A new kind of solar cell - made by drying a special liquid on a surface - is being heralded as a revolution in solar power. The minerals known as perovskites were discovered more than 150 years ago. More recently, their crystal structure has been copied using other materials and used to produce energy. If it can be made to work, these crystals could be used to literally print out solar cells to put on skyscraper walls, furniture and electrical gadgets. Produced and presented by Tom Colls Image: Olga from Saule Technology