Effects of Adding Alkali Metals and Organic Cations to Cu-Based Perovskite Solar Cells

Abstract

First-principles electronic band calculations were used to investigate the effects of alkali metals and organic cations added to Cu-based perovskite solar cells. The copper d-orbital band was slightly above the valence-band maximum and functioned as an acceptor level for carrier generation. Excitation from iodine p-orbitals and copper d-orbitals to alkali metal s-orbitals could suppress carrier recombination and promote carrier transport. Experimental solar conversion efficiencies increased after adding both Cu and Na, in agreement with the calculations. Total-energy calculations indicated that the perovskite crystal stability increased with the addition of ethyl ammonium, although the total energy decreased with the addition of Cu and Na.

First-principles calculations and device characterizations of formamidinium-cesium lead triiodide perovskite crystals stabilized by germanium or copper

“…The perovskite crystals with supercells of 2 × 2 × 2 as cluster models were constructed, as reported in the previous works. [51][52][53][54] The molecular behavior and thermodynamic stabilities of Ge, Cu and organic cations were calculated by CPMD. After equilibration of the electronic and atomic states, MD calculations were performed at a constant temperature of 300 K. Planewave basis set cut offs for the wave functions and charge density were set at 50 and 200 Rydberg.…”

Effects of alkali metals or Cu+ addition to α-FAPbI3 perovskite crystals on electronic structures and photovoltaic properties

“…[36][37][38][39] In addition, simultaneous addition of CuBr 2 with alkali elements and organic cations provided reduction of crystal lattice distortion, suppression of defects, and improvement of device stability. [40][41][42][43] However, first-principles calculations and experiments have shown that the introduction of Cu 2+ into the B site in perovskite crystals destabilizes the crystal structure and reduces device stability. 44) For device durability, it was reported that the simultaneous addition of Cu 2+ and stable organic cations compensates the structural destabilization caused by Cu 2+ substitution.…”

First-principles calculation analysis and photovoltaic properties of Cu compound-added perovskite solar cells

“…[9][10][11][12][13] These improvements in the film qualities of the perovskite compounds were attributed to the introduction of Cu, which delayed the growth rate of perovskite crystals. 14) Co-addition of Cu and alkali metals to MA-based perovskite has also been reported to enhance photovoltaic properties [15][16][17][18] or device stabilities. [18][19][20] The Cu addition reduced the crystal lattice distortion, and the alkali metals migrated to the vacancy sites due to MA desorption, suppressing the lattice defects.…”

“…The previous studies by the first-principles calculations indicated that the crystal structure would be stabilized by introducing ethylammonium (EA), which have a larger ionic radius than MA. 16,23) It has been reported that the EA addition to perovskite precursor solutions promoted crystal growth. [24][25][26] The additions of guanidinium (GA), which has a larger ionic radius than EA, has improved the crystallinity and grain sizes of perovskite compounds.…”