Emerging photovoltaic (PV) technologies are being developed to improve the performance and the stability of solar cells. This thesis focused on the development of scalable and stable solar cells by assembling heterojunction devices. These devices combined perovskites (PK) with quantum dots (QDs) or bismuth-based nanocrystals (NCs). First, single junction solar cells with PK as active layers were fabricated and characterized under ambient conditions (no glove box) to offer a low cost and stable solution with high potential for large scale production. Two types of PV devices (spin coated and drop casted) were prepared using two modified MAPbI3 perovskite formulations (MAPbIxCl1-x and MA1-x(AVA)xPbI3) across planar (C-PSC) and mesoporous (M-PSC) configurations. The resulting maximum power conversion efficiencies (PCE) of the devices were 10.7% and 12.9% for drop casted and spin coated cells, respectively. Afterwards, the research continued with the synthesis and characterization of Bi2S3 NCs and their introduction into PV devices in combination with perovskite. However, the results were not the optimal, as the performance was not improved. On a different approach, CsPbBr3 QDs were synthesized by ligand-assisted room temperature processing and compared with commercial QDs produced with the traditional hot-injection method. The two materials had similar optical properties, but differed in their morphology and chemical environment. Different PV devices were fabricated via drop casting using various integration strategies, mixing QDs within the PK (MA1-x(AVA)xPbI3) layer, bilayer heterojunction or applying them on the outer glass surface. The performance obtained by coupling QDs (Q-PSC) with PK was better than PK alone (PSC), from 9.3% for control samples to 10.4% for samples with QDs, with an absolute PCE increase of 11.8%. Dedicated characterizations techniques were used for the analysis of layer modifications due to degradation. To further investigate the stability of these heterojunction devices, aging campaigns at damp heating (85°C/85% RH) conditions and light soaking (1 SUN) exposure were conducted. The study provided in-depth insights into degradation pathways and explored how QDs influence stability and long-term performance.

Programa de Doctorado en Ingeniería Química y del Medio Ambiente de la Universidad de Zaragoza.

Peer reviewed