正丁醇添加剂制备 CsPbBr3 钙钛矿太阳能电池

Perovskite solar cells (PSCs) have garnered notable attention in the photovoltaic field for their cost-effectiveness, simple fabrication, and high power conversion efficiency (PCE). Since the inception of the first PSC in 2009, significant advancements have been made, with the PCE soaring from 3.8% to 26.1%, nearly matching the efficiency of conventional silicon-based solar cells. Among PSCs, all-inorganic CsPbBr₃ PSCs have emerged as a subject of keen interest owing to their exceptional stability in thermal and humid conditions, in contrast to organic-inorganic PSCs that utilize MAPbBr₃ as light-harvesting materials, which have a limited lifespan due to the instability of organic ammonium cations in the composition. The fabrication of all-inorganic CsPbBr₃ PSCs typically involves a two-step spin-coating method, in which the PbBr₂ layer is initially deposited on fluorine-doped tin oxide conductive glass with an electron or hole transport layer. Subsequently, the CsBr solution is spin-coated onto the PbBr₂ layer and annealed to form the CsPbBr₃ layer. Unlike methanol, the CsBr is dissolved in water at a high concentration to ensure complete reaction with PbBr₂ without causing environmental pollution issues. However, the suboptimal contact between water and PbBr₂ films poses a challenge to the development of PSCs and may result in the generation of more defects and excess CsBr. Consequently, an additive is required for the CsBr aqueous solution to enhance the quality of the perovskite film produced through the two-step spin-coating method, facilitating the uniform spread of the solution on the PbBr₂ film and promoting evaporation to achieve larger CsPbBr₃ grains while inhibiting defects. Consequently, water is utilized to dissolve the CsBr at a high concentration, while employing various volume fractions of additives, reaction times, and annealing durations. It is observed that the utilization of a 1.175 mol L⁻¹ CsBr aqueous solution with a 5% volume fraction of n-butanol (NBA) on the PbBr₂ film, a reaction period of 15 s prior to spin-coating, and an annealing duration of 15 min at 250°C, yields a better morphology and photovoltaic performance compared to the pristine one, solely comprising CsBr aqueous solution. The principal findings and discussions are outlined below: (1) The NBA-doped CsPbBr₃ film exhibits fewer defects and heterophase compared to the pristine film in morphology, as evidenced by scanning electron microscope (SEM) and X-ray diffraction (XRD) measurements. This indicates that the introduction of a 5% volume of NBA enhances the wettability of the CsBr aqueous solution, facilitating improved contact with the PbBr₂ film, and offering additional nucleation sites due to the boiling point difference between water and NBA. (2) In the electrochemical and optical tests, the NBA-doped group exhibits a notable decrease in defect density, effectively mitigating nonradiative charge-carrier recombination. This enhancement is conducive to improving the extraction and mobility of photogenerated carriers, consequently enhancing both the V_OC and PCE of the PSCs. The moderate incorporation of NBA improves the growth of CsPbBr₃ grains and facilitates the reaction between PbBr₂ and CsBr, thereby ameliorating the defects within the perovskite film. This process leads to the development of larger grains, thereby promoting radiative charge-carrier combination and culminating in superior PSC performance. (3) The PSCs with the configuration of FTO/TiO₂/CsPbBr₃/Carbon are fabricated. The NBA-doped PSC can achieve an optimal PCE of 9.92% accompanied by a V_OC of 1.60 V, FF of 85.78%, and J_SC of 7.23 mA cm⁻², which is a significant improvement compared to that of the undoped-device (6.80%). Moreover, the stability of these devices has markedly increased, as evidenced by the fact that after 28 days, the PCE of the optimum device remains above 95%.