B‐Site Co‐Alloying with Germanium Improves the Efficiency and Stability of All‐Inorganic Tin‐Based Perovskite Nanocrystal Solar Cells

Abstract

Colloidal lead-free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size-tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead-free solar cells, yet showing highly unstable characteristics in ambient conditions. Here, we propose the synthesis of all-inorganic mixture Sn-Ge perovskite nanocrystals, demonstrating the role of Ge 2+ in stabilizing Sn 2+ cation while enhancing the optical and photophysical properties. The partial replacement of Sn atoms by Ge atoms in the nanostructures effectively fills the high density of Sn vacancies, reducing the surface traps and leading to a longer excitonic lifetime and increased photoluminescence quantum yield. The resultant Sn-Ge nanocrystals-based devices show the highest efficiency of 4.9 %, enhanced by nearly 60 % compared to that of pure Sn nanocrystals-based devices.

Halide Perovskite Nanocrystal Emitters

“…[ 2,3 ] PNCs are characterized by strong absorption coefficients, high charge carrier mobilities (1–10 cm 2 V −1 s −1 ), up to near‐unity PLQY, high emission color purity, and easily tunable photoluminescence (PL) emission in a wide spectral region (390–1050 nm [ 4 ] ). [ 5–8 ] As a result, their potential for a broad range of applications, such as light‐emitting diodes (LEDs), [ 9,10 ] solar cells, [ 11,12 ] photodetectors, [ 13,14 ] and lasers, [ 15 ] has been recently exploited with highly promising results.…”

Progresses on Novel B‐Site Perovskite Nanocrystals

“…have reported B‐site coalloying with Ge to improve both the stability and efficiency of the CsSnI 3 NCs by an MHIM. [ 68 ] In a typical hot‐injection synthesis, SnI 2 and GeI 2 were dissolved into the solvent consist of ODE, OA, and OLAM at certain temperature. Then some Cs‐oleate precursor was swiftly injected into the as‐prepared Sn–Ge precursor solvent with the reaction temperature increasing to 240 °C.…”

“…aimed to fill the high density of Sn vacancies of the CsSnX 3 NCs, and they considered doping as an effective way. [ 68 ] The PL spectrum of CsSn 0.6 Ge 0.4 I 3 NCs exhibits a main PL peak at around 780 nm (1.6 eV) with an FWHM of 65 nm. There is a small PL subpeak at around 725 nm being observed, which originates from a small amount of SnGe‐based nanorods formed together with the CsSn 0.6 Ge 0.4 I 3 NCs.…”

“…have tried to improve the performance of LF perovskite solar cells using CsSn 0.6 Ge 0.4 I 3 NCs films. [ 68 ] As presented in Figure 21C (i), the full n–i–p LF perovskite solar cell structure is FTO/c‐TiO 2 /CsSn 0.6 Ge 0.4 I 3 NCs/Spiro‐OMeTAD/MoO 3 /Au, and the cross‐sectional SEM image of the CsSn 0.6 Ge 0.4 I 3 NCs‐based cells is presented in Figure 21C (ii). Owing to the partial replacement of Sn atoms by Ge atoms, the resultant CsSn 0.6 Ge 0.4 I 3 NCs films exhibited a longer excitonic lifetime and improved PLQE.…”

Improving Stability and Colloidal Dispersity of CsPbBr3@SiO2 Nanoparticles Based on In-Situ Synthesis in Entropy Ligands Functionalized SiO2 Nanoreactor

“…Nevertheless, their intrinsic ionic structural instability makes them labile upon external disturbance, e.g., humidity, thermal treatment, and light illumination, impeding their practical applications [10][11][12][13][14]. Given this, chemical and structural strategies including surface modification, encapsulation approaches, component engineering, and heteratomic doping remain cutting-edge research and hot spots on improving the stability of PNCs [15][16][17][18].…”