The cause was prostate cancer, his son Harvey said.

Placing Mr. Ovshinsky in "the league of genius inventors," The Economist magazine once titled an article about him "The Edison of Our Age?"

If not quite that, he was certainly among the 20th century's most inventive breed of scientists who, like Edison, parlayed their ideas into practical commercial applications.

He gained particular attention for upsetting common wisdom about the nature of semiconductors. Semiconductors, which block or carry electrical current depending on the voltage to which they are exposed, typically consist of crystals in which molecules line up in ordered ranks. But in the late 1950s Mr. Ovshinsky became convinced that less regimented materials could also act as semiconductors.

He argued that products using these so-called amorphous, or disordered, materials could be much cheaper to make than those built from the workhorse compounds of the electronics industry, like silicon crystals.

His ideas drew only scorn and skepticism at first. He was an unknown inventor with unconventional ideas, a man without a college education who made his living designing automation equipment for the automobile industry in Detroit, far from the hotbeds of electronics research like Silicon Valley and Boston.

But Mr. Ovshinsky prevailed. Industry eventually credited him for the principle that small quantities or thin films of amorphous materials exposed to a charge can instantly reorganize their structures into semicrystalline forms capable of carrying significant current.

With a bit of a promotional twist, he christened the field "ovonics."

In 1960, he and his second wife, the former Iris L. Miroy, founded Energy Conversion Laboratories in Rochester Hills, Mich., to develop practical products from the discovery. It was renamed Energy Conversion Devices four years later.

Energy Conversion Devices and its subsidiaries, spinoff companies and licensees began translating Mr. Ovshinsky's insights into mechanical, electronic and energy devices, among them solar-powered calculators. His nickel-metal battery is used to power hybrid cars and portable electronics, among other things.

He holds patents relating to rewritable optical discs, flat-panel displays and electronic-memory technology. His thin-film solar cells are produced in sheets "by the mile," as he once put it.

The Ovshinskys were champions of alternative energy and sounded early alarms about the industrial world's insatiable demand for oil, saying it could lead to resource wars and climate change. More than 50 years ago, Mr. Ovshinsky began promoting hydrogen fuel cells as an alternative to the internal-combustion engine.

In his so-called hydrogen loop, water is converted to stored hydrogen through solar-powered electrolysis, and from hydrogen back to water, generating electricity through a fuel cell. Automotive companies have begun producing hydrogen-based demonstration models.

Mr. Ovshinsky's promotional flair helped Energy Conversion Devices attract investors, including giants like Standard Oil, Texaco, Chevron, Canon, 3M, Intel and General Motors. They collectively invested hundreds of millions of dollars in his ventures, some of which failed.

Mr. Ovshinsky's business maneuvers came to be considered every bit as creative and extraordinary as his inventions. Energy Conversion Devices lost money decade after decade, surviving by periodically selling control of patents, rights to royalties from them or new stock.

In 1989, when the company was completing the 29th of what would become a string of 35 years of losses, Forbes described it as "a high-tech Roach Motel" where "the money goes in but it never comes out."

Mr. Ovshinsky recruited Robert Stempel, a former chairman and chief executive of G.M., to help run the company in 1993. Mr. Stempel became chairman in 1995 and retired in 2007. (He died in 2011.)

The practical applications of his ideas never fully diverted Mr. Ovshinsky from his passion for basic materials research. He continued to help write scientific papers and cultivated relationships with luminaries like Nevill F. Mott, who won the 1977 Nobel Prize in Physics for explaining the underlying behavior of amorphous materials.

"His incredible curiosity and unbelievable ability to learn sets him apart," Hellmut T. Fritzsche, a longtime friend and consultant, said in an interview in 2005.

Mr. Fritzsche was a noted semiconductor researcher at the University of Chicago when Mr. Ovshinsky called him in 1963 to ask him to visit Energy Conversion Devices.