Synergistic Effect of Lewis Base Polymers and Graphene in Enhancing the Efficiency of Perovskite Solar Cells

Abstract

Incorporating Lewis base polymers into a perovskite layer has been demonstrated as one of the most effective routes to passivate trap states at the grain boundaries, whereas the inferior electrical conductivity of polymers than that of perovskite would inevitably hinder charge transport across the perovskite grains. Herein, we reported a strategy of utilizing highly conductive graphene/Lewis base polymer (PM6 or PM7) composites as additives in perovskite, which simultaneously passivates the defects and facilitates charge transport in the film. We further revealed in the work that halogen elements (Cl/F) in the polymer (PM6/PM7) can p-dope the graphene and endow it with higher hole-transport selectivity, which is of critical importance as ambipolar charge transport without selectivity would induce significant charge recombination in graphene. By this design, we achieved an outstanding efficiency of 21.21%, which is significantly higher than that of the pristine device without treatment. The device also exhibited impressive stability by retaining 90% of its initial power conversion efficiency after 480 h aging in ambient air with a ∼35% relative humidity at room temperature.

Improved phase stability of CsPbI2Br perovskite by released microstrain toward highly efficient and stable solar cells

“…Figure 1B shows the energy level alignment of the PSC device, where highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of BTEC‐2F are determined from the ultraviolet photoelectron spectroscopy (UPS) spectra in Figure S1A and absorption spectra in Figure S1B, and those of other layers are referred to previous literature 19 . It is seen that BTEC‐2F forms a HOMO energy cascade between CsPbI 2 Br and Spiro‐OMeTAD, which expects to decrease the energy losses and thus increase open‐circuit voltage ( V OC ) of the device 20 . Additionally, as an electron‐donor material with good hole mobility, BTEC‐2F could improve the hole transporting and electron blocking ability, thereby suppressing the carrier recombination at the interface.…”

TADF Molecule as an Interfacial Layer with Cascade Energy Alignment Enabling High Open-Circuit Voltage for 3D/2D Perovskite Solar Cells

“…To deeply understand the influence of M1 on the carrier recombination process in the 3D/2D PSCs, we measured J sc and V oc dependence on the incident light intensity ( P light ) Figure a, V oc and light intensity show a linear relationship on the natural logarithmic scale V oc ∝ ( nkT / q )­ln­( P light ), where nkT / q is the slope, k is the Boltzmann’s constant, T is the absolute temperature, and q is the fundamental charge.…”

Strategies for high‐performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

“…After that, the mixture of MA + and HC(NH 2 ) 2 + (FA + ) organic cations were used to prepare FA 0.85 MA 0.15 Pb(I 0.85 Br 0.15 ) 3 (efficiency: 17.9%), 13 FA 0.95 MA 0.05 Pb(I 0.95 Br 0.05 ) 3 (efficiency: >20%), 14–16 and FA 0.92 MA 0.08 PbI 3 (efficiency: 23.7%) 17 . Moreover, our group has also achieved a series of high‐efficiency HPSCs, such as MAPbI 3 (efficiency: >15%), 18–20 Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 (efficiency: >20%) 21 and Cs 0.05 FA 0.79 MA 0.16 Pb(I 0.83 Br 0.17 ) 3 (efficiency: >20%) 22 devices. Generally speaking, the high‐efficiency is a hallmark of high‐performance HPSCs.…”

“…Pb(I 0.85 Br 0.15 ) 3 (efficiency: >20%) 21 and Cs 0.05 FA 0.79 MA 0.16 Pb(I 0.83 Br 0.17 ) 3 (efficiency: >20%) 22 devices. Generally speaking, the high-efficiency is a hallmark of highperformance HPSCs.…”