Abstract
Ruddlesden–Popper (RP) phase metal halide organo perovskites are being extensively studied due to their quasi-two dimensional (2D) nature which makes them an excellent material for several optoelectronic device applications such as solar cells, photo-detectors, light emitting diodes (LEDs), lasers etc. While most of reports show use of linear carbon chain based organic moiety, such as n-Butylamine, as organic spacer in RP perovskite crystal structure, here we report a new series of quasi 2D perovskites with a ring type cyclic carbon group as organic spacer forming RP perovskite of type (CH)2(MA)n−1PbnI3n+1; CH = 2-(1-Cyclohexenyl)ethylamine; MA = Methylamine). This work highlights the synthesis, structural, thermal, optical and optoelectronic characterizations for the new RP perovskite series n = 1–4. The demonstrated RP perovskite of type for n = 1–4 have shown formation of highly crystalline thin films with alternate stacking of organic and inorganic layers, where the order of PbI6 octahedron layering are controlled by n-value, and shown uniform direct bandgap tunable from 2.51 eV (n = 1) to 1.92 eV (n = 4). The PL lifetime measurements supported the fact that lifetime of charge carriers increase with n-value of RP perovskites [154 ps (n = 1) to 336 ps (n = 4)]. Thermogravimetric analysis (TGA) showed highly stable nature of reported RP perovskites with linear increase in phase transition temperatures from 257 °C (n = 1) to 270 °C (n = 4). Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) are used to investigate the surface morphology and elemental compositions of thin films. In addition, the photodetectors fabricated for the series using (CH)2(MA)n−1PbnI3n+1 RP perovskite as active absorbing layer and without any charge transport layers, shown sharp photocurrent response from 17 nA/cm2 for n = 1 to 70 nA/cm2 for n = 4, under zero bias and low power illumination conditions (470 nm LED, 1.5 mW/cm2). Furthermore, for lowest bandgap RP perovskite n = 4, (CH)2MA3Pb4I13 the photodetector showed maximum photocurrent density of ~ 508 nA/cm2 at 3 V under similar illumination condition, thus giving fairly large responsivity (46.65 mA/W). Our investigations show that 2-(1-Cyclohexenyl)ethylamine based RP perovskites can be potential solution processed semiconducting materials for optoelectronic applications such as photo-detectors, solar cells, LEDs, photobatteries etc.
Highlights
Etc.[8,9,10,11,12,13,14]
Contrary to the bulk perovskites, the low-dimensional counterpart such as 2D perovskites of type butylamine lead iodide ( C4H9NH3)2PbI4 are studied for their unique strong room-temperature exciton properties, structural flexibility and improved stabilities17,18. 2D metal halide perovskites forms naturally selfassembled quantum well type structures which leads to the formation of excitons with large binding energies (~ 300 meV), owing to the dielectric and quantum confinement effects[19,20]
These RP phase perovskite materials are derivative of 3D perovskites and denoted by the general formula of ( RNH3)2(MA)n−1MnX3n+1 where R NH3 is a large organic cation, MA is methylamine which acts as small organic cation, the integer n represent number of metal halide octahedron MX6 layers between adjacent insulating organic layers comprising of R NH3 and MA, M2+ is a divalent metal cation and X− is a halide anion[17,23,24,25,26]
Summary
Etc.[8,9,10,11,12,13,14]. in spite of excellent optoelectronic properties, these 3D metal halide perovskites suffer from the inherent structural instability in the ambient atmospheric conditions, which limit their utilizations in commercial devices[15,16]. For instance for n = 2 (CH)2(MA)Pb2I7 film, an exciton absorption peak is observed at 567 nm (λ2) along with the characteristic absorbance peak corresponding to n = 1 at 508 nm (λ1) showing the presence of lower n value phase in the RP p erovskites[64].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
