Perovskite solar cells (PSCs) have excelled in achieving high open circuit voltages (Voc) with narrow band gaps (∼1.6 eV), but face challenges with wide band gap perovskites such as methylammonium lead trichloride (MAPbCl ) has a band gap of 3.03 eV. These materials are transparent when visible light absorbs ultraviolet (UV) light. However, achieving uniform thin film crystallization remains an obstacle.
Here, Mahdi Malekshahi Byranvand and Michael Saliba of the University of Stuttgart enhanced the crystallization of MAPbCl 3 by manipulating the annealing atmosphere (nitrogen, air and MACl vapor). Excess MACl vapor increases surface coverage, which is critical for film stability. The article demonstrates that the microstructure of perovskite films, including surface morphology, grain boundaries and interfaces, can affect photovoltaic performance.
The subsequently obtained Voc of 1.78 V is the highest record for single-junction PSCs, and the traditional hole transport layer Spiro-OMeTAD optimized for the narrow band gap is able to maintain such a high voltage. Photoluminescence measurements revealed a trap-assisted recombination peak at 1.65 eV, indicating that deep traps in MAPbCl 3 are important for voltage loss.
Waqas Zia, Mahdi Malekshahi Byranvand, et al. MAPbCl3 Light Absorber for Highest Voltage Perovskite Solar Cells. ACS Energy Letters 0, 9
DOI: 10.1021/acsenergylett.3c02777