Perovskite Solar Cells and Tandem Photovoltaics

Dear Colleagues,

Perovskite solar cells (PSCs) based on various materials, such as all-inorganic and organic–inorganic perovskite-based light-absorbing materials, have shown great potential for high-efficiency photovoltaic applications. These perovskite materials have been widely used to prepare single-junction and multi-junction perovskite and perovskite-based tandem solar cells. The performance of these devices depends on several factors, such as light absorption, the bandgap of the materials, charge carrier dynamics and transport, and the interfacial charge transfer phenomenon. Understanding these factors is essential for improving the stability and commercial viability of this astonishing technology. Moreover, developing new materials, mechanisms of research, and device architecture with improved efficiency and stability of perovskite and perovskite-based tandem solar cells is also highly desirable.

This Special Issue of Energies invites original research and review articles on the latest developments in solar cells based on perovskite materials. We are particularly interested in papers that explore the development of new materials, device architectures, and improved photovoltaic and optoelectronic characteristics of perovskite and perovskite-based tandem solar cells. This Special Issue aims to provide a comprehensive overview of the current state of the art and future perspectives in this field. We welcome your submissions to this Special Issue.

Dr. Jongchul Lim
Guest Editor

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• perovskite solar cells
• tandem photovoltaics
• charge transporting materials
• interfacial engineering
• optoelectronic properties

Title: Elucidating Interfacial Hole Extraction and Recombination Kinetics in Perovskite Thin Films
Authors: Sunkyu Kim; Wonjong Lee; Zobia Irshad; Siwon Yun; Hyeji Han; Muhammad Adnan; Hyo Sik Chang; Jongchul Lim
Affiliation: Graduate School of Energy Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea
Abstract: Hybrid organic-inorganic perovskite solar cells (PSCs) are receiving huge attention owing to their marvelous advantages, such as low cost, high efficiency, and superior optoelectronics characteristics. Despite their promising potential, charge-carrier dynamics at the interfaces are still ambiguous, causing carrier recombination and hindering carrier transport, thus lowering the open-circuit voltages (Voc) of PSCs. To unveil this ambiguous phenomenon, we intensively performed various optoelectronic measurements to investigate the impact of interfacial charge-carrier dynamics of PSCs under various light intensities. This is because the charge density can exhibit different mobility and charge transport properties depending on the characteristics of the charge transport layers. We explored the influence of the hole transport layer (HTL) by investigating charge transport properties through photoluminescence (PL) and time-resolved (TRPL) to unveil interfacial recombination phenomena and optoelectronic characteristics. We specifically investigated the impact of various thicknesses of HTLs such as 2,2’ ,7,7’-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9’-spirobifluorene (Spiro-OMeTAD), and poly(triaryl)amine (PTAA) on FA0.71MA0.29Pb(Br0.05I0.95)3 perovskite films. The HTLs are coated on perovskite film by altering the HTL’s concentration and using F4-TCNQ and 4-tert-butylpyridine (tBP) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) as dopants both for Spiro-OMeTAD and PTAA. These HTLs diversified the charge concentration gradients in the absorption layer, thus leading to different recombination rates based on the employed laser intensities. At the same time, the generated charge carriers are rapidly transferred to the interface of the HTL/absorption layer and accumulate holes at the interface because of inefficient capacitance and mobility differences caused by differently doped HTL thicknesses. Notably, the charge concentration gradient is low at lower light intensities and did not accumulate holes at the HTL/absorption layer interface, even though they have high charge mobility. Therefore, this study highlights the importance of interfacial charge recombination and charge transport phenomena to achieve highly efficient and stable PSCs.