Revealing buried heterointerface energetics towards highly efficient perovskite solar cells

Surface Modification in CsPb0.5Sn0.5I2Br Inorganic Perovskite Solar Cells: Effects of Bifunctional Dipolar Molecules on Photovoltaic Performance

“…Figure shows the energy level diagram of PCBM and CsPb 0.5 Sn 0.5 I 2 Br with different modifiers (the calculation method of energy level is shown in Figure S17). Generally, in opposition to the flat band at the interface, charge transfer at the heterointerfaces (CsPb 0.5 Sn 0.5 I 2 Br/PCBM) usually leads to an abrupt step in vacuum level, which is often referred to as the electron extraction barrier. , For the control CsPb 0.5 Sn 0.5 I 2 Br/PCBM heterointerface (Figure a), the work functions ( W F ) are 4.36 and 4.16 eV for CsPb 0.5 Sn 0.5 I 2 Br surface and CsPb 0.5 Sn 0.5 I 2 Br bulk, respectively, which leads to the formation of an interface electron extraction barrier of 0.20 eV. In addition, the upward band bending caused by the surface undercoordinated Sn 2+ of perovskite occurs at the heterointerfaces, which severely hinders the extraction of charge.…”

Molecular Bridge on Buried Interface for Efficient and Stable Perovskite Solar Cells

“…To quantify the trap density in perovskite films, we performed space-charge limited current (SCLC) measurement of the ETL-only devices with a structure of FTO/ SnO 2 /(w/o or w GDA)/perovskite/ [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/Au. The corresponding dark J-V characteristics are shown in Figure 5f.…”

“…The compact contact and well‐aligned energy levels between ETL and perovskite film allow for efficient charge extraction, suppressed charge recombination and improved long‐term device stability [5] . On the contrary, loose contact and extraction barriers lead to undesired accumulation of charge carriers, which causes space charge regions and a high voltage drop at the interface, leading to enhanced charge recombination and therefore reducing the collection efficiency at a certain voltage and thus the FF, along with possible hysteresis [6] . In addition, defects located at the interface and grain boundaries (GBs) of perovskite films [7] can induce nonradiative charge recombination [8] and perovskite degradation [9] .…”

In Situ Reconstruction of Hole‐Selective Perovskite Heterojunction with Graded Energetics Toward Highly Efficient and Stable Solar Cells

“…[10][11][12][13][14][15] Moreover, the degree of the matched energetics at the heterojunction between perovskite photoactive layer and charge transport layer that offers unique control of charge extraction dynamics is the other important source for nonradiative recombination. [16][17][18][19] It is well established that the intrinsic surface energetics of perovskite film highly depends on the work function (WF) of the underlying layer due to the self-doping nature of perovskites. [20][21][22] For example, in regular n-i-p (inverted p-i-n) architectural device, the perovskite grown on a cathode (anode) with a low (high) WF preferentially features a more n-type (p-type) surface, which implies that the spontaneous perovskite surface energetics are detrimental for the electronic contact with the upper deposited p-type hole (n-type electron) transport layer and impede charge extraction across the heterojunction.…”