Triple-cation mixed-halide perovskites: towards efficient, annealing-free and air-stable solar cells enabled by Pb(SCN)2 additive

Abstract

Organo-metal halide perovskites have suffered undesirably from structural and thermal instabilities. Moreover, thermal annealing is often indispensable to the crystallization of perovskites and removal of residual solvents, which is unsuitable for scalable fabrication of flexible solar modules. Herein, we demonstrate the non-thermal annealing fabrication of a novel type of air-stable triple-cation mixed-halide perovskites, FA0.7MA0.2Cs0.1Pb(I5/6Br1/6)3 (FMC) by incorporation of Pb(SCN)2 additive. It is found that adding Pb(SCN)2 functions the same as thermal annealing process by not only improving the crystallinity and optical absorption of perovskites, but also hindering the formation of morphological defects and non-radiative recombination. Furthermore, such Pb(SCN)2-treated FMC unannealed films present micrometer-sized crystal grains and remarkably high moisture stability. Planar solar cells built upon these unannealed films exhibit a high PCE of 14.09% with significantly suppressed hysteresis phenomenon compared to those of thermal annealing. The corresponding room-temperature fabricated flexible solar cell shows an impressive PCE of 10.55%. This work offers a new avenue to low-temperature fabrication of air-stable, flexible and high-efficiency perovskite solar cells.

Defects engineering for high-performance perovskite solar cells

“…As a result, the average Voc of FAPbI 3 devices was enhanced due to reduced non-radiative recombination, and the J-V hysteresis was decreased. 73 In addition to coordinate with PbI 2 , precursors composed of non-PbI 2 precursor, such as lead chloride (PbCl 2 ), 36,37 Lead thiocyanate (Pb(SCN) 2 ) , 75 have also been developed to increase the grain size of perovskite films by the formation of Lewis acid-base intermediate. These intermediates could slow down the perovskite formation process and thus improve the growth of the crystal domains during annealing.…”

Photodetectors Based on Organic–Inorganic Hybrid Lead Halide Perovskites

“…Over the past few years, OIHPs have been attracting the attention of a great number of scientific researchers with the aim to study the fundamental photophysics and practical applications of these materials. As a result, a variety of unprecedented fruits have been yielded, which has been described as a “perovskite fever.”12, 13, 14, 15, 16 More importantly, the skyrocketing PCE of PSCs does not seem to hit an insurmountable bottleneck, further revealing the significance of OIHPs‐related studies 17, 18, 19. In addition to intensive studies on PSCs, OIHPs also hold great potential in many other fields such as field effect transistors (FETs), light emitting diodes (LEDs), and photodetectors owing to the remarkable optoelectronic characteristics of OIHPs (e.g., high external quantum efficiency (EQE) over a wide absorption spectrum, high absorption coefficients, tunable optical band gaps, low trap density, reduced charge carrier recombination rates, and long charge carrier diffusion lengths and lifetimes) 20, 21, 22, 23, 24, 25, 26.…”

Low‐Temperature Processed, Efficient, and Highly Reproducible Cesium‐Doped Triple Cation Perovskite Planar Heterojunction Solar Cells

“…FAPbI 3 has the highly unfavorable non‐perovskite hexagonal δ‐phase (yellow phase) and a perovskite α‐phase (black phase), of which α‐phase could transfer to a photoinactive α‐phase and/or coexist of α‐phase and δ‐phase at room temperature . Similarly, the photoactive CsPbI 3 perovskite would just exist stable over 300 °C and it is a photoinactive orthorhombic δ‐phase at room temperature . Therefore, it is very important to design humidity and thermal stable perovskite materials for high‐performance PSCs.…”