Balancing charge carrier transport in a quantum dot P–N Junction toward hysteresis-free high-performance solar cells

ACS Energy Letters American Chemical Society 3 (2018) 1036-1043

Authors:

Yuljae Cho, Bo Hou, Jongchul Lim, Sanghyo Lee, Sangyeon Pak, John Hong, Paul Giraud, A-R Jang, Y-W Lee, Juwon Lee, JE Jang, Henry J Snaith, Stephen Morris, Junginn Sohn, SeungNam Cha, Jong Min Kim

Abstract:

In a quantum dot solar cell (QDSC) that has an inverted structure, the QD layers form two different junctions between the electron transport layer (ETL) and the other semiconducting QD layer. Recent work on an inverted-structure QDSC has revealed that the junction between the QD layers is the dominant junction, rather than the junction between the ETL and the QD layers, which is in contrast to the conventional wisdom. However, to date, there have been a lack of systematic studies on the role and importance of the QD heterojunction structure on the behavior of the solar cell and the resulting device performance. In this study, we have systematically controlled the structure of the QD junction to balance charge transport, which demonstrates that the position of the junction has a significant effect on the hysteresis effect, fill factor, and solar cell performance and is attributed to balanced charge transport.

Nonspiro, Fluorene‐Based, Amorphous Hole Transporting Materials for Efficient and Stable Perovskite Solar Cells

Advanced Science Wiley 5:4 (2018) 1700811

Authors:

Šarūnė Daškevičiū tė, Nobuya Sakai, Marius Franckevičius, Marytė Daškevičienė, Artiom Magomedov, Vygintas Jankauskas, Henry J Snaith, Vytautas Getautis

The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory

Journal of Materials Chemistry C Royal Society of Chemistry 6:15 (2018) 3861-3868

Authors:

IV Kabakova, I Azuri, Z Chen, Pabitra Nayak, Henry Snaith, L Kronik, C Paterson, AA Bakulin, DA Egger

Abstract:

Hybrid organic–inorganic perovskites (HOIPs) have recently emerged as highly promising solution-processable materials for photovoltaic (PV) and other optoelectronic devices. HOIPs represent a broad family of materials with properties highly tuneable by the ions that make up the perovskite structure as well as their multiple combinations. Interestingly, recent high-efficiency PV devices using HOIPs with substantially improved long-term stability have used combinations of different ionic compositions. The structural dynamics of these systems are unique for semiconducting materials and are currently argued to be central to HOIPs stability and charge-transport properties. Here, we studied the impact of ionic composition on phonon speeds of HOIPs from Brillouin spectroscopy experiments and density functional theory calculations for FAPbBr3, MAPbBr3, MAPbCl3, and the mixed halide MAPbBr1.25Cl1.75. Our results show that the acoustic phonon speeds can be strongly modified by ionic composition, which we explain by analysing the lead-halide sublattice in detail. The vibrational properties of HOIPs are therefore tuneable by using targeted ionic compositions in the perovskite structure. This tuning can be rationalized by non-trivial effects, for example, considering the influence of the shape and dipole moment of organic cations. This has an important implications for further improvements in the stability and charge-transport properties of these systems.

Evidence of Nitrogen Contribution to the Electronic Structure of the CH3NH3PbI3 Perovskite

Chemistry - A European Journal Wiley 24:14 (2018) 3539-3544

Authors:

Małgorzata Kot, Konrad Wojciechowski, Henry Snaith, Dieter Schmeißer

High-performance all-polymer solar cells based on fluorinated naphthalene diimide acceptor polymers with fine-tuned crystallinity and enhanced dielectric constants

Nano Energy Elsevier 45 (2018) 368-379

Authors:

Xiaofeng Xu, Zhaojun Li, Junke Wang, Baojun Lin, Wei Ma, Yangjun Xia, Mats R Andersson, René AJ Janssen, Ergang Wang