Design and synthesis of small molecules for photo voltaics

Abstract

Introduction The current energetic regime, which relies on non-renewable polluting energy sources, is unsustainable from societal, economical, geopolitical, and environmental points of view. The only fully renewable source able to meet world’s huge and always growing energy demand is solar energy. Photovoltaic technologies, directly converting sunlight into electricity, represent one of the most promising candidates to meet this demand. Objectives Chapter 1: Development of new small molecules for organic solar cells (OSC). Chapter 2: Development of new small molecules as hole transporting materials (HTM) for perovskite solar cells. Results and Discussion Chapter 1. Small molecules for organic solar cells i) A−D−A Small molecules based on BDT-BTD Electroactive molecules featuring A−D−A architecture that employ some of the best performing electron donor and acceptor fragments found in the literature, namely benzodithiophene (BDT, as donor) and benzothiadiazole (BTD, as acceptor) have been designed and synthesized. Thiophene bridges of increasing length have been inserted in between A and D moieties (Figure S1a) in order to improve the absorption and aggregation properties. Optical, electrochemical and computational studies have revealed their electroactive nature and their ability to form well-ordered crystalline thin films. Photovoltaic devices employing these materials as donors in blends with fullerene derivatives showed poor performances, with best performing material (31) providing 0.72% PCE (Figure S1b)...