Carrier Management via Integrating InP Quantum Dots into Electron Transport Layer for Efficient Perovskite Solar Cells

Abstract

Metal oxides are the most efficient electron transport layers (ETLs) in perovskite solar cells (PSCs). However, issues related to the bulk (i.e., insufficient electron mobility, unfavorable energy level position) and interface of metal oxide/perovskite (detrimental surface hydroxyl groups) limit the transport kinetics of photoinduced electrons and prevent PSCs from unleashing their theoretical efficiency potential. Herein, the inorganic InP colloid quantum dots (CQDs) with outstanding electron mobility (4600 cm2 V–1 s–1) and carboxyl (−COOH) terminal ligands were uniformly distributed into the metal oxide ETL to form consecutive electron transport channels. The hybrid InP CQD-based ETL demonstrates a more N-type characteristic with more than 3-fold improvement in electron mobility. The formation of the Sn–O–In bond facilitates electron extraction due to suitable energy level alignment between the ETL and perovskite. The strong interaction between uncoordinated Pb2+ at the perovskite/ETL interface and the −COO– in the ligand of InP CQDs reduces the density of defects in perovskite. As a result, the hybrid InP CQD-based ETL with an optimized InP ratio (18 wt %) boosts the power conversion efficiency of PSCs from 22.38 to 24.09% (certified efficiency of 23.43%). Meanwhile, the device demonstrates significantly improved photostability and atmospheric storage stability.

Regioselective Multisite Atomic-Chlorine Passivation Enables Efficient and Stable Perovskite Solar Cells

“…We first measured the Nyquist diagrams of devices under dark conditions without bias. The 135-TCBP- and 124-TCBP-treated devices exhibit larger composite resistances compared to those of the pristine devices (Figure f ), indicating that the addition of 135-TCBP and 124-TCBP reduces the charge recombination . We then investigated the relationship between V oc and light intensity to elucidate the recombination mechanism in pristine and 135-TCBP- and 124-TCBP-treated devices.…”

“…The 135-TCBP-and 124-TCBP-treated devices exhibit larger composite resistances compared to those of the pristine devices (Figure 3f ), indicating that the addition of 135-TCBP and 124-TCBP reduces the charge recombination. 28 We then investigated the relationship between V oc and light intensity to elucidate the recombination mechanism in pristine and 135-TCBP-and 124-TCBP-treated devices. By plotting V oc versus lnP, the recombination mechanism can be obtained using the equation V oc = (nk B T/q)lnP, where n, k B , T, and q are the constants referred to as the ideality factor, Boltzmann constant, temperature, and elementary charge, respectively.…”

Small molecule-incorporated SnO2 layer for efficient perovskite solar cells

“…1c and d, the O 1s XPS spectrum for SnO 2 film was decontrolled into two peaks located at 530.15 eV and 531.32 eV, respectively. The amounts of lattice oxygen (O L ) and vacancy oxygen (O V ) can be deduced 38 according to the area ratio between the SnO 2 films (main peak area: acromion area =1 : 0.47) and SnO 2 :SSB films (main peak area: acromion area =1 : 1). This indicates additional chemically adsorbed oxygen on the surface of the SnO 2 :SSB film, which reduces the surface hydroxyl groups of SnO 2 and leads to ion recombination.…”

Energy Transfer Induced by TADF Polymer Enables the Recycling of Excitons in Perovskite Solar Cells

“…, where V bi is the built-in potential and N d is the charge density, [39][40][41] V bi of the pristine perovskite device can be determined to be 0.79 V, and the V bi of the P1-modified perovskite device is 0.95 V. The charge density (N d ) can be extracted to be 1. By fitting the spectra in Figure S7 (Supporting Information), the remarkably increased R rec for the device with P1 indicates suppressed charge recombination at perovskite/HTL interfaces.…”

“…Figure 5i depicts the M‐S plots of pristine perovskite and P1‐modified perovskite devices. According to the equation: C −2 = 2( V bi − V )/( A 2 qεε 0 N d ), where V bi is the built‐in potential and N d is the charge density, [ 39–41 ] V bi of the pristine perovskite device can be determined to be 0.79 V, and the V bi of the P1‐modified perovskite device is 0.95 V. The charge density ( N d ) can be extracted to be 1.38 × 10 17 cm −3 and 1.19 × 10 17 cm −3 for pristine perovskite and P1‐modified perovskite‐based PSCs, respectively. The decrement of N d at the perovskite/P1 interface indicates reduced charge accumulation, which should be attributed to the improved charge extraction efficiency at the interface.…”