Electron-enriched thione enables strong Pb-S interaction for stabilizing high quality CsPbI perovskite films with low-temperature processing.

Cesium lead iodide (CsPbI) perovskite is a promising photovoltaic material with a suitable bandgap and high thermal stability. However, it involves complicated phase transitions, and black-phase CsPbI is mostly formed and stabilized at high temperatures (200-360 °C), making its practical application challenging. Here, for the first time, we have demonstrated a feasible route for growing high quality black-phase CsPbI thin films under mild conditions by using a neutral molecular additive of 4(1)-pyridinethione (4-PT).

Self-assembled naphthalimide derivatives as an efficient and low-cost electron extraction layer for n-i-p perovskite solar cells.

Based on self-assembly, novel electron extraction layers (EELs) composed of naphthalimide (NPI) derivatives are constructed for application in n-i-p perovskite solar cells. Upon molecular energy level modulation, the power conversion efficiencies have been largely improved from 5.4% to 16%.

Semi-Locked Tetrathienylethene as a Building Block for Hole-Transporting Materials: Toward Efficient and Stable Perovskite Solar Cells.

The construction of state-of-the-art hole-transporting materials (HTMs) is challenging regarding the appropriate molecular configuration for simultaneously achieving high morphology uniformity and charge mobility, especially because of the lack of appropriate building blocks. Herein a semi-locked tetrathienylethene (TTE) serves as a promising building block for HTMs by fine-tuning molecular planarity. Upon incorporation of four triphenylamine groups, the resulting TTE represents the first hybrid orthogonal and planar conformation, thus leading to the desirable electronic and morphological properties in perovskite solar cells (PSCs).

Low cost and stable quinoxaline-based hole-transporting materials with a D-A-D molecular configuration for efficient perovskite solar cells.

The use of expensive hole transporting materials (HTMs), such as spiro-OMeTAD, in perovskite solar cells (PSCs) is one of the critical bottlenecks to hinder their large-scale applications. Some low-cost alternatives have been developed by combining conjugated electron-rich cores with arylamine end-caps, usually in a donor-π spacer-donor (D-π-D) molecular configuration. However, incorporation of electron-rich cores can lead to undesirable up-shift in the HOMO energy level and low stability, and few of these new HTMs can outperform spiro-OMeTAD in terms of device efficiency.

Molecular Engineering of Quinoxaline-Based D-A-π-A Organic Sensitizers: Taking the Merits of a Large and Rigid Auxiliary Acceptor.

The continuing efforts of creating novel D-A-π-A structured organic sensitizers with excellent optoelectronic properties have resulted in substantial improvement of power conversion efficiency (PCE) as well as stability of dye-sensitized solar cells (DSSCs). Here, we report a new molecular engineering strategy for enhancing optical gain and improving excited-state features in D-A-π-A structured organic sensitizers by improving the conjugation size and rigidity of the auxiliary acceptor functional group. A series of phenanthrene-fused-quinoxaline (PFQ)-based D-A-π-A organic sensitizers (WS-82, WS-83, and WS-84) are designed and synthesized for applications in DSSCs.

Molecular engineering and sequential cosensitization for preventing the "trade-off" effect with photovoltaic enhancement.

In dye-sensitized solar cells (DSSCs), it is essential to use rational molecular design to obtain promising photosensitizers with well-matched energy levels and narrow optical band gaps. However, the "trade-off" effect between the photocurrent and photovoltage is still a challenge. Here we report four benzoxidazole based D-A-π-A metal-free organic dyes (, , and ) with different combinations of π-spacer units and anchoring-acceptor groups.