The Interplay between Trap Density and Hysteresis in Planar Heterojunction Perovskite Solar Cells

Abstract

Anomalous current-voltage (J-V) hysteresis in perovskite (PSK) solar cell is open to dispute, where hysteresis is argued to be due to electrode polarization, dipolar polarization, and/or native defects. However, a correlation between those factors and J-V hysteresis is hard to be directly evaluated because they usually coexist and are significantly varied depending on morphology and crystallinity of the PSK layer, selective contacts, and device architecture. In this study, without changing morphology and crystallinity of PSK layer in a planar heterojunction structure employing FACsPbI, a correlation between J-V hysteresis and trap density is directly evaluated by means of thermally induced PbI regulating trap density. Increase in thermal annealing time at a given temperature of 150 °C induces growth of PbI on the PSK grain surface, which results in significant reduction of nonradiative recombination. Hysteresis index is reduced from 0.384 to 0.146 as the annealing time is increased from 5 to 100 min due to decrease in the amplitude of trap-mediated recombination. Reduction of hysteresis by minimizing trap density via controlling thermal annealing time leads to the stabilized PCE of 18.84% from the normal planar structured FACsPbI PSK solar cell.

CH3NH3PbI3 and HC(NH2)2PbI3 Powders Synthesized from Low‐Grade PbI2: Single Precursor for High‐Efficiency Perovskite Solar Cells

“…Upon using MeCN to wash the FAPbI 3 powder,t he FAPbI 3 powder changed to ay ellow color,t he excess amount of FAIw as washed away,a nd the phase changed (FigureS7). [51] As expected, FAPbI 3 crystallized to the black a-phase upon annealing the film deposited by using a solutionw ith high-grade PbI 2 and FAI ( Figure 4c). The XRD patterns Figure 3.…”

Simplified Perovskite Solar Cell with 4.1% Efficiency Employing Inorganic CsPbBr3 as Light Absorber

“…It has been previously reported that the trap‐mediated nonradiative recombination and bimolecular radiative recombination are dominant for degrading the theoretical PCEs of solar cells . Monolithic power output is improved by reducing this photoelectron loss.…”

Surface Chlorination of ZnO for Perovskite Solar Cells with Enhanced Efficiency and Stability

“…To further explain the improved performance and suppressed hysteresis of the device based on ZnO–Cl, the related mechanisms are analyzed in detail through the energy level diagrams. It has been shown that the reverse bias sweep (the pre‐bias higher than V oc ) is more conducive in obtaining higher efficiency, and the energy level diagram of the device is shown in Figure c. The mobile positive and negative ionic charges in the perovskite layer will be separated and has opposite distribution under the applied bias voltage; then, the generated potential strengthens the built‐in electric field ( E bi ) and facilitates transport of the photogenerated charge carrier in the perovskite layer.…”