High Efficiency Of Sn-pb Perovskite Solar Cells And Its Photoelectric Performance

The photoelectric conversion efficiency of perovskite solar cells has increased from 3.8%to 25.5%nearly a decade,which has attracted wide attention in the field of photovoltaic.Most of the high efficiency batteries have been limited due to the toxic lead element.It is necessary to develop green perovskite solar cells.Tin-based perovskite is a low-toxic photovoltaic material with ideal bandgap and high carrier mobility.At present,the efficiency of tin-lead mixed perovskite solar cells has reached21.7%,which also has great potential in photovoltaic applications.However,due to the shortcomings of easy oxidation and fast crystallization rate,these factors limit the further improvement of efficiency.This paper mainly studies the efficiency and stability of lead-tin perovskite by additive engineering.It mainly includes the following three parts:(1)Aiming at the defects at the grain boundary of Sn-Pb perovskite film and the non-radiative recombination problem caused by Sn²⁺oxidation.We introduced ethyl ammonium iodide(EAI)into precursor solution.After the introduction of EAI,the grain size of perovskite thin films was improved,and the nucleation rate was delayed.The optimized device with power conversion efficiency(PCE)of 17.57%was obtained,and the stability of the device was also improved.(2)On the basis of the first part,aiming at the separation of Sn-Pb mixed perovskite phase and the low current density,we prepared the two-dimensional(2D)/three-dimensional(3D)heterojunction structure of Ruddlesden-Popper phase.By introducing a small amount of(3.75 mol%)organic cation 2-(4-fluorophenyl)ethyl ammonium iodide(FPEAI)into the precursor solution,FPEAI induced the vertical arrangement of Sn-Pb perovskite crystals in the substrate to grow.This provides an effective channel for the extraction of carriers.In addition,the phase separation phenomenon is first found in the original three-dimensional(3D)tin-lead perovskite,but it is inhibited by the existence of quasi-two-dimensional perovskite.The high current density of 28.42 m A·cm^-2 was obtained,and the PCE of the optimal device was17.51%,showing good stability.(3)Aiming at the stability problem of Sn-Pb mixed perovskite,based on the study of R-P phase,the D-J phase 2D/3D heterojunction structure without van der Waals gap between perovskite layers was constructed by introducing 1,4-butanediamine diiodide(BDADI)into the precursor solution,and the PCE of the device reached 19.02%.In addition,2D/3D mixed perovskite films and devices exhibit better stability than 3D perovskites...