High Efficiency and High Open Circuit Voltage in Quasi 2D Perovskite Based Solar Cells

Abstract

An important property of hybrid layered perovskite is the possibility to reduce its dimensionality to provide wider band gap and better stability. In this work, 2D perovskite of the structure (PEA)2(MA)n–1PbnBr3n+1 has been sensitized, where PEA is phenyl ethyl‐ammonium, MA is methyl‐ammonium, and using only bromide as the halide. The number of the perovskite layers has been varied (n) from n = 1 through n = ∞. Optical and physical characterization verify the layered structure and the increase in the band gap. The photovoltaic performance shows higher open circuit voltage (Voc) for the quasi 2D perovskite (i.e., n = 40, 50, 60) compared to the 3D perovskite. Voc of 1.3 V without hole transport material (HTM) and Voc of 1.46 V using HTM have been demonstrated, with corresponding efficiency of 6.3% and 8.5%, among the highest reported. The lower mobility and transport in the quasi 2D perovskites have been proved effective to gain high Voc with high efficiency, further supported by ab initio calculations and charge extraction measurements. Bromide is the only halide used in these quasi 2D perovskites, as mixing halides have recently revealed instability of the perovskite structure. These quasi 2D materials are promising candidates for use in optoelectronic applications that simultaneously require high voltage and high efficiency.

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

“…Quasi-2D perovskites have demonstrated interesting lightemitting, [1][2][3] lasing, [4,5] and photovoltaic [6][7][8] properties with superior stabilities. Essentially, quasi-2D perovskites are formed with the Ruddlesden-Poper perovskite (RPP) nanoplates separated by www.advmat.de www.advancedsciencenews.com CW 980 nm excitation.…”

“…[20] On the other hand, it has been found that the edge states can be formed in 2D perovskites with light-emitting properties below the bandgap. Polarizationdependent up-conversion PL studies reveal that the gap states experience the orbit-orbit interaction through Coulomb polarization to form spatially extended states toward developing multi-photon up-conversion light emission in quasi-2D perovskites.Quasi-2D perovskites have demonstrated interesting lightemitting, [1][2][3] lasing, [4,5] and photovoltaic [6][7][8] properties with superior stabilities. We should note that an up-conversion ASE was indeed observed at 720 nm in inorganic 3D perovskite (CsPbI 3 ) nanoplates under the infrared pulse laser excitation of 1200 nm.…”

Benefiting from Spontaneously Generated 2D/3D Bulk‐Heterojunctions in Ruddlesden−Popper Perovskite by Incorporation of S‐Bearing Spacer Cation

“…The generic molecular formula of 2D RP lead iodide perovskites can be written as (L) 2 A n−1 Pb n I 3n+1 where L + is alkylammonium cation-typically phenylethylamine (C 8 H 11 N, PEA) and butylamine (n-BA), A + is monovalent organic cations such as CH 3 NH 3 + , and the n value is the number of Pb−I octahedral layers between adjacent spacers. [21][22][23][24][25][26][27] 2D Ruddlesden-Popper (RP) perovskite solar cells have manifested superior operation durability yet inferior charge transport compared to their 3D counterparts. [19] Besides, the bandgap (E g ) of 2D perovskites increases with narrowing the thickness of the quantum wells (i.e., decreasing the n value), which is incompatible with making use of the full solar spectrum.…”

Two-dimensional organic-inorganic hybrid perovskite: from material properties to device applications

“…Quan et al [49] supposed that lower mobility leads to slower charge extraction, followed by carriers accumulation which enables higher V OC . Meanwhile, Cohen et al [93] inferred that lower mobility of 2D perovskite relieves the carrier accumulation at selective contact, and therefore reduces the quenching at interface and results in higher V OC . The V OC could potentially be further improved through transport materials selecting and contact interface engineering [6,14].…”