Emerging Photovoltaics

**163**

**Chapter 10**

**Abstract**

Solar Cells

*and Mohamed M. Rashad*

challenges, and future prospects.

with high molar extinction coefficient (≈104

**1. Introduction**

**Keywords:** 2D, 3D, perovskite solar cells, stability, efficiency

Mixed 2D-3D Halide Perovskite

*Ahmed Mourtada Elseman, Nasr Gad, Mostafa El-Aasser* 

The 3D-perovskite halides have gained a considerable reputation versus their counterpart semiconductor materials since they achieved a remarkable high-power conversion efficiency of 25.2% within a decade. Perovskite solar cells also have some problems as lattice degradation and sensitivity against moisture, oxygen, and strong irradiation. The perovskite instability is the drawback in front of this emerging technology towards mass production and commercialization. 2D-perovskites, with the general formula A2Bn − 1MnX3n + 1, have been recently introduced to overcome some of the drawbacks of the stability of 3D-perovskites; however, this is at the expense of sacrificing a part of the power conversion efficiency. Mixed 2D/3D perovskites could solve this dilemma towards the way to high stabilityefficiency perovskites. The research is expected to obtain highly stable and efficient mixed 2D/3D perovskite solar cells in the few coming years. This chapter reviews 2D-perovskites' achieved progress, highlighting their properties, current trends,

Perovskites are among the essential material science topics in the last decades due to their low-cost, solution-processed devices and exceptional optoelectronic properties [1–28]. The most studied compositions are represented by the formula ABX3 (organic cation A is larger than the metal cation B, and X is a halide anion). For example, methylammonium lead tri-iodide (CH3NH3PbI3 or MAPbI3), the other halide variants such as CH3NH3PbBr3 and mixed halides, CH3NH3PbI3-xClx [29–31]. The most advantages of 3D-perovskite (CH3NH3PbI3) are combining direct bandgap

low exciton binding energies (≈10–50 meV), which cause long-range free-carrier diffusion lengths (≈100 nm). The perovskite is unique in such a way that its efficiency boosted up from 3.8% to 23.7% in just few years as compared to all other types of traditional solar cells. However, the lack of durability of these materials (hydrophilic cations) due to thermal instability and degradation upon exposure to humidity, U.V. radiation, and the electric field is still a significant barrier to

–105

M−1 cm−1), low trap densities,

*Alaa E. Abd El-Samad, Radwa S. Mostafa,* 

*Hager H. Zeenelabden, Menahtullah M. Mabrouk,* 
