historical Background

Early research into thin-film solar cells began in the 1970s. In 1970, Zhores Alferov's team at Ioffe Institute created the first gallium arsenide (GaAs) solar cells, later winning the 2000 Nobel prize in Physics for this and other work.Two years later in 1972, Prof. Karl B?er founded the Institute of Energy Conversion (IEC) at the University of Delaware to further thin-film solar research. The institute first focused on copper sulfide/cadmium sulfide (Cu2S/CdS) cells and later expanded to zinc phosphide (Zn3P2) and amorphous silicon (a-Si) thin-films as well in 1975. In 1973, the IEC debuted a solar-powered house, Solar One, in the first example of residential building-integrated photovoltaics. In the next decade, interest in thin-film technology for commercial use and aerospace[8] applications increased significantly, with several companies beginning development of amorphous silicon thin-film solar devices.Thin-film solar efficiencies rose to 10% for Cu2S/CdS in 1980, and in 1986 ARCO Solar launched the first commercially-available thin-film solar cell, the G-4000, made from amorphous silicon.In the 1990s and 2000s, thin-film solar cells saw significant increases in maximum efficiencies and expansion of existing thin-film technologies into new sectors. In 1992, a thin-film solar cell with greater than 15% efficiency was developed at University of South Florida.[12] Only seven years later in 1999, the U.S. National Renewable Energy Laboratory (NREL) and Spectrolab collaborated on a three-junction gallium arsenide solar cell that reached 32% efficiency. That same year, Kiss + Cathcart designed transparent thin-film solar cells for some of the windows in 4 Times Square, generating enough electricity to power 5-7 houses. In 2000, BP Solar introduced two new commercial solar cells based on thin-film technology. In 2001, the first organic thin-film solar cells were developed at the Johannes Kepler University of Linz. In 2005, GaAs solar cells got even thinner with the first free-standing (no substrate) cells introduced by researchers at Radboud University.This was also a time of significant advances in the exploration of new third-generation solar materials–materials with the potential to overcome theoretical efficiency limits for traditional solid-state materials. In 1991, the first high-efficiency dye-sensitized solar cell was developed, replacing the ordinary solid semiconducting (active) layer of the cell with a liquid electrolyte mixture containing light-absorbing dye. In the early 2000s, development of quantum dot solar cells began,technology later certified by NREL in 2011. In 2009, researchers at the University of Tokyo reported a new type solar cell using perovskites as the active layer and achieving over 3% efficiency,[19] building on Murase Chikao's 1999 work which created a perovskite layer capable of absorbing light.

In the 2010s and early 2020s, innovation in thin-film solar technology has included efforts to expand third-generation solar technology to new applications and to decrease production costs, as well as significant efficiency improvements for both second and third generation materials. In 2015, Kyung-In Synthetic released the first inkjet solar cells, flexible solar cells made with industrial printers. In 2016, Vladimir Bulovi?'s Organic and Nanostructured Electronics (ONE) Lab at the Massachusetts Institute of Technology (MIT) created thin-film cells light enough to sit on top of soap bubbles.In 2022, the same group introduced flexible organic thin-film solar cells integrated into fabric.Thin-film solar technology captured a peak global market share of 32% of the new photovoltaic deployment in 1988 before declining for several decades and reaching another, smaller peak of 17% again in 2009.Market share then steadily declined to 5% in 2021 globally, however thin-film technology captured approximately 19% of the total U.S. market share in the same year, including 30% of utility-scale production