Energy Level Tuning in CsPbBr3 Perovskite Solar Cells through In Situ-Polymerized PEDOT Hole Transport Layer.

The all-inorganic CsPbBr3 perovskite solar cells exhibit excellent stability against humidity and thermal conditions as well as relatively low production cost, rendering them a gradually emerging research hot spot in the field of photovoltaics. However, the absence of a hole transport layer (HTL) in its common structure and the substantial energy level difference of up to 0.6 eV between the highest occupied molecular orbital (HOMO) level of CsPbBr3 and the work function of the carbon electrode have emerged as the primary factor limiting the improvement of its power conversion efficiency (PCE). In this work, the monomer 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) is spin-coated onto the surface of the CsPbBr3 film directly and then subjected to annealing; DBEDOT undergoes in situ polymerization to form poly(3,4-ethylenedioxythiophene) (PEDOT), which aims to ameliorate the issue of excessive energy level difference between CsPbBr3 and the carbon electrode, and to facilitate the extraction and transport efficiency of holes between the CsPbBr3 perovskite and the carbon electrode. Compared to the pristine device, the PCE of the device based on in situ polymerization is enhanced and achieves a maximum efficiency of 9.81%. Furthermore, the unencapsulated devices based on in situ polymerization maintain 95.9% of their original efficiency after 40 days of stability testing.

Hierarchical Ni(OH)2/Cu(OH)2 interwoven nanosheets in situ grown on Ni-Cu-P alloy plated cotton fabric for flexible high-performance energy storage.

Flexible energy storage electrodes with high conductivity and capacity are crucial for wearable electronic clothes. Herein, a flexible hierarchical Ni(OH)2/Cu(OH)2 interwoven nanosheets in situ coated on Ni-Cu-P alloy plated cotton fabric textile (NCO/CF), which displays perfect conductive and electrochemical performance, is prepared by electroless deposition and electrochemical oxidation method. While the Ni-Cu-P alloy layer coated on the fabric effectively contributes to excellent mechanical performance and electro-conductivity of the as-prepared NCO/CF electrode, the hierarchical Ni(OH)2/Cu(OH)2 interwoven nanosheets in the oxidation layer effectively lead to a high energy storage performance with a specific areal capacity of 4.7 C cm-2 at a current density of 2 mA cm-2. When the power density of the two-electrode system based on NCO/CF and the carbon cloth (CC) is 2.4 mW cm-2, the energy density is 1.38 mW h cm-2. Furthermore, the flexible solid-state energy storage f-NCO/CF//CC is assembled in a self-powered system and supplies continuous power for electronic devices, demonstrating that NCO/CF is promising to be applied in various energy storage devices to power portable and wearable devices in the future.