, India;2. Rajagiri School of Engineering & Technology, Rajagiri Valley, Kakkanad, Kochi, Kerala 682039, India |
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| Abstract: | Solar cells based on halide perovskites have recently been attractive due to their excellent power conversion efficiency (PCE), lower cost and simple manufacture. Here, a series of halide perovskites (ABX3: A = CH3NH3, CH(NH2)2, Cs, Rb; B = Pb, Sn, Ge; X = I, Br, Cl, F) were investigated by Density Functional Theory (DFT) calculations, together with Shockley-Queisser Maximum Solar Cell Efficiency (S-Q) and Spectroscopic Limited Maximum Efficiency (SLME) mathematical models. The results indicate that: the electronic structure of germanium perovskites bears a close similarity to that of lead perovskites with a small energy difference between the nonbonding orbital and antibonding orbitals, but with a large energy difference comparing with that of tin perovskites (0.6–1.7 eV for CsGeI3 at Z point of the Brillouin zone, 0.7–1.4 eV for CH3NH3PbI3 and 1.4–2.2 eV for CH3NH3SnI3 at R point of the Brillouin zone), which is attributable to the atomic level, where the 4s orbital energy of Ge (?11.5 eV) is close to the 6s orbital energy of Pb (?11.6 eV), but the 5s orbital energy of Sn (?10.1 eV) is significantly high. Therefore, germanium perovskites possess as high absorption coefficient around solar spectrum as lead perovskites, while tin perovskites only have low absorption coefficient, which makes the short-circuit current of CsGeI3 and CH3NH3PbI3 (0.017 Acm?2 and 0.016 Acm?2, simulated by SLME with a 200 nm absorber under AM1.5G) are higher than that of CH3NH3SnI3 (0.015 Acm?2) even if the bandgap of CsGeI3 and CH3NH3PbI3 (1.51 eV and 1.55 eV) are larger than that of CH3NH3SnI3 (1.21 eV). Meanwhile, the effective mass of electrons and holes are approximate for germanium perovskites and lead perovskites (0.14:0.19 for CsGeI3 and 0.12:0.12 for CH3NH3PbI3), indicating a balanced electrons and holes transport, whereas the electrons transport is much slower than the holes transport for tin perovskites due to the effective mass of electron is much larger than that of hole (0.17:0.04 for CH3NH3SnI3). As a result, the PCE of CsGeI3 (27.9%) and CH3NH3PbI3 (26.7%) is higher than that of CH3NH3SnI3 (19.9%). |
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| Keywords: | Perovskites Theoretical study Electrical Optical Lead free |
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